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bonjour! my name is Natalie Bouchard. I am a PhD student in Cognitive Science / Philosophy at Université du Québec à Montréal. My research is about the influence of the olfactory memory over our spatiotemporal perception of the environment. Can I learn more about your research on Odor perception in space? thank you.

Philosophers or scientists aim to define unifying theories to explain as much as possible numerous phenomena based on a few principles. Philosophers might for instance state that two phenomena separated in time or space always differ in at least one scale of analysis or perception. Individual particles, like bosons or fermions, might be unique immeasurable physical expression because of Heisenberg principles. Physical expression combining these particles at higher levels of organisation should therefore also be unique in physical expression. Thus, two grains of sand on a beach or two oxygen atoms might never be structurally exactly the same at all scales of analysis. In addition, because phenomena will probably be perceived differently by organisms with different biology, philosophers might state that for at least one scale of analysis two phenomena will never be perceived exactly the same by different observers. Because phenomena might be material, objects or living beings all these philosophical statements would cover any spatiotemporal scale in distinct science disciplines, including Physics, Chemistry or Biology.

This would imply that physical, chemical or biological structures are physically always 'un-replicable' or perceived as 'un-replicable. Are 'replicable' phenomena as defined in science practice not more than human mental products disconnected from the true nature of nature? Scientists might for example accept 'imprecisions' when they define classes or groups of phenomena with common characteristics to make them 'replicable'. Do scientists invent artificial rules to make science practice workable from an empirical or mathematic point of view?

The Master of Königsberg famously differentiated between what is given in perception by the senses (the "phenomenon") and the thing-in-itself, the Ding an sich (the "noumenon") – cf. http://en.wikipedia.org/wiki/Noumenalism#Kant.27s_usage; on Kant's view, the noumenon is opaque to direct experience and can only be derived from the phenomenon by a process of induction or abduction. Noumenalism is commonly cited as an argument against "naïve realism" – the belief that the world is pretty much the way we perceive it (cf. http://en.wikipedia.org/wiki/Naive_realism). The noumenalist argument against naïve realism goes something like this: "We can have no direct access to reality, therefore we can never be certain that our phenomenal experiences correspond to some noumenal reality. This being the case, to hold that the putative objects of our phenomenal experiences – material objects, physical events, concrete properties and relations etc. – correspond to the 'actual nature of phenomenal reality' is philosophically naïve."

We can indeed criticise the "pretheoretical categories" of entity with which we populate the "physical world", but this is a matter of investigating ontological commitment and the limits to our reduction of theories (or of our capacities to translate one theory into another). However, there is no reason to suppose that we are "hard-wired" to make any distinctions between phenomena save by the limits of our perceptual apparatus – thus, we cannot have optic perception of light at wavelengths greater or lower than the visible range. In some cases, our perceptual apparatus allows that one of our senses can experience phenomena that are beyond the range of another - we cannot have direct optic perception of light at wavelengths lower than the "visible range", though we can feel heat; we can have no direct auditory experience of very low-frequency sounds, though we can feel vibrations. But, other than these "perceptual capacities", we are "tabulae rasae" – there is not even the innate Cartesian capacity to make logical distinctions. This view is largely due to Locke (cf. http://en.wikipedia.org/wiki/John_Locke#The_self), though it has been largely modified by recent advances in pragmatic behaviouralist philosophies and by the evidence from the neurological and cognitive sciences.

As to Kant: Kantian noumenalism is a direct result of Cartesian dualism, and as such has had a widespread influence on the debate between monists and dualists. Generally speaking, an anti-dualist monism must show that the rejected domain (be it "the mental" or "the physical") is in some way an epiphenomenon.

1. REALITY

For my money, the problem is rather one of determining what it means for something to be "real". If our "criterion of reality" is causation (as with Davidson before 1985), then "what is physically real" will be "that which is the cause of a physical event"; if our criterion of reality is spatiotemporal localisation (as with Quine), then "what is physically real" is "that which occupies some region of spacetime". We can adopt the view that the contents of our phenomenal experience is "real" ("given directly in experience"), though we must also accept that such first-person experience is private and therefore illegitimate as the foundation of any public definition of reality. We can adopt a "heterophenomenological" approach in which we accept that a subject Susan is authoritative about what ***seems to be*** the case for her but by which we evaluate her statements of "what seems for her to be the case" by appeal to "what seems to us (and to others) to be the case" and to supporting evidence (Susan's more general behaviour, correlated regularities between the putative object of Susan's impressions and our more general beliefs concerning that "kind" of object etc. etc.).

We should bear in mind that the definition of "reality" is entirely informal and depends on metaphysical assumptions – and we should be most careful to distinguish between "reality" and "existence". Existence is a formal notion – "to be is to be the value of a variable", to quote Quine – and depends on quantifying existentially over the entities in some well-defined universe of discourse (our ontology depends on our choice of language). "Reality" is more a case of overt ontological commitment – thus, when we say something like "Othello's jealousy was the direct cause of Desdemona's death, but Iago's treachery was the indirect cause", we could claim that among the "furniture of the physical world", there really are "jealousies" and "treacheries"; our task here is to relate such entities to the more usual physical categories of "material object", "physical event", and "concrete process, disposition, or state of affairs".

2. LOCKE vs. KANT (round 1)

The idea that "we can have no direct access to noumenal reality" – in the following I'll call this notion "noumenalism"- is dependent on the notion that reality could be "other than we perceive it"; in the following, I'll argue against noumenalism as a product of the "Cartesian error" and suggest that saying that we can have no direct access to reality is not at all the same thing as saying that our apprehension of 'reality' is determined by our modes of access to a putative mind-independent world.

Noumenalism makes the Cartesian error of supposing that our sensory impressions could somehow "cheat" us in their reconstitution and representation of reality. Setting aside the "why" of the cheating, the error here is not in the notion of "reconstitution" – we do indeed seem to experience the world as 'unified', despite the different modes of access given by our sensory organs. The error is in the notion of "representation": the assumption that "reality" is *some thing* which can be represented ALSO presupposes that "reality" is represented TO *some thing*. We have a thing A that is represented to B and a thing B to which A is represented. If, against Descartes, we question the assumption of "B", the whole house of cards of noumenalism collapses. If there is no "B", there is no relation of representation; if there is no relation of representation, then "A" – the "noumenal reality to which we can have no direct access" – certainly can't be defined in terms of B having or not having access to A.

If I may use a metaphor : the stage of the Cartesian theatre might be brilliantly lit, but apart from the actors, the theatre is empty. Nothing and no-one is "watching" or "receiving" the contents of experience - indeed, the very idea of distinguishing "experience" and "the contents of experience" is already theory-laden.

We can, I think, argue that we have no need of a "spectator". When we distinguish between 'the contents of experience' and 'experience', we are postulating 'experience' as the province of a Cartesian subject and its 'contents' as "coming from without" – while it is true that I experience the taste and texture of the steak, what I am experiencing is NOT the taste and texture of the stake, but a 'false content' fed directly into my nerve system. This is not the way experience works, I think. My experience and the contents of my experience are not subject and object, but – if there is a distinction at all – at best subject and complement ("I am experiencing steakwise"). I'm not sure we can even make this distinction – there's no "fundamental experience" that can be separated from, for example "the experience of eating steak". If I might cite the classics, Cypher doesn't believe that the contents of his experience is false (otherwise he would have no reason for choosing the illusion). He simply accepts a metaphysical theory – that the causal web underlying his experiences is not the causal web of intuitive realism. For Cypher, the "myth of physical objects" no longer serves to explain the world of phenomenal experience – the myth of The Matrix is, within his narrative world, more compelling to reason. But his choice is still determined by a preference for the phenomenal reality of the experience of eating steak and drinking Château Margaux over the phenomenal reality of eating white goo and drinking raw alcohol.

My view is that, once we get rid of the Cartesian error, "the problem of noumenalism" in philosophical naturalism (PN) reduces to a simple contradiction implicit in PN's metaphysical assumptions. Now, PN postulates that there is a mind-independent reality. This postulates the weak assumption (WA) that things would happen whether or not they are 'known' to some mind (and hence the big problems posed by some interpretations of QM) – in other words, that the physical universe gets on with its business regardless of whatever we might say about it. Whatever it is about the apple that makes me see red is there even if it's midnight. Now, however tenable or not such views might be, they are NOT the strong assumption (SA) that "we cannot know reality".

"Mind-independence" is the tricky term. WA postulates that the world is there whether we think about it or not; it does NOT imply that we cannot have "knowledge about" the mind-independent world .

The error of SA is to understand "mind-independent" as "mind-inaccessible". The basic tenet of noumenalism is that Mind cannot have direct access to "noumenal reality". But if we remove the spectator from the Cartesian theatre of experience, there is no "misrepresentation" possible – "Mind" is not a spectator to whom Reality is being represented in a "narrative" which reunites the disparate modes of sensory impression. Mind is the narrative itself.

If Mind were the spectator of the narrative – the thing ***for which*** a unified image of reality had been reconstituted – then we would have four elements: "reality" (R), the "process or reconstitution" (P) by which sensory impressions of R are integrated; the "image of the world" (I) which is the result of 'P'; and the 'Cartesian spectator' (S) to whom 'I' represents 'R'.

We can, however, allow that 'R' is ***no more than*** 'mind-independent', and that 'P' is the process by sensory impressions of 'R' are integrated in experience. The "unified image of the world" 'I' is thus no more than a reification of 'P' – and this is the very banal observation that 'Mind' is a process, not an object. On THIS view, the "noumenalist objection" is just the very banal observation that we cannot have mind-independent experience of mind-independent reality.

All in all, noumenalism is based on the assumption that, although we can have no direct experience of it, there IS some reality which in some ways determines our phenomenal experiences (otherwise, we'd have nothing but phenomena, and this way Berkeley lies). Yet if we reduce "noumenal reality" to mind-independent reality, then it is evident that we cannot have mind-independent experience of that reality: experience is a 'mental process', and CANNOT be 'mind-independent'.

Of course, a lot of people would say "ah yes, but you can have an experience without thinking about it". Of course, but 'mental process' doesn't reduce to 'metacognitive process'. "Being aware" is not metacognition, but is rather a state of excitation fundamental to "having an experience" – if the 'experience' has no impact on your basic sensory and cognitive processes, then it's hard to say that you've "had the experience" (a high-level burst of gamma rays would be undetected by our immediate sensory apparatus – the 'experience' would be indirect, and given by the resultant destructive effects on bodily function).

That "reality" is mind-independent doesn't exclude that its is ALSO mind-dependent. Quite evidently, the notion of "reality" is itself mind-dependent: if there were no "minds", then the questions of whether "reality" is ordered, and "how" it is ordered, would never arise. Nor would the question of "order". All these questions are part of the "narrative" that we're acting out in the Cartesian theatre of Mind. But there are no spectators – just our fellow actors. While experience is 'private", Mind is not – it's an intersubjective domain which requires the interaction of human agents (our 'view of the world' is a matter of triangulation, not direct description. A term designates rigidly only when it can pick out one particular entity throughout all possible descriptions of time and space and for all possible speakers).

Most of all, Mind requires language if it is to serve as a means of triangulating from different perspectives of "the world"; however, this also requires that language is flexible enough to allow for a difference in perspective. While the categories into which we regiment phenomenal experience are linguistic and therefore general, certain linguistic resources (deictics, tense…) allow each speaker to interact with her linguistic community from a perspective that is perhaps local, but is nonetheless unique. "Mind" is itself a linguistic notion – indeed, we can ask whether the term 'linguistic notion' is not tautological – and, as such, cannot be reduced to the characteristics of an individual human being taken in isolation from any social or cultural context. Such a person would have no language, and therefore no equivalent to OUR concept 'Mind', which is irreversible tainted with the linguistic.

So, mind-dependence is not just a matter of "awareness", but also of language. We can push this as a partial redefinition of the hypothesis that "reality is mind-independent": "reality" would be *as it is* HOWEVER we might describe it; what matters is how well our descriptions of one part of reality integrate with our descriptions of other parts.

Now, this redefinition of "mind-independence" effectively brackets out 'awareness'. The problem is not whether our sensory impressions "reconstitute reality" faithfully or not, but whether the observation sentences we use to talk about those impressions are coherent with the observation sentences we use to talk about similar impressions at other times and in other places. Such similarities allow us to talk of 'phenomena', and to postulate relations between such 'phenomena' (to construct "special theories"); these "special theories" allow us to generalise from kinds of phenomena to "underlying regularities"; and the more "general theories" can be tested against experience as they *should* generate a certain class of observation sentences under certain controlled conditions (the view is restated in behavioural rather than mentalistic terms). Now, 'building up' from observation sentences to theories might serve a certain view of 'the abductive process', but we should ALSO bear in mind that the observation sentences are themselves the product of a given language and of the general assumptions that language makes about whatever 'part of the world' the observation sentences are supposed to be about (in this way, theories "face the tribunal of experience as a whole)".

We can go as far as to ask whether we should rather be postulating the language-independence of the world than its 'mind-independence' - or whether the two notions can even be distinguished.

***

I remarked above that, even if "reality" IS mind-independent, this doesn't exclude that its is ALSO mind-dependent. We could understand this as suggesting that

(1) mind-independent reality (MIR) and mind-dependent reality (MDR) are co-extensive;

(2) that MDR supervenes on MIR; or

(3) that MIR subvenes on MDR.

In its most banal form, (3) is no more than the recognition that the notion of MIR depends itself on language; if the subvenience relation were given ontological force, it would simply state that reality is mind-dependent.

(2) covers the familiar Humean supervenience of physical reductionism but could allow for less drastic or less top-down accounts (thus, if we want to keep a bottom-up ontology, we can employ such notions as 'emergence'; on the other hand, we can employ a top-down ontology and talk of theories "carving the world at the joints").

(1) is perhaps the notion that we should be discussing, rather than placing bets on a wrestling match between the straw man of "naïve scientific realism" and the self-defeating spectre of noumenalism.

3. LOCKE vs. KANT (round 2)

On reading the above, our good friend Nicole Pernat made the following remark :

"I agree that there is no self for which the world is re-presented. However, just as a thermometer gauges temperature while the mercury is not identical with the temperature, so our sensations & perceptions are not reality themselves"

I remarked to Nicole that when I was younger I was much taken by the "semiotic" account derived from CS Peirce: according to Peirce (and with apologies to the "real" experts!), a sign represents its object in three ways: either as an ICON - by some formal or topological resemblance (like a map, a graph or a photograph); as an INDEX – by some relation of "contiguity", and usually a causal relation (a footprint can indicate the presence of a person, a rash can indicate the presence of a virus…); or as a SYMBOL – by some convention or norm (language, of course, but also pictorial conventions, gestures – even silences!). Now, if we apply this simple model to the question in hand, we can see that ***the observable state of the mercury in the thermometer*** is in an indexical relation with the ***temperature of the mercury*** (its mean molecular momentum or whatever), and that THIS is in an indexical relation with ***the ambient temperature***. Each of the ***starred*** terms represents a "real" characteristic of the world, and each is linked to the other by a 'causelike' relation – the ***observable state*** is caused by the ***immediate temperature*** and the ***immediate temperature*** is determined by the ***ambient temperature***. In each case, we're talking about "real" states of the world (and remember that "the world" INCLUDES our perceptions) – what changes is the "epistemic system" by which reality is constructed (and I say "constructed" rather than "demonstrated" as *reality* is a linguistic notion, not some mind-independent characteristic of the world).

The observable state of the thermometer-system depends on our beliefs concerning the causal relation between the height of the mercury and the ambient temperature. We perceive the thermometer-system as being in a state which corresponds to, say, 8°C. There is a real state of the world which corresponds to our perception of the thermometer-system (let's call it "TH"). Unless we're hallucinating or misreading, the real state "TH" corresponds to a real state of the world which is the "temperature of the mercury as a system" ("TM"). The possibility of hallucination or misreading does indeed "come between" TH and TM (this is the entire premise of "The Matrix" series), but this more a question of interpreting the "real" content of a perceptual state.

How is this possible? Well, we've seen that there is a real INDEXICAL relation between our perception TH and the state of the (mind-independent) world TM and, given the physical and physiological characteristics of our perceptual systems, we take it that any ***perception*** has some cause – that is, that the perception is an index to "some" state - in Davidsonian terms, the phenomenal contents supposedly "supervenes" on some state of the perceptual system. The phenomenal contents is logically related to the "real perceptual state" (I'd say that the relation is one of identity), and the "real perceptual state" is the causal result of some "real stimulus". This is as much the case in hallucination as in "real" perception. In the Matrix, the phenomenal contents of the sleepers' experience corresponded logically to certain neurophysiological stimuli – the experience itself is "real" as it is a state which is the causal result of these stimuli, and the stimuli are "real" insofar as they are real physical events taking place in a definite region of spacetime. The sleepers are only mistaken in their naïve intuition that there is an ICONIC relation between the contents of their perceptual states and the stimuli – that when they see "a dog", the causal origin of that perception is indeed a mind-independent entity having certain physical, biological, and genetic characteristics. Whereas an index MUST have an object (it is caused by its object), an icon can be a pseudosign – just as one can create a "map" of an imaginary territory, or a "picture" of an entirely fictitious character. If you'll allow me the analogy, the "dog" seen by the Matrix sleeper is "no more than pigment on canvas" – there is "real pigment", but no "real dog". But whether the "dog" is "real dog" or "real pigment", it is still REAL.

The relation between the perceptual state "TH" and the state of the mercury-system "TM" is a relation between two real states, though WE must rely on circumstantial evidence to decide whether TM actually obtains (and this rejoins my comments on "states of affairs" and "possible worlds" on the philo group – we have to decide "which" world we're living in. I can develop further if you wish). If we take the "Matrix" example again, we have to decide whether we're living in a world where TH is caused by or correlates to the actual state of a real system TM, or whether we're living in a world where TH is caused by some Demon Machine stimulating our perceptual system. TH is not in doubt – though it is only accessible to "first-person experience". Now, while I can't appeal to MY first-person experience to found any "universal reality" of TH, our language does allow a certain "heterophenomenology" (to borrow Dennett's rather unlovely term http://en.wikipedia.org/wiki/Heterophenomenology): I can formulate an "observation sentence" of the kind "the thermometer gives a temperature of 8°C" to which any other observer can either assent or dissent – and should they assent to my description, I can hold-as-true that they are in an equivalent phenomenal state to my own. Of course (cf. the various "zombie" thought experiments), I have no *guarantee* that they are in such a state – my attribution is a matter of my having a Theory of Mind (http://en.wikipedia.org/wiki/Theory_of_mind) or adopting some kind of "intentional stance". Each person who assents to the observation sentence reinforces my justification in believing that a perceptual state equivalent to TH should hold for any observer, though it is of course impossible to PROVE that TH actually holds for any observer.

My argument that TH is "real" is perhaps founded on my direct and private access to my own perceptual states; while Cartesian phenomenology would disallow this as a statement of how things ***are*** to me, I can - to use Dennett's terms - be "authoritative" about how things ***seem*** to me. The context of my observation sentence is evidently "IT SEEMS TO ME THAT the thermometer gives a temperature of 8°C" – and in fact, I am making a statement about my perception, not about the world. But, as we appear as a species to have evolved similar responses to similar stimuli, and as my "understanding" of my perceptual state is largely dependent on the linguistic conventions which determine the formulation of observation sentences, there is a pragmatic precedent for holding that the statement of my perception corresponds to some state of affairs accessible to "other minds" – that is, that in the context of a ToM, the "reality" of TM is at least not *solipsistically* mind-dependent.

***

The "Matrix" (and similar "brain in a vat" thought experiments - http://en.wikipedia.org/wiki/Brain_in_a_vat) are predicated on the idea that TH – the perceptual state – "represents" TM (the state-of-the-world). As you'll recall from my criticism of the Cartesian theatre, the error is perhaps in the notion of "representation", for which there is not only an "of", but also a "to". We can, I believe, make a distinction between "representation" in the sense of "modelisation" and in the more Cartesian sense of "the act of presenting something to someone" (Piece made some comment about a sign "representing" its object in the same way that a diplomat "represents" his government, which would imply that our perceptions are "synecdoches" of their putative objects). In the following, I'll use the term "presentation" to cover the Cartesian notion.

If we take TH to be "structured" (that is, as seeming to be disposed in a certain way in a perceptual "space" and as having certain "parts" which bear a topological relation to each other), then it would "appear to us" rather like a picture. Now, if we hold to the Cartesian notion of "presentation", this *picture* is being "shown to" something (the cogito). If we return to the notion of an "iconic sign", the Cartesian theatre is here a cinema – the perceptual state constitutes a "photograph" or "film" of reality which is replayed live to the thinking subject. Thus we have the idea that our perceptions somehow "represent to us" the topological and mereological structure of "external reality".

We can criticise this notion on two levels. First, we can criticise its semiotic accuracy: as the putative cause of the perceptual state, the "state-of-the-world" is in an indexical rather than an iconic relation with the perceptual state, and we cannot therefore hold that the "real structure" of the perceptual object is accurately reflected in the structure of the perceptual state. Imagine, for instance, that reductionism to fundamental particles were true. We could at best hold that the "real structure" of the perceptual object ***causes*** the apparent structure of the perceptual state, and seek regularities and covariances between one and the other (though this would rather be a scientific investigation into quantum-level interactions between highly complex emergent systems, and in no way a phenomenological investigation). This is similar to correlating, say, a rash, a fever, and a cough with the presence of a certain virus – the virus in no way "resembles" the rash, the fever, or the cough: they are merely indices to its presence.

The second criticism is more directly philosophical, and depends on our rejection of the Cartesian notion of "representation". If we refuse the notion of the perceptual state as a sign "presenting" a real state-of-the-world TO some other thing (the cogito or whatever), there is no longer any need to postulate an iconic relation between our perceptual state and the state-of-the-world, as there is no distinction between the topological and mereological structure of the perception and its informational content: the structure does not "transmit" information – it "is" information. Speaking more phenomenologically, we cannot separate the "reality" of experience from its "contents": there is no distinction between the contents of a perceptual state and its putative Cartesian subject (the experience of "seeing a thermometer" cannot be prescinded from its grammatical subject – there is no "I" to which "seeing a thermometer" is presented, there is just "an experience of seeing some thing which is recognised as a thermometer".

Our phenomenal experiences would seem to be structured in both space and time – the keyboard is "nearer" to me than the monitor screen, and the sound of footsteps upstairs is "more recent" than the sound of a passing ambulance. They seem to have certain parts which bear certain relations to other parts. In our everyday interaction with the world, we don't even need to question whether the structure of our experience corresponds to the structure of the putative objects of experience. If we take "the world" as a domain of entities in causal relations, our experience is part of the world – we interact with the world as it is because we are PART of that world; the puzzle lies in HOW phenomenal experience is "part of the world", not in how phenomenal experience REPRESENTS the world.

We have no reason to ask whether our everyday phenomenal experience of the world "differs" from the world – it is rather "part" of the world. However, we can still investigate the KIND of causal relations obtaining between the putative "object of experience" and the experience. I see the monitor screen as a source of light, and it makes no "sense" to me to formulate my experience otherwise. It is most probably the case that there is a "causal" relation obtaining between the physical state of the screen and the physical state of my perceptual apparatus, and that this causal relation could be described in terms of elementary-level interactions between complex systems. But it's meaningless to seek ***parts*** of "my experience of the screen" in particular fundamental interactions – the experience is an emergent phenomenon, and its "parts" are determined by relations obtaining at the emergent level.

The Master of Königsberg famously differentiated between what is given in perception by the senses (the "phenomenon") and the thing-in-itself, the Ding an sich (the "noumenon") – cf. http://en.wikipedia.org/wiki/Noumenalism#Kant.27s_usage; on Kant's view, the noumenon is opaque to direct experience and can only be derived from the phenomenon by a process of induction or abduction. Noumenalism is commonly cited as an argument against "naïve realism" – the belief that the world is pretty much the way we perceive it (cf. http://en.wikipedia.org/wiki/Naive_realism). The noumenalist argument against naïve realism goes something like this: "We can have no direct access to reality, therefore we can never be certain that our phenomenal experiences correspond to some noumenal reality. This being the case, to hold that the putative objects of our phenomenal experiences – material objects, physical events, concrete properties and relations etc. – correspond to the 'actual nature of phenomenal reality' is philosophically naïve."

We can indeed criticise the "pretheoretical categories" of entity with which we populate the "physical world", but this is a matter of investigating ontological commitment and the limits to our reduction of theories (or of our capacities to translate one theory into another). However, there is no reason to suppose that we are "hard-wired" to make any distinctions between phenomena save by the limits of our perceptual apparatus – thus, we cannot have optic perception of light at wavelengths greater or lower than the visible range. In some cases, our perceptual apparatus allows that one of our senses can experience phenomena that are beyond the range of another - we cannot have direct optic perception of light at wavelengths lower than the "visible range", though we can feel heat; we can have no direct auditory experience of very low-frequency sounds, though we can feel vibrations. But, other than these "perceptual capacities", we are "tabulae rasae" – there is not even the innate Cartesian capacity to make logical distinctions. This view is largely due to Locke (cf. http://en.wikipedia.org/wiki/John_Locke#The_self), though it has been largely modified by recent advances in pragmatic behaviouralist philosophies and by the evidence from the neurological and cognitive sciences.

As to Kant: Kantian noumenalism is a direct result of Cartesian dualism, and as such has had a widespread influence on the debate between monists and dualists. Generally speaking, an anti-dualist monism must show that the rejected domain (be it "the mental" or "the physical") is in some way an epiphenomenon.

1. REALITY

For my money, the problem is rather one of determining what it means for something to be "real". If our "criterion of reality" is causation (as with Davidson before 1985), then "what is physically real" will be "that which is the cause of a physical event"; if our criterion of reality is spatiotemporal localisation (as with Quine), then "what is physically real" is "that which occupies some region of spacetime". We can adopt the view that the contents of our phenomenal experience is "real" ("given directly in experience"), though we must also accept that such first-person experience is private and therefore illegitimate as the foundation of any public definition of reality. We can adopt a "heterophenomenological" approach in which we accept that a subject Susan is authoritative about what ***seems to be*** the case for her but by which we evaluate her statements of "what seems for her to be the case" by appeal to "what seems to us (and to others) to be the case" and to supporting evidence (Susan's more general behaviour, correlated regularities between the putative object of Susan's impressions and our more general beliefs concerning that "kind" of object etc. etc.).

We should bear in mind that the definition of "reality" is entirely informal and depends on metaphysical assumptions – and we should be most careful to distinguish between "reality" and "existence". Existence is a formal notion – "to be is to be the value of a variable", to quote Quine – and depends on quantifying existentially over the entities in some well-defined universe of discourse (our ontology depends on our choice of language). "Reality" is more a case of overt ontological commitment – thus, when we say something like "Othello's jealousy was the direct cause of Desdemona's death, but Iago's treachery was the indirect cause", we could claim that among the "furniture of the physical world", there really are "jealousies" and "treacheries"; our task here is to relate such entities to the more usual physical categories of "material object", "physical event", and "concrete process, disposition, or state of affairs".

2. LOCKE vs. KANT (round 1)

The idea that "we can have no direct access to noumenal reality" – in the following I'll call this notion "noumenalism"- is dependent on the notion that reality could be "other than we perceive it"; in the following, I'll argue against noumenalism as a product of the "Cartesian error" and suggest that saying that we can have no direct access to reality is not at all the same thing as saying that our apprehension of 'reality' is determined by our modes of access to a putative mind-independent world.

Noumenalism makes the Cartesian error of supposing that our sensory impressions could somehow "cheat" us in their reconstitution and representation of reality. Setting aside the "why" of the cheating, the error here is not in the notion of "reconstitution" – we do indeed seem to experience the world as 'unified', despite the different modes of access given by our sensory organs. The error is in the notion of "representation": the assumption that "reality" is *some thing* which can be represented ALSO presupposes that "reality" is represented TO *some thing*. We have a thing A that is represented to B and a thing B to which A is represented. If, against Descartes, we question the assumption of "B", the whole house of cards of noumenalism collapses. If there is no "B", there is no relation of representation; if there is no relation of representation, then "A" – the "noumenal reality to which we can have no direct access" – certainly can't be defined in terms of B having or not having access to A.

If I may use a metaphor : the stage of the Cartesian theatre might be brilliantly lit, but apart from the actors, the theatre is empty. Nothing and no-one is "watching" or "receiving" the contents of experience - indeed, the very idea of distinguishing "experience" and "the contents of experience" is already theory-laden.

We can, I think, argue that we have no need of a "spectator". When we distinguish between 'the contents of experience' and 'experience', we are postulating 'experience' as the province of a Cartesian subject and its 'contents' as "coming from without" – while it is true that I experience the taste and texture of the steak, what I am experiencing is NOT the taste and texture of the stake, but a 'false content' fed directly into my nerve system. This is not the way experience works, I think. My experience and the contents of my experience are not subject and object, but – if there is a distinction at all – at best subject and complement ("I am experiencing steakwise"). I'm not sure we can even make this distinction – there's no "fundamental experience" that can be separated from, for example "the experience of eating steak". If I might cite the classics, Cypher doesn't believe that the contents of his experience is false (otherwise he would have no reason for choosing the illusion). He simply accepts a metaphysical theory – that the causal web underlying his experiences is not the causal web of intuitive realism. For Cypher, the "myth of physical objects" no longer serves to explain the world of phenomenal experience – the myth of The Matrix is, within his narrative world, more compelling to reason. But his choice is still determined by a preference for the phenomenal reality of the experience of eating steak and drinking Château Margaux over the phenomenal reality of eating white goo and drinking raw alcohol.

My view is that, once we get rid of the Cartesian error, "the problem of noumenalism" in philosophical naturalism (PN) reduces to a simple contradiction implicit in PN's metaphysical assumptions. Now, PN postulates that there is a mind-independent reality. This postulates the weak assumption (WA) that things would happen whether or not they are 'known' to some mind (and hence the big problems posed by some interpretations of QM) – in other words, that the physical universe gets on with its business regardless of whatever we might say about it. Whatever it is about the apple that makes me see red is there even if it's midnight. Now, however tenable or not such views might be, they are NOT the strong assumption (SA) that "we cannot know reality".

"Mind-independence" is the tricky term. WA postulates that the world is there whether we think about it or not; it does NOT imply that we cannot have "knowledge about" the mind-independent world .

The error of SA is to understand "mind-independent" as "mind-inaccessible". The basic tenet of noumenalism is that Mind cannot have direct access to "noumenal reality". But if we remove the spectator from the Cartesian theatre of experience, there is no "misrepresentation" possible – "Mind" is not a spectator to whom Reality is being represented in a "narrative" which reunites the disparate modes of sensory impression. Mind is the narrative itself.

If Mind were the spectator of the narrative – the thing ***for which*** a unified image of reality had been reconstituted – then we would have four elements: "reality" (R), the "process or reconstitution" (P) by which sensory impressions of R are integrated; the "image of the world" (I) which is the result of 'P'; and the 'Cartesian spectator' (S) to whom 'I' represents 'R'.

We can, however, allow that 'R' is ***no more than*** 'mind-independent', and that 'P' is the process by sensory impressions of 'R' are integrated in experience. The "unified image of the world" 'I' is thus no more than a reification of 'P' – and this is the very banal observation that 'Mind' is a process, not an object. On THIS view, the "noumenalist objection" is just the very banal observation that we cannot have mind-independent experience of mind-independent reality.

All in all, noumenalism is based on the assumption that, although we can have no direct experience of it, there IS some reality which in some ways determines our phenomenal experiences (otherwise, we'd have nothing but phenomena, and this way Berkeley lies). Yet if we reduce "noumenal reality" to mind-independent reality, then it is evident that we cannot have mind-independent experience of that reality: experience is a 'mental process', and CANNOT be 'mind-independent'.

Of course, a lot of people would say "ah yes, but you can have an experience without thinking about it". Of course, but 'mental process' doesn't reduce to 'metacognitive process'. "Being aware" is not metacognition, but is rather a state of excitation fundamental to "having an experience" – if the 'experience' has no impact on your basic sensory and cognitive processes, then it's hard to say that you've "had the experience" (a high-level burst of gamma rays would be undetected by our immediate sensory apparatus – the 'experience' would be indirect, and given by the resultant destructive effects on bodily function).

That "reality" is mind-independent doesn't exclude that its is ALSO mind-dependent. Quite evidently, the notion of "reality" is itself mind-dependent: if there were no "minds", then the questions of whether "reality" is ordered, and "how" it is ordered, would never arise. Nor would the question of "order". All these questions are part of the "narrative" that we're acting out in the Cartesian theatre of Mind. But there are no spectators – just our fellow actors. While experience is 'private", Mind is not – it's an intersubjective domain which requires the interaction of human agents (our 'view of the world' is a matter of triangulation, not direct description. A term designates rigidly only when it can pick out one particular entity throughout all possible descriptions of time and space and for all possible speakers).

Most of all, Mind requires language if it is to serve as a means of triangulating from different perspectives of "the world"; however, this also requires that language is flexible enough to allow for a difference in perspective. While the categories into which we regiment phenomenal experience are linguistic and therefore general, certain linguistic resources (deictics, tense…) allow each speaker to interact with her linguistic community from a perspective that is perhaps local, but is nonetheless unique. "Mind" is itself a linguistic notion – indeed, we can ask whether the term 'linguistic notion' is not tautological – and, as such, cannot be reduced to the characteristics of an individual human being taken in isolation from any social or cultural context. Such a person would have no language, and therefore no equivalent to OUR concept 'Mind', which is irreversible tainted with the linguistic.

So, mind-dependence is not just a matter of "awareness", but also of language. We can push this as a partial redefinition of the hypothesis that "reality is mind-independent": "reality" would be *as it is* HOWEVER we might describe it; what matters is how well our descriptions of one part of reality integrate with our descriptions of other parts.

Now, this redefinition of "mind-independence" effectively brackets out 'awareness'. The problem is not whether our sensory impressions "reconstitute reality" faithfully or not, but whether the observation sentences we use to talk about those impressions are coherent with the observation sentences we use to talk about similar impressions at other times and in other places. Such similarities allow us to talk of 'phenomena', and to postulate relations between such 'phenomena' (to construct "special theories"); these "special theories" allow us to generalise from kinds of phenomena to "underlying regularities"; and the more "general theories" can be tested against experience as they *should* generate a certain class of observation sentences under certain controlled conditions (the view is restated in behavioural rather than mentalistic terms). Now, 'building up' from observation sentences to theories might serve a certain view of 'the abductive process', but we should ALSO bear in mind that the observation sentences are themselves the product of a given language and of the general assumptions that language makes about whatever 'part of the world' the observation sentences are supposed to be about (in this way, theories "face the tribunal of experience as a whole)".

We can go as far as to ask whether we should rather be postulating the language-independence of the world than its 'mind-independence' - or whether the two notions can even be distinguished.

***

I remarked above that, even if "reality" IS mind-independent, this doesn't exclude that its is ALSO mind-dependent. We could understand this as suggesting that

(1) mind-independent reality (MIR) and mind-dependent reality (MDR) are co-extensive;

(2) that MDR supervenes on MIR; or

(3) that MIR subvenes on MDR.

In its most banal form, (3) is no more than the recognition that the notion of MIR depends itself on language; if the subvenience relation were given ontological force, it would simply state that reality is mind-dependent.

(2) covers the familiar Humean supervenience of physical reductionism but could allow for less drastic or less top-down accounts (thus, if we want to keep a bottom-up ontology, we can employ such notions as 'emergence'; on the other hand, we can employ a top-down ontology and talk of theories "carving the world at the joints").

(1) is perhaps the notion that we should be discussing, rather than placing bets on a wrestling match between the straw man of "naïve scientific realism" and the self-defeating spectre of noumenalism.

3. LOCKE vs. KANT (round 2)

On reading the above, our good friend Nicole Pernat made the following remark :

"I agree that there is no self for which the world is re-presented. However, just as a thermometer gauges temperature while the mercury is not identical with the temperature, so our sensations & perceptions are not reality themselves"

I remarked to Nicole that when I was younger I was much taken by the "semiotic" account derived from CS Peirce: according to Peirce (and with apologies to the "real" experts!), a sign represents its object in three ways: either as an ICON - by some formal or topological resemblance (like a map, a graph or a photograph); as an INDEX – by some relation of "contiguity", and usually a causal relation (a footprint can indicate the presence of a person, a rash can indicate the presence of a virus…); or as a SYMBOL – by some convention or norm (language, of course, but also pictorial conventions, gestures – even silences!). Now, if we apply this simple model to the question in hand, we can see that ***the observable state of the mercury in the thermometer*** is in an indexical relation with the ***temperature of the mercury*** (its mean molecular momentum or whatever), and that THIS is in an indexical relation with ***the ambient temperature***. Each of the ***starred*** terms represents a "real" characteristic of the world, and each is linked to the other by a 'causelike' relation – the ***observable state*** is caused by the ***immediate temperature*** and the ***immediate temperature*** is determined by the ***ambient temperature***. In each case, we're talking about "real" states of the world (and remember that "the world" INCLUDES our perceptions) – what changes is the "epistemic system" by which reality is constructed (and I say "constructed" rather than "demonstrated" as *reality* is a linguistic notion, not some mind-independent characteristic of the world).

The observable state of the thermometer-system depends on our beliefs concerning the causal relation between the height of the mercury and the ambient temperature. We perceive the thermometer-system as being in a state which corresponds to, say, 8°C. There is a real state of the world which corresponds to our perception of the thermometer-system (let's call it "TH"). Unless we're hallucinating or misreading, the real state "TH" corresponds to a real state of the world which is the "temperature of the mercury as a system" ("TM"). The possibility of hallucination or misreading does indeed "come between" TH and TM (this is the entire premise of "The Matrix" series), but this more a question of interpreting the "real" content of a perceptual state.

How is this possible? Well, we've seen that there is a real INDEXICAL relation between our perception TH and the state of the (mind-independent) world TM and, given the physical and physiological characteristics of our perceptual systems, we take it that any ***perception*** has some cause – that is, that the perception is an index to "some" state - in Davidsonian terms, the phenomenal contents supposedly "supervenes" on some state of the perceptual system. The phenomenal contents is logically related to the "real perceptual state" (I'd say that the relation is one of identity), and the "real perceptual state" is the causal result of some "real stimulus". This is as much the case in hallucination as in "real" perception. In the Matrix, the phenomenal contents of the sleepers' experience corresponded logically to certain neurophysiological stimuli – the experience itself is "real" as it is a state which is the causal result of these stimuli, and the stimuli are "real" insofar as they are real physical events taking place in a definite region of spacetime. The sleepers are only mistaken in their naïve intuition that there is an ICONIC relation between the contents of their perceptual states and the stimuli – that when they see "a dog", the causal origin of that perception is indeed a mind-independent entity having certain physical, biological, and genetic characteristics. Whereas an index MUST have an object (it is caused by its object), an icon can be a pseudosign – just as one can create a "map" of an imaginary territory, or a "picture" of an entirely fictitious character. If you'll allow me the analogy, the "dog" seen by the Matrix sleeper is "no more than pigment on canvas" – there is "real pigment", but no "real dog". But whether the "dog" is "real dog" or "real pigment", it is still REAL.

The relation between the perceptual state "TH" and the state of the mercury-system "TM" is a relation between two real states, though WE must rely on circumstantial evidence to decide whether TM actually obtains (and this rejoins my comments on "states of affairs" and "possible worlds" on the philo group – we have to decide "which" world we're living in. I can develop further if you wish). If we take the "Matrix" example again, we have to decide whether we're living in a world where TH is caused by or correlates to the actual state of a real system TM, or whether we're living in a world where TH is caused by some Demon Machine stimulating our perceptual system. TH is not in doubt – though it is only accessible to "first-person experience". Now, while I can't appeal to MY first-person experience to found any "universal reality" of TH, our language does allow a certain "heterophenomenology" (to borrow Dennett's rather unlovely term http://en.wikipedia.org/wiki/Heterophenomenology): I can formulate an "observation sentence" of the kind "the thermometer gives a temperature of 8°C" to which any other observer can either assent or dissent – and should they assent to my description, I can hold-as-true that they are in an equivalent phenomenal state to my own. Of course (cf. the various "zombie" thought experiments), I have no *guarantee* that they are in such a state – my attribution is a matter of my having a Theory of Mind (http://en.wikipedia.org/wiki/Theory_of_mind) or adopting some kind of "intentional stance". Each person who assents to the observation sentence reinforces my justification in believing that a perceptual state equivalent to TH should hold for any observer, though it is of course impossible to PROVE that TH actually holds for any observer.

My argument that TH is "real" is perhaps founded on my direct and private access to my own perceptual states; while Cartesian phenomenology would disallow this as a statement of how things ***are*** to me, I can - to use Dennett's terms - be "authoritative" about how things ***seem*** to me. The context of my observation sentence is evidently "IT SEEMS TO ME THAT the thermometer gives a temperature of 8°C" – and in fact, I am making a statement about my perception, not about the world. But, as we appear as a species to have evolved similar responses to similar stimuli, and as my "understanding" of my perceptual state is largely dependent on the linguistic conventions which determine the formulation of observation sentences, there is a pragmatic precedent for holding that the statement of my perception corresponds to some state of affairs accessible to "other minds" – that is, that in the context of a ToM, the "reality" of TM is at least not *solipsistically* mind-dependent.

***

The "Matrix" (and similar "brain in a vat" thought experiments - http://en.wikipedia.org/wiki/Brain_in_a_vat) are predicated on the idea that TH – the perceptual state – "represents" TM (the state-of-the-world). As you'll recall from my criticism of the Cartesian theatre, the error is perhaps in the notion of "representation", for which there is not only an "of", but also a "to". We can, I believe, make a distinction between "representation" in the sense of "modelisation" and in the more Cartesian sense of "the act of presenting something to someone" (Piece made some comment about a sign "representing" its object in the same way that a diplomat "represents" his government, which would imply that our perceptions are "synecdoches" of their putative objects). In the following, I'll use the term "presentation" to cover the Cartesian notion.

If we take TH to be "structured" (that is, as seeming to be disposed in a certain way in a perceptual "space" and as having certain "parts" which bear a topological relation to each other), then it would "appear to us" rather like a picture. Now, if we hold to the Cartesian notion of "presentation", this *picture* is being "shown to" something (the cogito). If we return to the notion of an "iconic sign", the Cartesian theatre is here a cinema – the perceptual state constitutes a "photograph" or "film" of reality which is replayed live to the thinking subject. Thus we have the idea that our perceptions somehow "represent to us" the topological and mereological structure of "external reality".

We can criticise this notion on two levels. First, we can criticise its semiotic accuracy: as the putative cause of the perceptual state, the "state-of-the-world" is in an indexical rather than an iconic relation with the perceptual state, and we cannot therefore hold that the "real structure" of the perceptual object is accurately reflected in the structure of the perceptual state. Imagine, for instance, that reductionism to fundamental particles were true. We could at best hold that the "real structure" of the perceptual object ***causes*** the apparent structure of the perceptual state, and seek regularities and covariances between one and the other (though this would rather be a scientific investigation into quantum-level interactions between highly complex emergent systems, and in no way a phenomenological investigation). This is similar to correlating, say, a rash, a fever, and a cough with the presence of a certain virus – the virus in no way "resembles" the rash, the fever, or the cough: they are merely indices to its presence.

The second criticism is more directly philosophical, and depends on our rejection of the Cartesian notion of "representation". If we refuse the notion of the perceptual state as a sign "presenting" a real state-of-the-world TO some other thing (the cogito or whatever), there is no longer any need to postulate an iconic relation between our perceptual state and the state-of-the-world, as there is no distinction between the topological and mereological structure of the perception and its informational content: the structure does not "transmit" information – it "is" information. Speaking more phenomenologically, we cannot separate the "reality" of experience from its "contents": there is no distinction between the contents of a perceptual state and its putative Cartesian subject (the experience of "seeing a thermometer" cannot be prescinded from its grammatical subject – there is no "I" to which "seeing a thermometer" is presented, there is just "an experience of seeing some thing which is recognised as a thermometer".

Our phenomenal experiences would seem to be structured in both space and time – the keyboard is "nearer" to me than the monitor screen, and the sound of footsteps upstairs is "more recent" than the sound of a passing ambulance. They seem to have certain parts which bear certain relations to other parts. In our everyday interaction with the world, we don't even need to question whether the structure of our experience corresponds to the structure of the putative objects of experience. If we take "the world" as a domain of entities in causal relations, our experience is part of the world – we interact with the world as it is because we are PART of that world; the puzzle lies in HOW phenomenal experience is "part of the world", not in how phenomenal experience REPRESENTS the world.

We have no reason to ask whether our everyday phenomenal experience of the world "differs" from the world – it is rather "part" of the world. However, we can still investigate the KIND of causal relations obtaining between the putative "object of experience" and the experience. I see the monitor screen as a source of light, and it makes no "sense" to me to formulate my experience otherwise. It is most probably the case that there is a "causal" relation obtaining between the physical state of the screen and the physical state of my perceptual apparatus, and that this causal relation could be described in terms of elementary-level interactions between complex systems. But it's meaningless to seek ***parts*** of "my experience of the screen" in particular fundamental interactions – the experience is an emergent phenomenon, and its "parts" are determined by relations obtaining at the emergent level.

This is a very long message indeed, and I apologise in advance. But perhaps worth it.

The 'scientific' data concerning the specious present allows some interesting speculation; to follow and develop on our last exchange, we can look at this - in part, at least - as some kind of 'informed metascientific reflection'…

*Acts of presentation*

IF acts of presentation are taken as the basis for establishing the specious present, we can – following Gibson and Pooley's (2006) comments on the 'Stein present' - calculate its 'extent' in spacetime. According to the data you give, acts of presentation last from 200ms to 3000ms, with an average duration of approximately 700ms. By a simple-enough calculation, this allows us to describe the specious present as a four-dimensional discus shaped region with a spatial radius of from 60 000km – 900 000km and a temporal extent of 0.2s to 3s, with an average radius of 210 000 km for a temporal extent of 0.7s. This is of course the maximum spatial extent for the intervals under consideration; the 'real' extent would depend on local conditions; nonetheless, it would still allow for a vast number of events that might occur 'within' the subject's specious present – and with which he can 'interact' (and we can compare this with the extremely limited number of events with which the subject can interact if we retain the classical, Augustinian "instantaneous present").

We should also bear in mind that the specious present thus defined is a very different hypothesis from a specious present based on a 'timelet' in the sense given in the Bell paper. While relativistic effects would be negligible over the distances implied by a timelet, they would certainly be observable at the kinds of distance I give above - for observers in different inertial frames, events which for the subject take place *within* his specious present could therefore seem to take place just before or just after it. Furthermore, while each individual occupies their particular specious present, the specious present of any one doesn't coincide exactly with that of any other. Both these points militate against the 'absolute now' required by classical presentism, and would seem to lend support for the eternalist view.

The 'perceived order of events' within the subject's specious present would also seem to militate against the Augustinian view of the present, and more particularly against the classical accounts of the order of events in time (and this, I would surmise, is the point that leads you to a partial rejection of the classic A-series/B-series opposition). Of course - and as you'd certainly be the first to agree - once we enter the realm of 'phenomenal experience' and 'psychological representation', we can no longer take 'physics' as our guide; the perception of events is dependent on numerous emergent physiological factors, to say nothing of the phenomenological component. All the same, when we consider the 'inner organisation' of events you cite, we can make some interesting speculations. To recap, this inner organisation corresponds largely to "(a) the distinction between focus and periphery, (b) the presence of internal laws of organization, and (c) the elaboration of their content in subsequent stages".

(a) would imply that the 'specious present' is not an undifferentiated region of spacetime. Let's – for the sake of argument – imagine that the 'focus' of attention concerns a region corresponding to the shorter end of the interval range (we can call this "F"), while its 'periphery' coincides with a region corresponding to the longer end of the range (we can call this "P").

Now, there is evidently a region of P that corresponds to F's immediate future. Following (b) we can allow that the perceived 'internal temporal sequence' of events within P might not correspond to the physical order of events; if we also allow that *all* events occurring within P are *at least* accessible from F, this would suggest the very interesting conclusion that our 'subjective present' covers events which are slightly in the future of the 'focus of our immediate attention'.

***

A LONG BUT FRUITFUL DIVERSION

We can push speculation even further if we tie in the timelet as some kind of 'minimal spatiotemporally-oriented unit' (and I would stress that this is indeed taking speculation to perhaps unacceptable limits):

Let's imagine a timelet as being an infinitesimally short but irreducible 'interval' of around the Planck time - around 5.4×10−44 s. [Already, we should be conscious of a certain bias inherent in the choice, as the Planck time is a theoretical limit set by the mainstream view in contemporary physics; some theories and certain evidence would argue against the "Planck limit" as a *real* limit in the physical world. This is not really pertinent to Bell's arguments, as – unless my weak maths is letting me down - they hold at orders of magnitude significantly lower than the Planck limit; and furthermore, the Planck limit represents no more than a convenient peg on which we can hang a more metaphysical hypothesis.]

Setting aside this proviso, such timelets would be necessarily theoretical - that is, they are elements of a 'representation', and not of a 'reality'. This is because timelets are hypothetical one-dimensional entities corresponding to regions that are limited in four dimensions (like 'instants', they are hyperplanes of simultaneity); however, and given our theoretical understanding, it is extremely unlikely that we could make any meaningful distinctions between spatial and temporal dimensions for any 'sub-regions' *at or below* the Planck limit.

What *is* of theoretical importance – and perhaps of metaphysical interest – is that the Planck size represents an apparent limit to the four-dimensional model of spacetime. [Once again, we should add a proviso: this is of real import only if we consider certain mainstream models of 'quantum gravity' – in classical relativity, it is quite evidently NOT a limit to the mathematical modelling of 4-D spacetime; furthermore, on the theories evoked above – string theory is representative – quantum effects are not limited to the Planck scale].

Let us, nonetheless, draw the *philosophical* lesson that the Planck size represents a certain limit to a certain way of *representing* space and time. Here the notion of representation *is* important, as we have reached the limits of how we can correlate our empirical description of 'space and time' with our empirical description of 'matter' (the 'contents' of space and time). Both relativity and QM are theories built primarily on empirical evidence; historically, they represent the bouleversement of our naive belief that local conditions held universally both for the very large and for the very small (in this, they represent part of the massive epistemological revision (see NOTE below) which our worldview has been undergoing since Galileo (and perhaps Ockham and Friar Bacon ?).

In a very real sense, the 'grains' or the 'quantum foam' which our more classical theories predict represent the limit of a 'certain way of seeing the world'; and this 'certain way' is the view which promotes empiricism – the theory that knowledge of the world comes ultimately from direct experience, which is itself a question of the correlation of sensory impressions with 'webs of belief' concerning the relation of such impressions to certain kinds of phenomena. In less technical terms, it represents a limit to our *intuitions* about the world.

What are these *intuitions* about the world? That it has three dimensions of space, that it has a temporal dimension which might well be a fourth dimension of spacetime, that it contains 'things' which have 'properties' and undergo 'change', and that these 'things' can enter into relation with each other through 'occurrences' which bring about 'change'… these are the fundamental intuitions on which we have constructed our 'representation' of the *physical world*. The more scientifically-minded (Carl Hoefer, in his Stanford entry on "Causal determinism", comes to mind) will point out that our entire philosophy is polluted with such notions; nonetheless, it is such notions that metaphysical philosophy has traditionally sought to elucidate.

More importantly, the breakdown of observational empiricism would also seem to signal the failure of the neo-Quinean programme I've been defending, which draws much of its metaphysics from the descriptions of the world given by empirical science. Nonetheless, anyone who would draw this conclusion makes the mistake of forgetting that philosophy is a *linguistic* discipline. The neo-Quinean thesis is that BOTH our sense impressions and our language allow us "access to the world"; for if our sense impressions were not linked through 'observation sentences' to our general beliefs about the world and its contents, they would be meaningless sensations. Likewise, if our language did not have "to face the tribunal of experience", we would have no sure refuge but solipsism. These are purely philosophical concerns – given 'sense impressions' on the one hand, and 'language as the expression of a web of belief" on the other, we can derive 'phenomena' whenever certain *kinds* of sense impression are followed by certain, other, *kinds* of sense impression: indeed, Charles Peirce built an entire metaphysic of the sign on similar notions. The breakdown of the model of the world derived from the correlation of our sense impressions (however enhanced) and our language (however philosophically refined) is not so much a breakdown of our powers of description (our mathematics, and the physical theories derived from it, are still coherent), but rather a breakdown of our ability to draw analogies with our unenhanced, unrefined experience as human beings. We can grasp the idea of atoms being a 'little bit like little solar systems', of the solar system being 'a little bit like whirling a lot of stones around your head'; we can go further, and grasp – with less intuitive certainty, but still without too great an affront to our powers of analogy, the idea that particle are 'smeared-out' over areas of space and time that are more like probabilities than locations, and that massive bodies follow geodesics in curved spacetime. But surely, unless the universe was constructed either for or by the human mind, there is a limit at which new 'knowledge' can only be integrated by analogy with notions that are themselves at the limit of what our 'intuition' can grasp (this notion parallels, of course, the limit implied by the Planck scale in classical physical theory).

Quine suggested that we adopt or integrate the scientific account not from naïve scientific realism, but in order to clear up certain purely philosophical problems (the traditional problems of "First Philosophy") – more recently, Ted Sider ("Four-dimensionalism", 2001) gives similar justification for accepting the 'counter-intuitive' hypothesis that entities persist through an ontology-undifferentiated four-dimensional spacetime. Our concern as philosophers is not to arbitrate on which particular order of magnitude represents the 'actual frontier of reality', but rather to account for our intuitions concerning objects, properties, change, time, space, events and the like.

Two of the constants from which the Planck limit is derived – c and G - concern notions ('light' and 'gravity') that, albeit entirely refined of their everyday sense, are derived from fundamental and initially-unenhanced empirical observation; h-bar is more distantly derived from reflections on energy and work. But, however refined they might be, they are distantly descended from elements we first detect in our reflections on our phenomenal experience. At certain orders of magnitude, and whichever account (QFT, M-theory, "Many Worlds"…) best approximates 'the nature of reality', we can no longer find anything that corresponds to our 'intuitive view of reality'.

This rather long diversion allows us to establish a philosophical position: whatever the "actual nature of reality" at and below the Planck limit, and whatever the "actual effects" of quantum occurrences at and above the Planck level, we can provide a reasonable philosophical argument for considering *a certain level* of 'reality' as representing a limit for any metaphysical analysis of our 'everyday talk' about objects, time and the like – as these notions have no apparent correlates beyond such a level. This notion is addressed "philosophically" by Bell's arguments: if we can describe mathematically the minimum interval in which spacetime has 'orientation' while not yet exhibiting curvature, then we have described the conceptually-minimal notion we can have about spacetime (a classical singularity is, of course, a point at which our notions 'break down').

***

Once we allow that, ultimately, it might not be able to give us nice, clear-cut boxes into which we can sort objects, times, locations and the like, ontology is a flexible discipline. While we can't be sure what's going on 'down there', we can see what's going on 'up here' – and, with enhancement, to the upper limits of the 'visible' universe. Our ontology of planets, stars, and satellites is as certain as our ontology of rocks, oceans, and volcanoes; our ontology of galaxies is as well founded on our ontology of stars as our ontology of gases is founded on our ontology of molecules. Human beings, nuclear explosions, and (perhaps) the colour blue inhabit the 'same' world of space and time; and by extension, so do biological cells, sub-atomic reactions and (possibly) sense impressions. [The qualification in both sets of examples denotes the demarcation between the scientific and the philosophical investigation of 'our' world].

Language carves reality, whether that 'reality' is a hypostasis of language itself or some independent regularity underlying our phenomenal experience. We can use our language of 'everyday things', with a few additions from general scientific culture, to carve the world to our guise, basing – either implicitly or explicitly – our statements on conditions obtaining in this or that region of spacetime. "There's a dog in the garden" implicitly defines a certain region of space (I take it my interlocutor knows to which particular garden I'm referring) and a certain interval of time (around the time of speaking); it also reports on conditions obtaining in a certain sub-region of that space within that interval; we can perhaps avoid going as far as Quine in saying that the content of that region 'dogs', but still retain the general idea: "a dog occupies a certain sub-region of that region of spacetime which is this particular garden" [the objection that there might be more than one dog is a straw man]. It follows from my beliefs about dogs that I would affirm (if asked) that within this same region there is a mass of various biological tissue etc. etc.; it follows from my views as a philosopher that I would postulate that the region contained a stage or part of a perduring four-dimensional entity. We can, as I remarked, carve spacetime to our guise; the limitation is generally that what we carve make some kind of intuitive sense (an entity which consists of my nose, the Eiffel Tower in 1903, and the assassination of Julius Caesar is entirely possible but serves no intuitively-acceptable end, save in philosophical discourse). It would seem that, down to a certain limit, and however much we might adapt or modify it, this criterion of "intuitive sense" serves in the justification of our philosophical positions.

TO RETURN TO "TIMELETS"

If we follow this line of reasoning, we can perhaps consider "timelets" to be representations or models of the fundamental elements of our intuitive understanding of time. I remarked above that "timelets" are hypothetical one-dimensional entities corresponding to regions that are limited in four dimensions; this being the case, we should rather use a term which implies both their spatial and their temporal extent – and here we arrive by an independent route to Roberto's "chronotopoids". Nonetheless, chronotopoids are more general, and are not necessarily limited to timelets/spacelets and their fusions. The timelet/spacelet chronotopoid corresponds to the particular way in which the interpretation of physical theory carves the limits of our intuitive understanding of the space and time we inhabit. Other chronotopoids, at levels of 'reality' well above the hypothetical limit, will carve a physical spacetime which corresponds more to the Euclidian, Newtonian, or Minkowski interpretations.

Nonetheless, we can I think argue that "minimal chronotopoids" – minimal spatiotemporal regions - are as 'real' as are rocks, atoms, or grains of sugar.

TO CONCLUDE – THE SPECIOUS PRESENT AGAIN

We can, perhaps, consider the specious present as being 'ontologically' dependent on minimal chronotopoids (that is, made up of some kind of spacetime foam). Orientation in the immediate vicinity of any chronotopoid would be almost undetectable, as the distances and intervals involved would render untenable any classical description of 'causal structure' based on the temporal interval between events. Nonetheless, the overall extent of the specious present allows that a general orientation be detected; this orientation would seem to be given by the direction in which the 'structure' of the immediate contents of the spacetime region tends towards homogeneity. [Further, and entirely unfounded, speculation: could the phenomenal sense of time the passage of time be some kind of 'wave-like' phenomenon arising from increasing local complexity and decreasing complexity on a more general level].

It would seem to follow from the various points we've discussed that within the focal area of the specious present there is no clear order of events, from which it follows that there is neither an internal distinction between past, present, and future, nor a clear 'flow' of time, though there is a general sense of "orientation" - indeed, the specious present so described would seem to resemble (though perhaps not in every particular) the block-universe of eternalism.

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NOTE ON "EPISTEMOLOGICAL REVISION": this is a different, but equally fascinating, area of reflection. I hope to return to it when we consider 'social' models of time.