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Poisoning the Well
D. N. WALTON
Department of Philosophy
University of Winnipeg
515 Portage Avenue
R3B 2E9, Winnipeg, MB
ABSTRACT: In this paper it is shown is that although poisoning the well has generally
been treated as a species of ad hominem fallacy, when you try to analyze the fallacy using
ad hominem schemes, even by supplementing with related schemes like argument from
position to know, the analysis ultimately fails. The main argument of the paper is taken
up with proving this negative claim by applying these schemes to examples of arguments
associated with the fallacy of poisoning the well. Although there is a positive ﬁnding in
this quest, in that poisoning the well is shown to be based on and associated with these
forms of argument in interesting ways, the paper in the end is led to the conclusion that
the fallacy is irreducibly dialectical. Poisoning the well is thus analyzed as a tactic to
silence an opponent violating her right to put forward arguments on an issue both parties
have agreed to discuss at the confrontation stage of a critical discussion. It is concluded
that it is a special form of strategic attack used by one party in the argumentation stage of
a critical discussion to improperly shut down the capability of the other party for putting
forward arguments of the kind needed to properly move the discussion forward.
KEY WORDS: ad hominem, argumentation schemes, bias, commitment, fallacy,
personal attack, position to know argument, silencing an opponent, strategic
Poisoning the well has become familiar in logic textbooks, where it has
often come to be treated as a species of ad hominem fallacy. It is also
closely related to other common forms of argument like argument
from bias, arguments alleging group bias, argument from position to
know, and special subtypes of ad hominem argument like the bias type
and the situationally disqualifying type (Walton, 1998). The problem
confronted in this investigation is whether the fallacy of poisoning the
well can be analyzed by identifying it as a distinctive type of argumen-
tation represented by one of these argumentation schemes, and show-
ing how the scheme was wrongly used in a set of fallacious cases. This
sort of problem arises with many fallacies, because even though the
fallacy relates to a particular argumentation scheme, there turn out to
be several ways the scheme can be misused or exploited, as shown by
examples. It is shown in this paper that even once a serious series of
attempts have been made to analyze the fallacy of poisoning the well
Argumentation (2006) 20:273–307 ÓSpringer 2006
using ad hominem schemes and related schemes like argument from
position to know, each analysis ultimately fails. This negative hypothe-
sis is proved by applying the schemes to examples of arguments that
commit the fallacy of poisoning the well. But there is a positive ﬁnding
in this quest, in that poisoning the well is shown deﬁnitely to be based
on and associated with these forms of argument in interesting ways.
Following through this procedure of analysis leads to some surpris-
ing and controversial results. One conclusion arrived at is that poison-
ing the well is a distinctive pattern of argumentation in its own right,
one that can exist separately from the argumentum ad hominem in
some instances. Another is that poisoning the well in some cases is
based on a kind of argumentation that has an inherent plausibility and
that, to some degree, represents a kind of rational argumentation.
Based on analyses of examples, the study reveals how poisoning the
well works as a fallacy, one that is both subtle and dangerous. Like all
fallacies, it is based on some superﬁcial plausibility enhanced by argu-
mentation that is not only persuasive to an audience and has a
rational core, yet is exploited, misdirected, or blown out of proportion
in a cleverly misleading way, making it useful as a powerful tactic
of deception. It is concluded that this fallacy can only be explained
adequately by seeing how it functions as a tactic to suppress the
capacity to rationally persuade and to be persuaded (Johnstone, 1981).
Evaluation of a case is achieved by identifying the argumentation
scheme and seeing how it violates normative requirements of a critical
discussion agreed to at the prior confrontation stage (van Eemeren
and Grootendorst, 1984, 1992, 2004). On this analysis, poisoning the
well is explained as a dialectical tactic used to silence an opponent by
a blocking technique deployed improperly at the argumentation stage.
1. POISONING THE WELL
Argumentum ad hominem is taken both in logic and common speech to
refer to a case in which one party has put forward an argument and
her opponent uses personal attack instead of trying to refute or
address her argument based on the evidence for or against it.
Personal attack may be taken to refer to an attack on the arguer’s
character, particularly his ethical character (ethos). In its other forms,
ad hominem can also be based on an arguer’s personal circumstances,
arguing he does not practice what he preaches, or it can be an attack
that alleges that an arguer is biased, and that his argument is based on
self-interest. Recent research (Johnstone, 1959, 1978, 1981; Walton,
1998) has shown that ad hominem arguments are by no means always
fallacious. Johnstone (1978, p. 134) even argued that argumentum ad
hominem is ‘‘the only valid argument in philosophy’’, deﬁning it as ‘‘
274 D. N. WALTON
the criticism of a position in terms of its own presuppositions.’’ To
cite another kind of example of reasonable use of ad hominem,
attacking the character of a witness can be admitted in court in many
instances. It is often judged to be a reasonable way of trying to assess
the worth of witness testimony through cross-examination of the
witness in the trial. Even so, personal attack is extremely dangerous
as a form of argument. It can be irrelevant, and it can prejudice an
audience. It can be based on innuendo rather than real evidence,
and can have a powerful smear eﬀect in persuasion much out of
proportion to the real worth of the argument.
The classic case of poisoning the well is the Cardinal Newman
Argument. Copi and Cohen (1998, p. 169) deﬁned it under the general
category of ad hominem arguments using this historical example that
has become a paradigm of the fallacy.
1.1. The Cardinal Newman argument
One argument of this kind, called ‘‘poisoning the well,’’ is particularly perverse. The
incident that gave rise to the name illustrates the argument forcefully. The British
novelist and clergyman Charles Kingsley, attacking the famous Catholic intellectual
John Henry Cardinal Newman, argued thus: Cardinal Newman’s claims were not
be trusted because, as a Roman Catholic Priest, (Kingsley alleged) Newman’s first
loyalty was not to the truth. Newman countered that this ad hominem attack made
it impossible for him and indeed for all Catholics to advance their arguments, since
anything that they might say to defend themselves would then be undermined by
others’ alleging that, after all, truth was not their ﬁrst concern. Kingsley, said Cardi-
nal Newman, had poisoned the well of discourse.
Newman was so upset by Kingsley’s attack that he wrote a whole
book, Apologia Pro Vita Sua (1864), directed to refuting what he felt
was the argument against him.
He felt that Kingsley’s argument
unfair, because it was based on a misinterpretation of what he (New-
man) had written. But even worse, he felt that Kingsley’s argument
threw such an aura of suspicion on anything he might write, or any
argument he might put forward in the future that the well would be
poisoned. Any such argument would always be tainted with the sus-
picion that Newman’s views were based on putting group interest
before a concern for the truth. Not only would such an attack make
it impossible for Newman to have a say on any intellectual or politi-
cal issues. It would make it impossible for any Catholic to do
so with any credibility. Newman was right to be upset, and to
take great care to reply to Kingsley’s attack, because this type of
poisoning the well argument can be extremely powerful as an
unfair method of attacking an opponent. The attack could be highly
eﬀective even if it was only an implicit argument against Newman,
POISONING THE WELL 275
or anything he has written, by claiming that Roman Catholics
generally have no regard for truth.
One can easily see why poisoning the well is categorized under the
ad hominem fallacy in the textbook accounts. The ad hominem
argument is an attack on the person that throws an arguer’s credibility
into doubt or disrepute, thus undermining the worth of her argument.
Poisoning the well is the same kind of attack because it attacks the
trustworthiness and the intellectual honesty of the arguer as a credible
source, undermining her sincerity or objectivity in a way that makes
an audience discount the worth of her arguments. Attacking an arguer
as biased is also often classiﬁed under the ad hominem category in the
textbook accounts of fallacies. Since poisoning the well appears to be
a form of bias attack, it too naturally seems to ﬁt in the ad hominem
category. It is well to be warned, however, that there is much variation
in these accounts.
In the current textbooks, we ﬁnd examples (Moore and Parker,
2001, p. 176) that are comparable to the Cardinal Newman argument,
and are placed in the category of the ad hominem fallacy, but not
under the poisoning the well classiﬁcation.
John says that we should reject what Father Hennesy says about the dangers of
abortion because, ‘‘After all, he’s a Catholic priest, and priests are required to hold
This argument appears quite similar to the Cardinal Newman argu-
ment. However, it’s less evident that Father Hennesy is being
attacked personally. It is not explicitly claimed that he is intellectu-
ally dishonest, or has no regard for the truth. It does say that as a
Catholic priest, he is required to hold an anti-abortion view.
It’s not explicitly claiming he is biased, but it is saying that as a
member of a group, he is required to hold a particular viewpoint
on the issue being discussed. The poisoning the well type of argu-
ment can be very dangerous. It can shut down a discussion by
disqualifying one arguer from putting forward any argument, no
matter how good it is, or how much it based on good evidence,
simply because any argument he puts forward will always be seen
as simply reﬂecting this same bias. His (or her) arguments will
always be seen as biased and one-sided, and therefore limited and
unconvincing. If disqualiﬁed as arguments that only promote
or advocate an interest, pushing ahead covertly for gains for an
interest group, they can be discounted, even though they may have
merit, and be worth considering.
The following example of the poisoning the well fallacy from the
House of Commons Debates of Canada (Volume 2, November 30, 1979,
p. 1920) was cited in (Walton, 1987, p. 217). In the middle of a
276 D. N. WALTON
lengthy debate on the abortion issue, one of the participants made the
1.2. The abortion argument
I wish it were possible for men to get really emotionally involved in this question. It
is really impossible for the man, for whom it is impossible to be in this situation, to
really see it from the woman’s point of view. That is why I am concerned that there
are not more women in this House available to speak about this from the woman’s
point of view.
According to the comment on this argument made in (Walton, 1987,
p. 217) the speaker is arguing that a man can’t help being opposed to
abortion, or at least adopting a particular viewpoint on the subject,
simply because he is male. Since he is not a female, the argument
implies, the topic is inaccessible to his full understanding. He is not in
a position to know about it, and therefore anything he might say must
be discounted in advance as representing a limited and biased point of
A problem with this kind of argument is that it can easily be turned
on its head, and this move can result in a stalemate that effectively
stops further meaningful discussion of an issue. For example, as noted
in (Walton, 1998, p. 231), a comparable argument can be made: ‘‘You
can never believe or take seriously anything she says on the abortion
issue because, as a woman, she will always take the feminist point of
view, which supports her own interests as a female’’. Layman (2000,
p. 167) classiﬁed the following example as an ad hominem argument on
the ground that ‘‘an attempt is made to discredit the argument by
showing that the arguer has something to gain.’’ (p. 167).
Ms. Fitch argues in favor of equal pay for equal work. She says it doesn’t make
sense to pay a person more for doing the same job just because he is male or Cau-
casian. But since Ms. Fitch is a woman, it’s to her personal advantage to favor
equal pay for equal work. After all, she would get an immediate raise if her boss
accepted her argument. Therefore, her argument is worthless.
In this example, the argument is used against the woman, discount-
ing the worth of her argument on the ground that she has something
to gain by adopting the point of view supporting equal pay for equal
work. In this example, the argument falls into the bias category, and
like the abortion example above, it also falls into the category of poi-
soning the well.
There are many problems with trying to better understand how
such arguments work, and to see how they should be identiﬁed, ana-
lyzed and evaluated. Pointing out that an arguer is biased can be a
POISONING THE WELL 277
legitimate move in argumentation. For example, in law, arguing that a
witness is biased is regarded as a relevant argument in a trial. But
such arguments can easily deteriorate into fallacies, the most evident
being the argumentum ad hominem. Indeed, poisoning the well is stan-
dardly taken in the logic textbooks, as indicated above, as species of
ad hominem fallacy. However, some textbooks characterize the poison-
ing the well type of argument in quite a broad way as a method of
forestalling disagreement. On this approach the poisoning the well
argument does not have to be a subspecies of argumentum ad homi-
nem. The following example was presented as a fallacy by Davis (1986,
p. 62), but as one not coming under the ad hominem heading.
For example, in a debate on how to put the Social Security system on a sound
financial basis, a congressman might say, ‘‘It would be indecent to even suggest that
Social Security payments should be cut.’’ Note that all the congressman has really
said is that Social Security payments should not be cut; he has not given so much
as a suggestion as to why. Nevertheless, he has made it very difficult to disagree.
Anyone doing so faces the charge of being ‘‘indecent,’’ which might be embarrass-
ing. Forestalling disagreement by positive characterizing those who would agree
with speaker’s position or negatively characterizing those who would disagree is
called ‘‘poisoning the well’’.
My own approach to this kind of example would be not to treat it
as an ad hominem argument at all, but as a case of argument from a
verbal classiﬁcation. The problem is one of the argumentative deploy-
ment of loaded terms to make a claim without, as Davis says, giving
evidence to show why the claim is true.
The cases presented above show that there are serious doubts about
how to understand the poisoning the well argument. To begin with,
there is one pressing question that needs to be answered before any
progress can be made on analyzing this type of argument. Does it
belong in the ad hominem category or not? The place to begin is by
trying to reach some agreement on how the argumentum ad hominem
should be clearly deﬁned as a class of arguments, on what its main
subtypes are, especially as related to poioning the well, and on how
these are to be deﬁned. There is some broad agreement on a starting
point. We can take the argumentum ad hominem to be deﬁned in out-
line by the following framework. An argument is an argumentum ad
hominem if, and only if, (a) two parties are having a dialogue, (b) one
has put forward an argument that he advocates, (c) the other attacks
his argument by claiming that he lacks credibility and that his argu-
ment should therefore be discounted, or valued as less strong than it
seemed. The attack can be based on several grounds. One is an allega-
tion that the arguer has a character that is ethically bad in some
respect, for example that he is a liar. Another is that his personal
278 D. N. WALTON
circumstances are in conﬂict with his argument. Another is that he is
biased – for example, it might be argued that he has something to gain
by taking the view he does. The poisoning the well examples cited
seem initially to ﬁt into this framework as ad hominem arguments, at
least for the most part, even if in diﬀerent ways. But much depends on
how widely or narrowly argumentum ad hominem is deﬁned. If an ad
hominem argument has to be a personal attack, and based on an
attack on an arguer’s character, not all these examples might ﬁt,
if they can be construed as making allegations about the group
membership of an arguer, as opposed to his good or bad character.
There is another factor about poisoning the well arguments that
makes them very dangerous and very powerful in inﬂuencing an audi-
ence. This factor is illustrated by an actual case cited by Damer (1980,
1.3. The black alienation argument
Several years ago, at a public symposium on alienation held at Emory & Henry Col-
lege, Howard Fuller, a black militant, refused to listen to the integrationist-oriented
remarks of well-known philosopher Sidney Hook. Fuller said: ‘‘You’re not a black
man, so anything you have to say on the subject of black alienation is of no interest
to me. You just can’t know what you’re talking about.’’ Professor Hook’s well had
been effectively poisoned. Anything that he had to say was regarded as tainted in
Fuller’s mind, and after Fuller’s attack, anything that Hook had to say was regarded
as tainted in the thinking of many members of the symposium audience.
This argument is similar to the abortion argument in a certain respect.
The principle behind both is that if you don’t belong to a certain group
then you can’t speak in a way that is worth listening to about some
issue that deeply affects that group. Since you cannot personally be in a
position to know about the issue as it affects that group, you lack the
personal insight to share their viewpoint, to deeply understand it in a
way that would enable you take part in a balanced discussion of it.
One can see why Damer thinks this argument is fallacious. Perhaps
Sidney Hook had some things to say about the issue of integration,
but as Damer noted, this argument against him poisoned the well by
discounting anything he did say, as well as anything he might have
said, even in advance of his saying it. It seems to be a very dangerous
one because it is so emotionally powerful and because it has such a
silencing effect, closing off a dialogue. However, like all powerfully
persuasive arguments of this kind, the argument is not completely
worthless. Like the abortion argument, it is based on a true premise to
the effect that the arguer does not belong to a certain group, and cor-
rectly draws the conclusion that he or she cannot personally experi-
ence certain feelings that members of the group experience, as
POISONING THE WELL 279
members of the group. Thus a man is not a member of the group of
women, and thus he cannot experience certain feelings about abortion
of the kind that can only be experienced by women.
The argument does have a parallel in the argumentum ad verecundi-
am in which the layperson on an issue is told, ‘‘You’re not an expert.
What do you know about it?’’ and then this argument is used to dis-
count anything he says. This is a powerful argument, and a hard one
to react to and overcome, especially for those of us who are diﬃdent
about challenging experts, and are aﬀected by the so-called ‘‘halo
eﬀect’’. However the parallel is not exact. In the poisoning the well
argument, the person is being silenced not because she lacks expertise
or scientiﬁc knowledge on an issue, but because she lacks personal
experience of a kind that only members of a certain group can directly
feel. Poisoning the well is so dangerous because it has the eﬀect of
shutting down rational discussion on an issue. An arguer is portrayed
as not being in a position to speak on the issue, or even as having no
regard for the truth of the matter of being discussed. Such an arguer is
seen as not being capable of rational argumentation. Once a party to a
rational discussion sees the other as incapable of grasping the opposed
viewpoint, or as merely promoting group interests in a closed-minded
way, attempting to carry on with rational argumentation of a kind
aimed at ﬁnding the truth of the matter being discussed appears futile.
Because of its powerful eﬀect as a device for shutting down rational
discussion of an issue, poisoning the well is worthy of study in the
domain of fallacies.
2. THE SITUATIONALLY DISQUALIFYING TYPE OF AD HOMINEM
There is another type of ad hominem that has been recognized that is
especially interesting in relation to poisoning the well, because it
appears to be based on a similar principle, even if it does not quite seem
to ﬁt in the exactly the same category. It also has to do with being
personally in a kind of situation that entitles one to talk meaningfully
about an issue. The best place to begin to identify this type of argument
is with the classic case presented in (Krabbe and Walton, 1993, p. 79).
2.1. The Gulf war argument
(Holland December, 1990) A retired Major General argues in front of his relatives
that the Dutch government must give more substantial support for the Allied efforts
in the Gulf Area. ‘‘We ought to send ground forces,’’ so he claims. His grandson
retorts: ‘‘Its all very well for you to talk, Grandpa! You don’t have to go there.’’
280 D. N. WALTON
The supposed facts of the case are that the grandfather is retired
and there is therefore no chance that he will be sent out to partici-
pate in the Gulf War. According to the grandson’s argument the
grandfather is disqualiﬁed as a serious advocate of a credible argu-
ment contending that we ought to send ground forces the Gulf.
Since he is too old to serve in the military, and will not suffer for
the consequences of this action, he is not entitled to put the argu-
ment forward with any credibility. Krabbe and Walton described this
argument as a type of personal attack they called a situationally dis-
qualifying ad hominem argument. According to the Krabbe and Wal-
ton analysis, the idea behind the situationally disqualifying type of
ad hominem argument is that in certain situations a person can be
viewed as not being in a position to express a particular viewpoint
or argue for it in a certain way. The idea is that they are not enti-
tled to do so because of something about their personal situation.
Krabbe and Walton argued that this situational type of argument is
a species of ad hominem argument in its own right, distinct from the
direct type, the circumstantial type and the bias type. The circum-
stantial type is deﬁned as applying to a narrower range of cases
where there is some clash of propositions, that is, an inconsistency,
representing the type of case where the person does not practice
what he preaches. According to Krabbe and Walton, the situation-
ally disqualifying type of ad hominem argument is more like the poi-
soning well type in that it is used to prematurely close oﬀ a
dialogue. In (Walton and Krabbe, 1995, p. 86) the following deﬁni-
tion of the situationally disqualifying ad hominem type of argument
is given: ‘‘The situationally disqualifying ad hominem attack (or situa-
tional ad hominem) is an argumentative move in dialogue whereby
one participant points out certain features in his adversary’s personal
situation that are claimed to make it inappropriate for this adversary to
make a certain dialectical contribution’’. Such features may include
lack of concern for, or lack of insight into the issue under discussion,
excluding evidence for a positional inconsistency or a bias.
There is another type of argument commonly used that is compara-
ble to the argument used in the Gulf War example above. An example
would be the kind of case in which a politician lays out a farm policy
for the federal government, and a farmer replies, ‘‘What does he know
about it? He’s never farmed in his life.’’ This type of argument can be
quite effective because it seems to disqualify the politician as a speaker
who can say anything that ought to be taken seriously on the subject
of farming. Certainly other farmers would tend to be sympathetic to
this type of argument.
An actual example of this type of argument can be found on a mes-
sage board on the web site military.com. In this case, William S. Lind
POISONING THE WELL 281
had written an article on the decision to purchase LAV’s (light
armored vehicles) by the US Army. Paul G. Davitt put forward a
criticism of Lind’s article containing the following argument.
2.2. The armored vehicles argument
Just read his piece on LAVs in Iraq and while I don’t know if he’s right or wrong
(I’m no Armor guy, just a retired MI guy) I wonder why we care what he thinks on
topics of this nature? Reading his bio I saw nothing about him serving in the mili-
tary. Yes, he’s a smart guy, and has some alphabet soup after his name these days,
but really, what does he know about the proper uses of LAVs? I don’t see where he
ever served as a tank/track commander or served period. Why are we wasting time
listening to someone who doesn’t seem to have been there and done that? He wrote
a book on Maneuver Warfare? Where did he learn how to maneuver?
According to this argument, we are ‘‘wasting our time’’ listening to
Lind’s argument because Lind has not served in the armed forces, and
therefore presumably has no experience of driving armored vehicles.
Hence, it is argued, we can dismiss his views on the subject, and his
argument about LAV’s is refuted.
The armored vehicles argument appears to be very similar to the
Gulf War argument. Both seem to be situationally disqualifying argu-
ments in the sense of Krabbe and Walton (1993). This type of argu-
ment has the following structure.
2.3. Argumentation scheme for the situationally disqualifying argument
In dialogue D,aadvocates argument a, which has proposition Aas its
ahas certain features in his personal situation that make it inappropri-
ate for him to make a dialectical contribution to D.
Therefore, a’s argument ashould not be accepted.
Both arguments share this scheme, but there is a difference. The ar-
mored vehicles argument dismisses the argument it was designed to re-
fute on the grounds that the arguer is not in a position to know about
using armored vehicles in the military. The reason presumably is that
he has never had direct experience with actually using such vehicles or
directing their use in military operations. Part of the reason for the
power of this argument is that it suggests that the arguer lacks the
kind of practical expertise or hands-on experience to offer an authori-
tative opinion on the subject under discussion. Since he is not in a po-
sition to know about such things, his argument, or any argument he
offers on the subject, can be dismissed out of hand. Thus the armored
vehicles arguments is a position to know type of argumentation,
whereas the Gulf War argument did not rest in the same way on dis-
282 D. N. WALTON
qualifying the arguer because he was not in a position to know. In-
deed, the grandfather did serve in the military, and was even a general.
Even so, he was held to be disqualiﬁed to speak on the subject of tak-
ing action on the Gulf War because he would not personally suffer
from the consequences of such an action. The Gulf War argument is
more about consequences while the armored vehicles argument is more
about being personally in a position to know about something by hav-
ing practical experience of it. Despite these differences, there is a cer-
tain similarity between the two arguments, and both seem to fall under
the heading of situationally disqualifying ad hominem arguments, even
though the reasons for the situational disqualiﬁcation are diﬀerent.
The abortion argument seems similar to the armored vehicles argu-
ment in certain respects. In the armored vehicles argument, Lind is criti-
cized as not being in a position to make recommendations on the use of
armored vehicles because he has never served as a commander of such
vehicles in a military setting. He can’t see it from the soldier’s point of
view, and hence we are ‘‘wasting time’’ listening to his argument. In the
abortion argument, men are being disqualiﬁed because they can’t see it
from the woman’s point of view. The reason given is that impossible
for the man to be in this situation. Presumably this means that it is
impossible for the man to be in the situation of having an unwanted
pregnancy. Because the man can’t have this experience personally, he is
not in a position to know about abortion, and therefore he can’t speak
about it from direct knowledge. So whatever any man might say on
the abortion issue, we are wasting our time listening to it, or taking his
argument seriously. Thus interpreted, the abortion argument seems to
be similar to the armored vehicles argument. Since the latter is classiﬁed
above as an example of the situationally disqualifying ad hominem
argument, maybe the abortion argument should be too.
The Gulf War argument seems a little different from the armored
vehicles argument in that it, like the abortion argument, rests on a
premise about being in a position to know about something. The
argument seems to be that if a person isn’t in a position to know
about something, by having personal hands-on experience of it, then
they can’t really talk about it. Or if they do speak about it, we need
not pay any attention to what they say. The Gulf War argument
seems to have a different basis. The argument there is that if an arguer
doesn’t have a direct interest at stake in an issue, he is disqualiﬁed
from talking about that issue, in a way that ought to command our
paying attention to what he says. Since the Major General is retired,
and will not have to risk his life in war, he can’t make any recommen-
dation on whether the country ought to go to war or not. This argu-
ment seems weaker than the others, or easier to refute. One might
argue that decisions on whether to go to war are rightly made by
POISONING THE WELL 283
those who have more experience with such things, and these often tend
to be people who are now too old to actually ﬁght on the front lines
any more. But that might not be such a bad thing, or at any rate, an
argument for it could be made.
Still, no matter how one might try to compare these four arguments
at this point, a number of problems are posed. How should they be
classiﬁed, as poisoning the well arguments or as situationally disquali-
fying ad hominem arguments? Are these two categories really distinct?
Are they both species of ad hominem arguments? After all, it is not
obvious how or whether they are based on or involve attacks on an
arguer’s character. But if they are ad hominem arguments of some sort
or sorts, how exactly do they ﬁt into this category? Are they fallacious
arguments? Or might they have something about them that is some-
what reasonable, at least up to a point? For pointing out an arguer’s
bias, or his lack of personal experience about something, can some-
times be a reasonable way of criticizing an argument he has put for-
ward. In general, the problem with ad hominem arguments is that,
although traditionally categorized as fallacious, they often have some
basis of inherent reasonableness in them that should not be entirely
3. TYPES OF AD HOMINEM ARGUMENTS
Argumentum ad hominem is generally taken in logic textbooks to refer
to a personal attack on an arguer used to claim that her argument
should be given reduced credibility. The expression argumentum ad
hominem is widely used in common speech where it is commonly taken
to refer to the use of personal attack by one party in a dialogue to
impugn the character of another party. The expression ‘personal
attack’ means that the one party alleges that the other party has a bad
ethical character. For example, the party attacked may be called a liar,
or some other emotively negative language may be used to indicate a
character fault worthy of condemnation. The most common subtypes
of ad hominem featured in the textbooks are the abusive ad hominem,
the circumstantial ad hominem, the bias type, the tu quoque type and
the poisoning the well type (Walton, 1998). In the abusive ad hominem
attack, it is straightforwardly claimed that the arguer has a bad char-
acter, and that therefore some particular argument she had put for-
ward earlier should be discounted or rejected. Often a bad character
for veracity is emphasized, which suggests that an arguer can’t be trus-
ted to tell the truth. In many cases, such a suggestion can have quite
an impact on how an audience would judge a person’s argument, as
one can easily appreciate. For example in political argumentation, or
in the case of a witness in a trial, whether the speaker’s argument is
284 D. N. WALTON
credible may depend on how honest or reliable we take her to be.
Even a small suspicion raised against her character can have quite a
large eﬀect on how an audience judges her argument or testimony. A
small whiﬀ of scandal can prejudice an audience. Indeed, many ad
hominem arguments are so powerful precisely because of this ‘‘smear
eﬀect’’. Even a poorly substantiated innuendo leaves an audience with
a lingering feeling of distrust and suspicion, raised by the personal
The history of the ad hominem contains an ambiguity that has led
to some confusion in textbook treatments. In the textbooks, that argu-
ment is mostly interpreted as a personal attack, as outlined above, But
there is also a meaning of ad hominem which takes it to mean an argu-
ment ex concessis that uses an arguer’s commitments (previous conces-
sions) to try to maker her follow a certain line. This meaning of ad
hominem is found in Locke, Galileo, and Johnstone, but it can be
traced back to Aristotle.
The ex concessis type of argument is distinc-
tively diﬀerent from the argumentum ad hominem, but is related to it,
especially to the circumstantial subtype. Let’s call the party putting
forward the original argument the proponent and the other party, who
carries out the personal attack, the respondent. The direct form of the
argumentum ad hominem, often called the abusive ad hominem, is rep-
resented by the following argumentation scheme. It is better to call it
the direct ad hominem because ‘abusive’, being a negative term, sug-
gests that this form of argument is always fallacious.
3.1. Argumentation scheme for the direct ad hominem argument
The respondent is a person of bad (defective) character.
Therefore the respondent’s argument should not be accepted.
Direct ad hominem arguments work because an attack on a respon-
dent’s character, say for honesty, sincerity or trustworthiness, can
undermine the his credibility as a source. And credibility as a source is
sometimes important as a reason for accepting a claim. But not all
attacks on character should be classiﬁed as ad hominem arguments. To
qualify as an ad hominem argument in the logical meaning of the term,
the character attack must be used by the proponent to try to refute an
argument previously put forward by the respondent.
Personal attack in argumentation is not inherently fallacious, and it
has long been recognized, for example, in political argumentation, that
a speaker’s perceived goodness or badness of character is a major fac-
tor that will affect how audiences will take his arguments, and judge
them to be persuasive or not. And indeed, if a person has a bad char-
acter for veracity, for example a witness in a criminal case, then
POISONING THE WELL 285
attacking that person’s character in order to make his or her testi-
mony seem less plausible to a jury can be a reasonable form of argu-
ment. For example, in legal argumentation, it can be ruled admissible
as evidence for an attorney cross-examining a witness to attack the
character of the witness for honesty. Because this type of argument is
sometimes legitimate, it is something of a misnomer to call it the
‘‘abusive’’ ad hominem argument. In Aristotle’s Rhetoric (Garver,
1994), argument from ethos (character) was regarded as highly impor-
tant in public speaking, and in rhetoric of all kinds, and was recog-
nized as a legitimate kind of argumentation. The following
argumentation scheme for the negative ethotic type of argument was
given in (Walton, 1995, p. 152), along with a set of critical questions
matching the scheme.
3.2. Argumentation scheme for the negative ethotic argument
ais a person of bad character.
Therefore a’s argument ashould not be accepted.
3.3. Matching critical questions
: Is the premise true (or well supported) that ais a person of bad
: Is the issue of character relevant in the dialogue in which the
argument was used?
: Is the conclusion of the argument that ashould be (absolutely)
rejected even if other evidence to support ahas been presented, or
is the conclusion merely (the relative claim) that a should be
assigned a reduced weight of credibility, relative to the total body
of evidence available?
So, as suggested above, it is appropriate to re-name the abusive ad
hominem type of argument and call it the ethotic type of ad hominem
argument (or purely ethotic) to distinguish it from the circumstantial
and bias subtypes. Or if the ‘‘abusive’’ label is retained, it could be
reserved for the fallacious instances, where the ethotic argument has
been misused. Thus the thesis proposed here is that the direct, or
so-called abusive ad hominem is identical to the negative ethotic
In the circumstantial type of attack, some personal circumstances of
the arguer (very often, actions that she has performed) are cited as
being in conﬂict with what she advocates in her argument. Political
campaign advisers are particularly adept at deploying this type of
argumentation. For an argument to qualify as a circumstantial ad
286 D. N. WALTON
hominem, it must meet two key criteria, on the above analysis. It must
be based on an allegation of inconsistency, and this allegation must be
the basis of a personal attack. What is most controversial about
the system of classiﬁcation proposed above is that it goes against the
conventional wisdom that any argument attacking another argument
as inconsistent comes under the ad hominem heading. On the system
proposed above, this classiﬁcation is too broad. On this new system,
an ad hominem argument, even a circumstantial one, must be a
personal attack. This is taken to mean that it must be an attack on the
arguer’s ethical character, for example her character for honesty. If
not, then it is not an ad hominem argument, in the technical sense
proposed here for logic as a discipline. But this recommended techni-
cal sense of the term, at least arguably, preserves the commonly
accepted meaning in English of the expression ‘ad hominem argument’.
Attacks on an arguer on grounds of bias are often classiﬁed under
the ad hominem heading. For example, in Hurley (2003), all the exam-
ples classiﬁed under the circumstantial ad hominem category ﬁt very
nicely into the argument from bias category. In the bias type of
attack, the arguer is said to have a personal bias, often in the form of
a ﬁnancial interest or something to gain. For example, suppose a
speaker in an environmental debate, who has played down the damage
of acid rain in the debate, is shown by her opponent to have ties with
a large industrial corporation. This corporation may have much to
lose by costly environmental controls that might be placed on indus-
3.4. Argumentation scheme for argument from bias (Walton, 1998, p. 255)
If xis biased, then xis less likely to have taken the evidence on both
sides into account in arriving at conclusion A.
Arguer ais biased.
Arguer ais less likely to have taken the evidence on both sides into
account in arriving at conclusion A.
Such a bias ad hominem attack might have quite an eﬀect on the audi-
ence judging the worth of the speaker’s arguments in the debate. This
kind of attack is even more powerful when it suggests that the arguer
so attacked is not fairly considering the arguments on both sides of the
issue, but has made up her mind at the outset, and is always pushing
for the one side. Thus the worth of her future arguments are all deva-
lued, even before they are advanced. Thus there is a close connection
between arguments from bias and poisoning the well. If the bias alleged
is used to argue that the person has a bad character, the bias argument
can then become an ad hominem argument. For example a pattern of
POISONING THE WELL 287
bias may be used as evidence to argue that the person attacked is not
honest, sincere or reliable in taking part in a collaborative discussion.
Like many other types of ad hominem arguments, the attack can be
on the arguer’s credibility as a person who can be trusted to sincerely
take part in a dialogue exchange. Many types of dialogue require
collaboration in accepting arguments that are based on good evidence,
and accepted not just because they support your own position or per-
sonal interests. In a negotiation dialogue, interests loom large. But in a
critical discussion or an inquiry, ﬁnding the truth should matter more.
If a person keeps bending the evidence to her own interests, she can be
open to a bias type of ad hominem attack that could be quite a legiti-
What needs to be emphasized here is that the bias type of ad homi-
nem argument, as well as argument from bias generally, are not neces-
sarily fallacious. For example, such arguments are often allowed in
court when an attorney is cross-examining a witness. The character of
the witness for honesty (veracity) is held to be relevant in trial rules
like the Federal Rules of Evidence. If the witness is being paid to tes-
tify for one side, the attorney has the right to ask her about whether
she is being paid to testify. Such a question is allowed, even though an
admission to this eﬀect will have an eﬀect on how the jury will weigh
the plausibility of what she says, and the strength of the arguments
To sum up then, the system of classiﬁcation proposed here is that
there are three basic types of ad hominem argument, the direct (nega-
tive ethotic) type, the circumstantial type, and the bias type. All of
them have historically been identiﬁed with argument from commit-
ment. The latter two types have been identiﬁed with respectively with
argument from inconsistent commitment (of the two kinds identiﬁed
above) and argument from bias. It has been argued here that this old
way of classifying such arguments is incorrect. To be an ad hominem
argument, the given argument must be a personal attack. That is, it
must be an attack on the arguer’s character used to discredit her argu-
ment. Now we can go on to examine the fourth category of commonly
recognized ad hominem argument, the poisoning the well type.
4. POISONING THE WELL AND ALLEGING GROUP BIAS
My original hypothesis was that the poisoning the well type of argu-
ment should be classiﬁed as a species of ad hominem argument.
In (Walton, 1995, p. 213) it was argued that the poisoning the well
type of ad hominem argument is best treated as an extension of the
bias type of ad hominem argument. The diﬀerentiating factor cited
(Walton, 1995 p. 215) is that in the poisoning the well type of ad
288 D. N. WALTON
hominem argument, the bias is alleged to be of the type that the per-
son attacked can never change, or at least cannot practically change as
far as the circumstances relevant to the argument are concerned. For
example if someone is said to be biased because of gender that is a
factor that is not subject to change at least practically speaking, with
respect to the argument.
The problem is that no matter how far such
person is balanced and fair in his argumentation, whatever he says in
the future will be clouded by this allegation of bias. Thus the poison-
ing the well type of ad hominem attack can be described as a tactic
that diﬀuses a discussion by disqualifying the attacked person from
taking further meaningful part in it with any credibility.
Subsequent investigations have convinced me that the poisoning
the well type of argument is more complex than it initially appeared
to be. Much depends on how the ad hominem type of argument is
deﬁned, but the problem is that once we start investigating actual
cases classiﬁed as instances of poisoning the well, we can see that
some of them are less well classiﬁed as ad hominem arguments than
others. The theoretical problem is similar to that discussed above in
relation to arguments from inconsistency and bias. The issue is whe-
ther such arguments should properly be classiﬁed under the ad homi-
nem heading. According to the analysis given in (Walton, 1998, pp.
257–258) there is a poisoning the well type of argument should be
deﬁned as a distinctive type of argumentation scheme in its own
4.1. Argumentation scheme for poisoning the well by alleging group bias
Person ahas argued for a thesis A.
But abelongs to or is aﬃliated with group G.
It is known that group Gis a special-interest partisan group that takes
up a biased (dogmatic, prejudiced, fanatical) quarrelling attitude in
pushing exclusively for its own point of view.
Therefore, one cannot engage in open-minded critical discussion of
an issue with any members of G, and hence the arguments of afor A
are not worth listening to or paying attention to in a critical discussion.
4.2. Matching critical questions
CQ1: Has agiven any good reasons to support A?
CQ2: What kind of bias has aexhibited, and how strong is it?
CQ3: Is the kind of bias that ahas exhibited a good reason for concluding
that she is not honestly and collaboratively taking part in the dialogue?
CQ3: Is there evidence of a dialectical shift in the case, for example, from
a persuasion dialogue to a negotiation?
POISONING THE WELL 289
CQ4: Is the bias indicated in CQ2 of the very strong type that warrants
the conclusion that ais not open to any argumentation that goes
against her position (or seems to her to go against her position)?
This form of argument could be called the PWAGB (poisoning the
well by alleging group bias) type. It is characteristically present in
many cases of ad hominem arguments to be sure. But it also turns out
to be present in many cases of argument from bias that should not
properly be classiﬁed under the ad hominem category. One can easily
criticize another party’s argument by alleging that it shows a bias
without the argument being a personal attack on the other party’s eth-
ical character. Yet of course, in many instances the bias argument is a
lead-in to an ad hominem attack. This diﬀerence can be discussed by
examining the two standard cases we began with.
The two cases classiﬁed as instances of poisoning the well in section
‘Poisoning the well’ exhibit some key differences. Cardinal Newman
evidently took the argument used against him by Kingsley as an ad
hominem attack, because Kingsley used the argument to suggest that
Newman, as a Catholic, had no regard for the truth of any matter
being discussed. Without examining the details of Kingsley’s text, it
may be fair to assume that Newman was quite right to take it in this
way. Interpreted in this way, the argument suggests that Newman is
intellectually dishonest, a person who will put other considerations,
like church interests, before the truth of a matter being discussed.
Taken this way, the argument is that Newman is not trustworthy as
an arguer who will admit defeat in a critical discussion, even if
the evidence presented to him in the discussion is clearly shown to log-
ically refute his opinion. Thus interpreting the argument in this way, it
is true to say of it that an aspect of Newman’s ethical character was
being attacked – his character for intellectual honesty.
The abortion argument appears to be different in its aim, in that
it is not an attack on an arguer’s ethical character that uses that
attack to try to refute his argument. The arguer is not attacking any
individual man who disagrees with her position on abortion and
claiming he is a liar, or is not trustworthy. No individual person’s
character is being attacked, as far as we can tell. Instead, all men are
being attacked as a group, and their capability for entering into a
discussion that can fully represent both sides of the abortion issue is
being attacked holistically. It is a classic PWAGB argument. But it is
not an ad hominem argument, according to the schemes laid out
above. Thus a subtlety revealed by these two cases is that in some
cases the poisoning the well argument is not an ad hominem argu-
ment while in other cases it is. The two can be combined in some
instances, and this form of argument has been recognized in the
literature (Walton, 1998, p. 255).
290 D. N. WALTON
4.3. Argumentation scheme for poisoning the well as ad hominem argument
For every argument ain dialogue D, person ais biased.
Person a’s bias is a failure to honestly take part in a type of dialogue
D, that ais part of.
Therefore ais a morally bad person.
Therefore ashould not be given as much credibility as he would have
without the bias.
Therefore ashould be discounted (taken as less plausible than before).
4.4. Matching critical questions
CQ1: What is the evidence that ahas been biased with respect to every
argument in the dialogue?
CQ2: Is the bias a normal partisan viewpoint that ahas shown, or can
it be shown to indicate that ais not honestly participating in the
CQ3: In what respect is aa bad person, judging from the evidence of his
participation in the dialogue that gives a reason for doubting his
The difference between the two cases concerns a wider and a nar-
rower meaning of argumentum ad hominem. The narrower sense of
argumentum ad hominem requires that the argument must be a per-
sonal attack on the individual arguer’s ethical character. In this sense
of the term, there must be two arguers, and one must attack the argu-
ment of the other by attacking his character. The broader sense does
not require a character attack against a speciﬁc arguer. It only
involves the inclusion of any arguer that might be opposed to one’s
viewpoint in a group, and a preemptive dismissal of the whole group
as having the capability for engaging in rational argumentation. The
basis of the dismissal is that the group as a whole has to be biased
because they lack some kind of capability of being able to appreciate
or consider the arguments on both sides.
Despite this key difference, the two arguments have much in com-
mon. Both are based on the membership of the opponent in some
group, and it in light of some alleged characteristic of this group as a
whole that the individual opponent’s arguments are discounted. Both
are group attack arguments. However, even here there is a difference
to note. Newman has voluntarily joined the group of Catholics, and
presumably, he can leave it at any time. Being a man is not something
that can be changed, at least so easily. You could have a sex change
operation. But even if you did that, you still might not be able to see
POISONING THE WELL 291
the abortion from the woman’s point of view. So this argument is
based on a group membership that is ﬁxed by factors, biological char-
acteristics, that are outside of an arguer’s control. In this way, the
argument is more sweeping and perhaps more dangerous. It seems like
an even more sweepingly dismissive strategy of exclusion than the one
used in the Cardinal Newman argument. Any man who tries to sup-
port his viewpoint on the abortion issue by rational argumentation is
attacked and defeated, even before he can enunciate his argument.
Simply because he is a man, his argument is doomed to fail.
What these observations suggest is a new approach to poisoning the
well arguments. The ﬁrst hypothesis is that they are not always ad
hominem arguments, and can exist in their own right, separately from
ad hominem arguments. The PWAGB is a case in point. Also, it is pos-
sible that in the future other instances of poisoning the well arguments
that are not ad hominem arguments may be discovered. At the same
time, the Newman case shows that the poisoning the well type of argu-
ment can sometimes be rightly classiﬁed as species of ad hominem argu-
ment that is a subtype of the bias type. But the fact that it can exist in
its own right leads to the suggestion that it may represent a distinctive
type of argumentation tactic or device worth study in its own right.
What seems to be essentially characteristic of the poisoning the well
type of argument generally is that it has a diffusion effect in a dia-
logue between two parties. The dialectical situation can be described
as follows. First one party in the dialogue, called the proponent, puts
forward a particular argument. Then the second party, who we will
call the respondent, attacks the proponent’s argument by alleging
something about the proponent concerning his bias or his personal
credibility that disqualiﬁes him from putting forward any argument
that should carry with it any credibility. Such a reply has a diffusion
effect because it does not merely refute the opponent’s argument, it
destroys his capability for putting forward any argument on the same
subject, or perhaps even any argument on any subject, in the future
discussion. In the case of the Cardinal Newman argument, he felt very
threatened by the argument, even going to the extreme of writing a
whole book trying to disarm it. Evidently he felt that the argument
destroyed his capability for engaging in philosophical or political
discourse at any future time with any degree of credibility. And he
could well have been right. For such an argument can be extremely
powerful. It works by sowing doubt, often on the basis of a kind of
innuendo that destroys an arguer’s credibility.
Finally, a word must be added about whether PWAGB arguments are
fallacious or not. It seems that such arguments could be reasonable in
some cases, if the premises are supported by evidence. Obviously also,
they are very dangerous, because of the powerful effect they can have.
292 D. N. WALTON
They can also be associated with other forms of argument that are per-
haps even more dangerous.
5. IMPLICIT PREMISES
In commenting on this paper, David Hitchcock argued that the fault in
both leading cases of poisoning the well cited in section ‘Poisoning the
well’ is not so much that that their premises do not support their con-
clusion as that their premises are unjustiﬁed. Cardinal Newman did not
anywhere write that truth ought not to be a virtue for the Roman cler-
gy. Indeed, he himself was a Roman Catholic priest who prized truth
as a virtue. It is possible for a man to see abortion from a woman’s
point of view, because we have the ability to learn by empathy even if
we cannot experience directly what another person experiences. If this
criticism is right, these arguments fail only because their premises are
not justiﬁed, and that is no real ground for classifying them as falla-
cious. To show an argument is fallacious, one needs to show not just
that it is weak, or has unsupported premises, but that it uses some sys-
tematic deceptive argumentation tactic to get the best of a speech part-
ner unfairly. In section 7, this deceptive tactic notion on which the
concept of fallacy is based will be discussed, but here we need to return
to the Cardinal Newman example and the abortion example to respond
to the criticism that their premises are not justiﬁed.
Kingsley’s attack on Newman, and on Newman’s arguments about
matters of politics and the like, was indirect. He linked Newman and
his teachings to the view that truth should not be regarded as a virtue
by simply classifying Newman (correctly) as Catholic, and by arguing
at length that Catholics as a group do not prize truth. But the implicit
conclusion of his argument, that Newman does not prize truth, since
he is a Catholic, and Catholics do not prize truth, is a powerful
attack. It is an innuendo, rather than an explicit premise or conclusion
of Kingsley’s, but even so, it does a lot of damage. The reason is that
it disqualiﬁes Newman from taking part in any critical discussion of
any issue in which the participants need to put forward arguments
that they really believe are cogent, and need to be open to critical
questioning of these arguments. Otherwise, an arguer is not sincerely
taking part in a critical discussion. How such a powerful poisoning the
well attack exploits implicit premises to mount an innuendo can be
shown precisely in the following analysis of the argumentation in the
To begin to analyze the abortion argument, the basic propositions
that are taken to be its premises and conclusions must be identiﬁed.
These are identiﬁed in the following key list
POISONING THE WELL 293
5.1. Key list for the abortion argument
(A) It is not possible for men to get really emotionally involved in the
issue of abortion.
(B) It is impossible for a man to be in the situation of personally deciding
whether to have an abortion.
(C) It is impossible for a man to really see the abortion issue from the
woman’s point of view.
(D) There should be more women in this House available to speak about
the abortion issue from the woman’s point of view.
We use the software system Araucaria (Reed and Rowe, 2002)
to construct an argument diagram based on this analysis. So
diagrammed, the abortion argument can be visualized as a serial
294 D. N. WALTON
If we examine this argument carefully, we can see that premise B is
true, or at least it seems quite plausible, and there does not seem to be
much reason to disagree with it. The inference from B to A, however,
is weak, even though there is some basis for it. The generalization that
warrants the inference from B to A could be stated as follows.
(E) If it is impossible for someone to be in a situation of personally
deciding to do something or not then such a person can’t get really
emotionally involved in the issue.
Like many such generalizations, this one is hard to pin down to an
exact meaning until terms in it like ‘really emotionally involved’ are
Similarly, the inference from A to C seems weak, but there is some
basis for it. It seems to be based on a generalization something like
(F) If a person can’t get really emotionally involved in an issue, then it is
impossible for him to see the issue from the point of view of the other
side of those who are involved in it.
Thus the argument can be analyzed as an enthymeme in which E and
F are premises. Each of them goes together with an explicit premise,
and the structure of the whole argument can be diagrammed as
In this diagram, the two generalizations E and F are represented as
nonexplicit premises, and hence they are shown as shaded in the Arau-
caria diagram, differentiating them from the explicitly stated premises
of the abortion argument. Now these two implicit assumptions have
been brought to light, and the diagram has shown how they are used
to draw inferences in a chain of argumentation, we need to ask what
makes them plausible as assumptions.
It seems that the basis of these implicit premises and the way they
are used to generate inferences is based on an even more general
assumption about being personally in a position to know about some-
thing. This same aspect was at work in the examples of the situation-
ally disqualifying type of ad hominem argument studied above. If you
haven’t had personal hands-on experience about something, it seems
that an inference can be drawn that you are not really in a position to
speak about it on the basis that you are in a position to know about
it. This kind of inference is reminiscent of the argumentation scheme
called argument from position to know (Walton, 2002, p. 46).
5.2. Argumentation scheme for argument from position to know
Source ais in a position to know about things in a certain subject
domain Scontaining proposition A.
POISONING THE WELL 295
296 D. N. WALTON
aasserts that Ais true (false).
Therefore Ais true (false).
5.3. Matching critical questions
:Isain position to know whether Ais true (false)?
:Isaan honest (trustworthy, reliable) source?
: Did aassert that Ais true (false)?
The cases studied above, including the ones classiﬁed as situationally
disqualifying ad hominem arguments and the ones classiﬁed as poison-
ing the well arguments, are not position to know arguments, in any
straightforward sense. But they do have a position to know aspect.
They are negative arguments from a perceived failure to be in a per-
sonal position to know about something. Form this negative premise,
they draw a conclusion that has the eﬀect of disqualifying an arguer
from taking part in dialogue on an issue.
6. CLASSIFYING POSITION TO KNOW AND SITUATIONALLY
Now we come to the problems posed by the case studies and analyses
above concerning the classiﬁcation of the various argumentation
schemes. The ﬁrst one is that although many of these forms of argu-
ment can be combined with the argumentum ad hominem, they can
also exist in some cases as separate arguments in their own right. For
example, argument from bias can be combined with argumentum ad
hominem, producing the bias subtype, it can also exist as a separate
form as an argument on its own. Also, we will now proceed to show
that the two cases of the situationally disqualifying argument above,
as well as the abortion argument, should not be classiﬁed as ad homi-
nem arguments. This is assuming that no personal attack on the
arguer’s character is involved.
The ﬁrst thing to be aware of is how the poisoning the well argu-
ment works in a dialogue setting. It is not just a single refutation of
an arguer’s single argument. It damns the source and shuts down all
future arguments that the arguer who has been attacked by it might
put forward in the remaining part of the dialogue. Thus it is an
extremely powerful argument, and a hard one to defend against. Like
all such powerful argumentation strategies, this argument is not wholly
fallacious. It is based on a true premise. That premise is that the per-
son who is directly involved in a situation, and has been personally
affected by it, is in a special position to know about an issue about
that situation. While you can have empathy for another person’s situa-
POISONING THE WELL 297
tion, you can’t have the exactly same insight into that situation, and
experiences related to it, that the person directly involved has. The sit-
uationally disqualifying ad hominem argument is plausible partly be-
cause it rests on the same premise. The structure of the poisoning the
well type of argument can thus be seen in some instances as based on
a prior type of argument from lack of being in a position to know
that builds on such a premise.
6.1. Negative argument from position to know based on personal situation
Source ais not in a position to know about things on a certain issue I
because he does not or even cannot personally be in a situation to
have experienced such things.
Source aputs forward argument a.
ais about issue I.
Therefore argument acan be discounted.
This argument appears to be somewhat reasonable, as long as argu-
ment ais not discounted as being entirely worthless. Think of witness
testimony in law, where the someone who did see an event himself,
and was thus directly in a position to know exactly what happened,
can testify about what happened in the same way that someone who
did not see it cannot. Although this argument has a reasonable basis
in some cases, it can also be pushed too far. As David Hitchcock
pointed out, there is such a thing as communication between human
beings from different groups. We can learn by analogy what it is like
to experience things that we cannot directly experience ourselves.
Empathy is possible, and is surely the basis for argumentation that
rests on another party’s viewpoint in a critical discussion. Many legiti-
mate arguments, in cases where a conclusion has to be arrived at
under conditions of uncertainty and lack of ﬁrst-hand knowledge, are
based on this kind of indirect knowledge of something.
In addition, it needs to be noted that the poisoning the well type
of argument is different from negative argument from position to
know based on personal situation. It is an even stronger form of
argumentation covering three previous schemes.
6.2. Poisoning the well argument
Source ais not in a position to know or speak about things on issue I
because he does not or even cannot personally be in a situation to
have experienced such things, or is biased, or has bad character.
Therefore whatever asays on issue Ican be disregarded.
298 D. N. WALTON
In the poisoning the well argument, every argument that aputs for-
ward on issue can be disregarded as worthless. This includes all argu-
ments he might put forward in the future as well as those he has put
forward in the past. Thus this is a much stronger form of argumenta-
tion than negative argument from position to know based on personal
situation or than ad hominem.
Now we come to the question of how to judge whether arguments
falling into all the various types studied above are reasonable, strong,
weak or fallacious. The ﬁrst point to be made is that negative argu-
ment from position to know based on personal situation is not inher-
ently fallacious. It is a species of position to know argumentation that
tends to be weak, and that can easily go wrong by being taken as
stronger than it really is. But it does have some basis of reasonable-
ness. On the other hand, the poisoning the well type of argument,
although it is a species of this former type of argumentation, and as
such has some rational basis, is an extremely dangerous form of argu-
mentation. It goes too far. It starts from what could be true premises,
in some cases, but then moves ahead drastically to shut down the
attacked arguer’s capability for taking any meaningful part in a dis-
cussion. This is a kind of fallacy. The modus operandi of it is compa-
rable to that of the ad verecundiam fallacy, where an arguer’s
arguments are disregarded as entirely worthless because he is not an
expert in a domain of knowledge on the issue being discussed. This is
a tactic used to try to shut somebody up.
Having arrived at this general conclusion about poisoning the well
as a fallacy, there are several other points of contention that also
require attention. How does the fallacy actually work, for example in
the abortion argument? It works because the basically reasonable neg-
ative argument from position to know is posed in stronger form in
individual cases that makes it ﬁt the poisoning the well scheme. But
the stronger version of the argument can be concealed through the use
of implicit premises, making the argument an enthymeme. Let us
examine once again the implicit premises identiﬁed in the analysis of
the abortion argument brought to light in the diagram above.
(E) If it is impossible for someone to be in a situation of personally
deciding to do something or not then such a person can’t get really
emotionally involved in the issue.
(F) If a person can’t get really emotionally involved in an issue, then it is
impossible for him to see the issue from the point of view of the other
side of those who are involved in it.
The problem with these generalizations as warrants for the inferences
drawn in the chain of argumentation in the abortion argument is
that they are weak. Consider E ﬁrst. Suppose my mother is terminally
POISONING THE WELL 299
ill with cancer and she has to decide whether to take chemotherapy or
not. It’s her decision, but that isn’t to say that I can’t get ‘‘really emo-
tionally involved in the issue’’. Now consider F. Suppose I am a medi-
ator in divorce dispute. I am not supposed to get emotionally
involved, as a mediator, or to take sides. Yet I am supposed to see the
issue from the point of view of the one side as well as that of the
other side. Thus the problem with E and F is that they deny the possi-
bility of skills that are admittedly difﬁcult to achieve, but that are nec-
essary if argumentation of various important kinds is to be useful in
This form of argument is represented by the argumentation scheme
for the situationally disqualifying argument exhibited in section 2
above. On the other hand, it is possible to have a situationally dis-
qualifying type of ad hominem argument. Such an argument has to
meet the requirements for the argumentation scheme below (Walton,
1998, p. 258).
6.3. Scheme for the situationally disqualifying type of ad hominem
In dialogue D,aadvocates argument a, which has proposition Aas its
ahas certain features in his personal situation that make it inappropri-
ate for him to make a dialectical contribution to D.
Therefore, ais a morally bad person.
Therefore, a’s argument ashould not be accepted.
6.4. Matching critical questions
CQ1: What features of a’s personal situation make it inappropriate for
him to contribute to D?
CQ2: Do the features of a’s situation cited give any good reason to make
one conclude that it is inappropriate to contribute to D?
CQ2: Could a’s argument be worth considering on its merits, even though
there is reason to think them inappropriate for D?
The leading example of this type of argument is the Cardinal Newman
argument, assuming that Newman’s character for honesty was being
attacked. Here then is a key difference between the Cardinal Newman
argument and the abortion argument. The former is a poisoning the
well ad hominem argument while the latter is a poisoning the well
argument but not an ad hominem argument.
Now we must turn to the situationally disqualifying type of argu-
ment, as represented by the examples of the Gulf War argument and
300 D. N. WALTON
the armored vehicles argument presented in section 2. To analyze these
examples in the best possible way, utilizing the schemes set forth
above, it seems necessary to take the step of revising their classiﬁca-
tion. They don’t seem to be ad hominem arguments since they do not
appear to include a negative ethotic attack on the arguer’s character,
in either instance. If this interpretation of the text of discourse of ei-
ther case is right, then the argument in each is not properly an ad
hominem argument, even though it is a situationally disqualifying
argument. This conclusion is a signiﬁcant one, and requires a revising
of the classiﬁcation of this form of argumentation in the earlier litera-
The poisoning the well argument turns out, therefore, to represent
quite a complex type of argumentation, combining the negative posi-
tion to know argument with the argument from bias in many instances,
or using either separately, and often combining one or both of these
with the argumentum ad hominem. The ﬁrst problem with any case of
poisoning the well is to identify the type of argument more precisely by
analyzing the individual case to arrive at a hypothesis on how to judge
which argumentation scheme or schemes are appropriate to represent
the argument. The other problem is that many of these arguments can
be reasonable in some instances, so an evaluation of the argumentation
needs to be made. An assessment needs to be made on whether the pre-
mises of the argument are true (or acceptable based on the known evi-
dence), and whether the conclusion follows from the premises. Such
arguments tend to be best classiﬁed not as being deductively valid or
inductively strong. Rather they are meant to carry some weight as evi-
dence to shift a burden of proof in a dialogue, and are defeasible argu-
ments that should properly be seen as open to critical questioning. But
if they shut down a dialogue, by impeding the asking of such questions,
by impugning the source as biased or as not being in a position to
know about the issue being discussed, they can be fallacious. The key
to poisoning the well is that it shifts from the evidence presented by an
argument to the arguer herself. This is true with other forms of argu-
ment that are source-based as well, like ad hominem, appeal to expert
opinion, and appeal to witness testimony. Poisoning the well ﬁts
well with argumentum ad hominem because this type of argument is
negative – ad hominem works by discrediting the source. It does this by
arguing from negative position to know or by argument from bias. But
poisoning the well is a special type of argumentation tactic because it
not only attacks the credibility of the source, it has a way of discredit-
ing whatever the source says in the future of discussion on an issue.
The source is not only discredited, but is even disqualiﬁed from taking
any further meaningful part in a discussion. Such arguments, however,
contain the seeds of their own destruction.
POISONING THE WELL 301
For example if a proponent argues that a respondent is disqualiﬁed
to speak on the issue of abortion because he is a man, and is therefore
not in a position to know about abortion, the respondent can always
reply that the proponent, as a woman, will always be biased in favor
of the position representing the woman’s point of view. Thus the best
way to reply to a poisoning the well is often to use a tu quoque strat-
egy by devising an opposed poisoning the well argument. Unfortu-
nately, however, this reply tends to lead to an eristic dialogue in which
each side attacks the credibility of the other. The danger is that the
discussion on the issue is eﬀectively stopped as the argumentation
shifts to a diﬀerent kind of dialogue.
7. DIALECTICAL ANALYSIS OF POISONING THE WELL
There may be nothing wrong with arguing that an opponent’s argu-
ment should be discounted because he has lied, or otherwise shown
dishonesty and disregard for the truth of matter being discussed. The
many forms of ad hominem argument we have examined can often be
reasonable. But there is a danger of using rhetorical tactics of this sort
that that they can be so powerful in many instances that they can shut
down a discussion by poisoning the well. Johnstone (1981, p. 310)
identiﬁed the basic imperative of ethical rhetoric by stating this princi-
ple: ‘‘So act in each instance as to encourage, rather than suppress, the
capacity to persuade and to be persuaded, whether the capacity in
question is yours or another’s.’’ This principle was a predecessor of
rules for critical discussion set out by van Eemeren and Grootendorst
(1984, 1992, 2004), and formulates a duty of openness in rational
argumentation. By seeing his principle of openness as incompatible
with fallacious moves like appeals to force or threats in place of
rational persuasion (p. 311), Johnstone also paved the way for a solu-
tion to the problem of understanding why poisoning the well argu-
ments can be both rhetorically powerful and yet fallacious. Although
parties engaged in a critical discussion are committed to norms instru-
mental for achieving a successful outcome of the process, they are also
interested in resolving the issue by winning the argument (van Eemer-
en and Houtlosser, 2002, p. 134).
As shown in the analyses of the argumentation in the Cardinal
Newman example and the abortion example above, the poisoning the
well fallacy in each case is not easy to diagnose. First, the structure of
the arguments as a set of premises and a conclusion has to be ana-
lyzed, exhibiting an implicit premise that is inadequately supported.
This weak implicit premise, however, is not all there is to explaining
the fallacy. The fallacy resides in the use of the premise as part of
argument that mounts an innuendo, suggesting that the arguer is
302 D. N. WALTON
somehow dishonest or biased in way that disqualiﬁes him from taking
him from taking part in a critical discussion. The attack knocks his
argumentation out by disqualifying whatever he says henceforth as
tainted and illegitimate, thus shutting off any future critical discussion.
David Hitchcock articulated this dialectical analysis of the fallacy in
the Cardinal Newman example by stating that the personal attack al-
leged a fault so sweeping that its target is left in a position of being
unable to refute the allegation: ‘‘A person who is alleged to believe
that truth ought not to be a virtue cannot protest that he prizes truth,
since he has already been stigmatized as a person whose word cannot
be trusted’’. Having a critical discussion requires that each side can
have insight into the position of the other side, and that such insight
into the other’s viewpoint is improved through the discussion. This
possibility is precisely what the poisoning the well type argument is
designed to shut down. This insight about how poisoning the well
works as a powerful device of strategic maneuvering (van Eemeren
and Houtlosser, 2002) leads to the necessity of taking a dialectical
approach to analyzing it as a fallacy.
It would not be completely right to say that poisoning the well is
an interesting fallacy to study because it is included in the logic text-
books. A better reason is that it is interesting because it works so
well as a sophistical tactics type of fallacy. It is a powerful way of
knocking someone out of contention in an argument even if, or espe-
cially if, he has advanced a good argument. Poisoning the well is
associated with several forms of argument that can be fallacious, but
it is not any particular argumentation scheme itself that is fallacious.
The fallacy is dialectical one that is a violation of Johnstone’s princi-
ple requiring a participant in a discussion to act in each instance so
as to encourage, rather than suppress the capacity to persuade and
to be persuaded. The poisoning the well fallacy is committed in the
argumentation stage of a discussion, but the root of it is in the
earlier stages of the dialogue, the confrontation stage and the open-
ing stage. According to van Eemeren and Grootendorst (1992, p. 35),
a critical discussion has four stages. At the confrontation stage, the
one party to the dialogue puts forward a viewpoint and the other
party questions it, thereby making clear that there is a dispute to be
resolved. At the opening stage, the decision is made by both parties
to resolve the dispute by means of argumentation following proce-
dural rules. At the argumentation stage, the proponent defends his
viewpoint by putting forward arguments, and the respondent criti-
cally questions this argumentation and poses counter arguments. At
the concluding stage, it is established whether the dispute has been
resolved, so that one party is obliged to withdraw its viewpoint and
accept the viewpoint of the other side.
POISONING THE WELL 303
The normative basis for the fallacy of poisoning the well is essen-
tially established by the requirement of the argumentation stage that
the proponent should defend his viewpoint by putting forward argu-
ments that supports his viewpoint. The critical discussion works very
well only if the proponent puts forward the most important and per-
suasive arguments that are relevant to support his viewpoint and, and
the respondent actively critically questions these arguments, pointing
out weaknesses in them and posing signiﬁcant counter-arguments that
can be used against them. This function can only be fulﬁlled if the
proponent is allowed to put such arguments forward. If the proponent
is prevented from putting such arguments forward by excluding or
devaluing them in advance, the critical discussion stands no chance of
successfully proceeding through the argumentation stage and arriving
at the concluding stage. These requirements for success of the argu-
mentation stage are clearly speciﬁed in the confrontation stage and the
opening stage. It is clearly stated that requirements set by these earlier
stages are that the proponent should advance arguments that defend
his viewpoint, so that given the conﬂict of opinions, the other side can
then challenge this defense of the viewpoint by mounting criticisms
and relevant counter-arguments.
The poisoning the well fallacy is a strategy used by the respondent
to block proper fulﬁllment of this function at the argumentation stage
by violating the requirements set at the confrontation stage and the
opening stage. Blocking this function can be done in various ways.
Many of the most common of these ways are associated with other
informal fallacies, and with argumentation schemes that are at the
basis of these fallacies. However the fallacy of poisoning the well
should not itself be identiﬁed with any single one of these fallacies, as
is commonly done in the logic textbooks, for example by classifying it
as a subcategory of ad hominem fallacy. It is a dialectical fallacy asso-
ciated with a strategy of systematically blocking the main function of
the argumentation stage by violating the norms set to make fulﬁlling
that function possible in the prior two stages. Thus it is a dialectical
fallacy. Having said that, however, it is important to repeat that it is
closely allied to several of the other major fallacies, and to the argu-
mentation schemes that underlie them. Thus it is important to study
the relationships within this group of fallacies by examining their over-
Van Eemeren and Grootendorst have made no speciﬁc comments on
the fallacy of poisoning the well, as far as I can tell, but they did offer a
dialectical analysis of the ad hominem fallacy that could perhaps be
extended to it. On their analysis (1984, p. 191), the ad hominem fallacy is
not purely an inferential failure, but a dialectical failure of an argument
to meet the normative requirement of a critical discussion that the
304 D. N. WALTON
participants have an unconditional right to advance or criticize any
viewpoint. On their account (p. 192), the analysis of the ad hominem fal-
lacy ‘‘presents considerable diﬃculties’’ if it is ‘‘linked exclusively to the
invalidity of the arguments’’ put forward by the proponent. Their anal-
ysis gets around these diﬃculties by linking their analysis of the ad
hominem fallacy to ‘‘rules relating to the opening stage’’. Van Eemeren
and Grootendorst (2004, p. 178) remarked that all three variants of the
ad hominem fallacy they studied ‘‘can be used to silence (their italics) the
other party in the presence of a third party’’. They see the abusive and
circumstantial variants as violations of the rules of a critical discussion
entitling an arguer to put forward and challenge arguments of the other
party: ‘‘That the other party is a bad person or has a ﬁnancial interest in
winning the discussion is no valid reason for the protagonist to refuse to
take up that party’s challenge’’. The hypothesis suggested here is that
the dialectical type of analysis of the ad hominem fallacy put forward by
van Eemeren and Grootendorst can be extended, in a modiﬁed form, to
encompass the poisoning the well fallacy.
The poisoning the well strategic maneuvering in a dialogue can only
be understood fully by grasping the tension between pursuing a dialec-
tical versus a rhetorical goal in a crucial discussion Parties want to pro-
duce the most persuasive arguments they can at the argumentation
stage, but they must be presumed to hold to agreements made earlier in
the dialectical sequence linking the two prior stages to the argumenta-
tion stage (van Eemeren and Houtlosser, 2002, p. 135). Based on this
model of a fallacy as a derailment of strategic maneuvering, an argu-
ment should only be properly judged fallacious if it fails to allow com-
mitment to reasonable exchange of argumentative moves appropriate
for a stage of a dialogue. On this basis an argument commits the fal-
lacy of poisoning the well if it is used as a tactic to shut the other party
up and prevent him from taking any further meaningful part in the dia-
logue. The case studies in this paper have revealed why such an argu-
ment should not be classiﬁed as an instance of the poisoning the well
fallacy only because it is a weak inference, or has poorly supported pre-
mises in an argumentation scheme for an ad hominem argument, a bias
argument, or an argument of one of the other types studied above.
I would like to thank the Social Sciences and Humanities Research Council of Canada
for a grant that helped to support the research in this paper, and to thank David Hitchcock
and an anonymous referee for comments that helped me to make many revisions. The com-
ments of David Hitchcock were so penetrating and useful at so many points that they led to
a complete restructuring of the methodology and conclusions of the paper. To account for
his collaboration in reformulating key points, I have, in some instances, taken the unusual
step of quoting his remarks or attributing his critical comments by naming the source.
POISONING THE WELL 305
Generally the proponent is designated ‘she’ and the respondent ‘he’ in dialogues, but from
time to time the gender is chosen that leads to the least confusion for purposes of exposition.
David Hitchcock pointed out that Kingsley did not actually argue that Newman’s future
claims were not be trusted, but rather attributed to Newman the claim that truth need not
and ought not to be a virtue with the Roman clergy. On this interpretation, Kingsley’s argu-
ment was part of a broad attack on Roman Catholicism, and was not used to make claims
about Newman speciﬁcally. The reader can judge for herself by examining the original text
of the argument (Correspondence, 1864). If this interpretation of the text is correct, the
description of the case by Copi and Cohen should be revised to indicate that there was no di-
rect ad hominem argument against Newman, but rather an indirect and implicit attack.
This example, found by one of my students, Peter Campbell, is taken from a discussion
board on military topics: http://forums.military.com/1/OpenTopic?a=tpc&s=78919038&f
Johnstone (1959, 1978) deﬁned argumentum ad hominem as argument from commitment
of a kind that could be reasonable in many instances, even though it has traditionally been
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to be always fallacious, but should, in many common cases, be seen as reasonable but
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POISONING THE WELL 307