04.06.2010
"As an empiricist I continue to think of the conceptual scheme of science as a tool, ultimately, for predicting future experience in the light of past experience. Physical objects are conceptually imported into the situation as convenient intermediaries -- not by definition in terms of experience, but simply as irreducible posits comparable, epistemologically, to the gods of Homer. Let me interject that for my part I do, qua lay physicist, believe in physical objects and not in Homer's gods; and I consider it a scientific error to believe otherwise. But in point of epistemological footing the physical objects and the gods differ only in degree and not in kind. Both sorts of entities enter our conception only as cultural posits. The myth of physical objects is epistemologically superior to most in that it has proved more efficacious than other myths as a device for working a manageable structure into the flux of experience."
~WVO Quine, "Two Dogmas of Empiricism"
Note that Quine considers physical objects to be "comparable epistemologically to the gods of Homer". Physical objects - things like chairs, books, stars, stones, people, cities - "enter our conception only as cultural posits": that is, they are rooted in our language and in the intuitive world-view associated with or determined by that language. Physical objects are, of course, far more deeply rooted in our everyday language than are gods (of any degree); the "myth" is therefore all the more pernicious.
M J Cresswell (“Why Objects Exist but Events Occur”, Studia Logica, Volume 45) has suggested that we may distinguish between physical objects and (non-instantaneous) physical events by determining whether or not the "sub-interval property" applies to the entity under consideration. Thus, my copy of "An Introduction to Modal Logic" is a book at every sub-interval of its period of existence (and, logically, at every "instant" of its existence); however, a voyage from Paris to London is not a voyage from Paris to London at any sub-interval of its period of occurrence. The ontology of such entities is pretty straightforward, if we allow mereological fusion: we intuitively treat the book as an enduring three-dimensional entity having all its parts at each instant and the voyage as a perduring four-dimensional entity having a proper part at each instant of its period of existence.
Classically, the identity of the book over time – from instant to instant – can be given by the indiscernibility of identicals: at any distinct times t and t+n, the book has all the same intrinsic, non-relational properties. Of course, such a view is undermined by our everyday experience, to say nothing of our scientific accounts: my copy of "An Introduction to Modal Logic" remains "the same book" despite annotations, coffee-stains, clipped pages etc. The mereological account – that it persists through time by having all its parts at each instant – allows us to circumvent this classic Ship of Theseus problem: it may well be the case that my copy of "An Introduction to Modal Logic" had no annotation on page 24 and an intact back cover at a time t, but that it does have an annotation on page 24 and its back cover is damaged at a time t+n, but this in now way disallows me from claiming that it is one and the same book. Of course, this in no way explains "how" the book should persist from instant to instant – we have yet to suggest a criterion of persistence that can do the job of the indiscernibility of identicals, and it is most unlikely that any candidate would have the logical force of Ind Id. Accounts could stress either the compositional qualities of the entity (its "physical nature"), its causal relations, or its spatial continuity; an effective account would certainly integrate the three criteria.
This allows us to explain how my copy of "An Introduction to Modal Logic" should be "the same" book at two distinct times, but does it allow us to give the ontology of the book considered OVER time? (When, for example, I say "I've had my copy of "An Introduction to Modal Logic" for 15 years now, and it's always been of the greatest use"). On the endurance model, I would seem to be referring either to a number of entities, some of which have an undamaged back cover and some of which don't, or to an entity that both has and does not have an undamaged back cover (relative to certain times). In the former case, the different entities would be at best counterparts; and in the latter, investigation of what it means either for "x to be F" at t or for x to be "F at t" leads us into a wilderness of propositional shenanigans. To escape this latter end, we can - if our ontology is sufficiently flexible (or nominalist) - simply grasp the former horn of the supposed dilemma and hold that the putative "object of reference" can indeed be described as " a number of entities, some of which have an undamaged back cover and some of which don't".
On the mereological view, these "entities" are the (temporal) proper parts of a composite entity, which persists through time by having a three-dimensional part at each instant. Whether we consider the fusion to be nothing more than the sum of its instantaneous parts, or whether we consider the temporal parts to be the result of a decomposition of the fusion, is a matter of metaphysical preference, and would depend largely on our views concerning "instants". For my part, and whether *physical reality* is effectively "gunky" or not, I would say that the Augustinian notion of "instant" has little to do with the pragmatics of reference, and that what evidence we can draw from either psychology or physics tends to undermine a too-realistic understanding of "instants". If expressions somehow correlate with propositions, and true propositions somehow correlate with actualised states of affairs, then the putative referential object of "I've had my copy of "An Introduction to Modal Logic" for 15 years now, and it's always been of the greatest use" is at least temporally correlated with the event which is my utterance – that is, over about one and a half seconds.
I'd hold that such rigid differentiation between "object" and "event" is of little more than linguistic import: many commentators would reserve the term "event" for what are otherwise called "instantaneous changes", and such commentators would consider that "a voyage from Paris to London" is no entity at all (for that matter, they wouldn't necessarily consider an instantaneous event to be an entity). Others would point out that a voyage is a process, and as such is realised by a sequence of states over time, in this case linked both causally and spatially. Yet others could riposte that many physical objects – and particularly living beings – can be described as processes constituted by a sequence of interlinked linked spatial and causal properties; furthermore, our best candidate physical accounts would tend to show that there is no clear distinction to be made between "object", "event", and "process" – and even that such categories break down at orders of magnitude infinitely higher than the "instant" of Augustinian tradition (or the "point" of classical geometry).
Such notions are undoubtedly "local", in the sense that "weight" is local – the notion is entirely meaningful under local conditions at our order of magnitude. A table is a thing; a football match isn't a thing in the same way. Of course, a football match can be a very important thing – but in the same way that football can be an important thing. When I say that football is an important thing, I don't mean "thing" as I would if I said that a table is a thing. Of course, the table is made of pieces of wood, and pieces of wood are things, so is the table one thing or a collection of things? If I say "the table's suffered a lot over the years", am I talking about the table or the pieces of wood? If the table is not identical with the pieces of wood, what is it MORE than the pieces of wood? Is "the table that is more than the pieces of wood" just the contents of a certain continuous region of spacetime have certain topological properties? If it is, what delineates this region of spacetime? Is the delineation due to some intrinsic (possibly geometric, possibly constitutional) property of the table, or to some extrinsic property? If the property is extrinsic, is it purely relational in the sense of being relative to spatiotemporal location, or is it partially conventional (insofar as it is described as being just the contents of that particular region of spacetime)?
What, if any, is the distinction between "Julius Caesar" and "the life of Julius Caesar"?
06.06.2010
"Being realist about the physical world" should imply AT MOST believing that our phenomenal experience of the world is correlated to, emergent on, and largely determined by mind-independent physical occurrences.
If we choose to adopt such a stance, we must first ask ourselves what we mean by "the world" and by "mind-independent physical occurrences", and in what way "phenomenal experience of" the one should be "correlated to and determined by" the other.
What metaphysical assumptions underlie this putative "ground zero" of sophisticated realism?