The neuroscientist Bill Skaggs has an interesting post at Scientia Salon which prompted the following piece, somewhat too large and too late for a SciSal comment.
That the world is divided into objects seems by most philosophers to be taken as a given. Quite what counts as an object or substance and why is not considered. I think it's an important question. Philosophers discuss 'existence' a good deal, which they contrast with 'non-existence'. But the etymology is ex+sistere---to stand out. So the contrast should be with that which doesn't stand out, which we might call 'undifferentiated stuff', or 'the bulk', or even 'prime matter', rather than 'nothing'. However, I don't think our concern is with the ontology of objects, but rather their epistemology.
The commenters at SciSal had some fun with the science fiction of personal identity and the self. But I think Bill is right to emphasise the neural basis of our knowledge of objecthood and identity over time for external material objects. This must surely have appeared earlier in evolutionary history than the self. If we can get some understanding of how neural structures could represent external objects for a non-self-conscious creature, then we might be able to see a way forward to understanding how a similar architecture could come to represent the creature for itself. But this definitely comes later.
It's clear that we have to hypothesise that there are neural surrogates for enduring objects in the environment, and probably more temporary surrogates for objects we encounter from moment to moment to which we direct our attention. These must arise through sensory contact---in philosophical terms they constitute Russell's knowledge by acquaintance. Likewise surrogates for the objects of knowledge by description---those things we hear about through language and other representational media, including historical and fictional entities.
If we are prepared to do this, then I think we obtain solutions to several paradoxes in the philosophy of language, including Frege's puzzle of Hesperus and Phosphorus from On Sense and Reference, and Kripke's paradoxes in A Puzzle about Belief. I think we can say that all these puzzles have a common form: a failure of the object extraction/surrogate construction process adequately to model the objects. Ancient astronomers find two celestial bodies, Hesperus the evening star and Phosphorus the morning star, rather than just the one planet, Venus; Pierre finds two cities, London the ugly and Londres the jolie; Peter finds two Paderewskis, one the musician, and one the politician. Frege's puzzle, if I have understood it, is that if proper names contribute their referents and nothing more to the meaning of a sentence, then 'Hesperus is Phosphorus' should be equally as informative as 'Hesperus is Hesperus', and it clearly is more so. We can resolve the puzzle by saying that the proper name 'Hesperus' refers indirectly to Venus via the neural surrogate Hesperus* that encodes the information 'rises first in the evening'. We can imagine that hearing or reading the word 'Hesperus' causes some kind of excitation of the structure Hesperus*. Hearing 'Hesperus is Phosphorus' must then cause a degree of cognitive dissonance leading to a possible denial. For we can suppose that the two structures Hesperus* and Phosphorus* are distinguishable at the neural level, that is, some neural signal representing the equality or otherwise of Hesperus* and Phosphorus* must be available. This may be where Bill's unique identifiers can play a part. If we are to come to believe that Hesperus really is the same thing as Phosphorus then the neural surrogates Hesperus* and Phosphorus* have somehow to be submerged into a single object surrogate which encodes both 'rises first in the evening' and 'sets last in the morning' and which responds to both proper names. It seems plausible that this can be achieved by growing new neural interconnections.
Likewise, we can also take some of the sting out of Kripke's paradoxes. Kripke insists that the question Does Pierre believe London is pretty? must have a definite answer. For Pierre assents to 'London is not pretty' and also to 'Londres est jolie' and London and Londres refer to the same city, don't they? But we can resist this insistence. We can say that Kripke is reporting Pierre's belief in terms of his own assay of cities, in which London and Londres are one, rather than in terms of Pierre's mistaken assay in which London and Londres are two. If Pierre and Kripke cannot agree on what cities there are and how to name them, then how can we expect them to agree on the properties of cities?
I should emphasise that this is not just a non-Millian theory of reference. It's also non-descriptive. It doesn't substitute a description for 'Hesperus' at the level of sentences. The usual arguments against descriptivism assume just this. Instead, it proposes intermediaries between language and objects through which external reference is mediated.