On occasion, I’ve been accused of being closed-minded. (Shocking, I know.) Frequently the reason is not seriously considering non-physical propositions, a perception of rigid physicalism. However, as I’ve noted before, I’m actually not entirely comfortable with the “physicalist” label (or “materialist”, or other synonyms or near synonyms). While it’s fairly accurate as to my working assumptions, it actually doesn’t represent a fundamental commitment.
My actual commitment is empiricism. By “empiricism” here, I don’t necessarily mean physical measurement, but conscious experience, specifically reproducible or verifiable experience, and inferred theories that can predict future experiences, with an accuracy better than alternate theories, or at least better than random chance. I do generally assume physicalism is true, mainly because many physical propositions seem able to meet this standard, where non-physical ones seem to struggle with it.
But that raises a question. Are there any non-physical propositions that do meet the standard? It depends on what we’re willing to consider non-physical. In the Chalmers post a few weeks ago, I noted that we could interpret his views in a platonic or abstract fashion, in which case the differences between him and a functionalist might collapse into differences in terminology. Although as I also noted, neither Chalmers nor Dennett would agree.
And this bridge between the views depends on your attitude toward platonism. Note that “platonism” with a small ‘p’ doesn’t really refer to the philosophy of Plato, but to a modern outlook that regards abstract concepts as real. This is sometimes described as real in a separate platonic realm, which many misinterpret as meaning a physical existence in a parallel universe or something.
But in modern platonism, abstract objects are held to have no spatio-temporal properties, and to be causally inert. If they have an existence, it is one completely separate from time and space. It’s not even right to say they’re “outside” of time and space, because that implies a physical location, something they don’t have.
What are examples of these abstract objects? Numbers, mathematical relations, properties such as redness, structures, patterns, etc. Under platonism, these things are held to have a non-physical existence. For the Chalmers outlook, the property one is important since he often refers to his view as property dualism.
But is platonism true? One of the the strongest arguments for it appears to be the way we talk about abstract objects. We refer to concepts like “7” as though they have an existence separate and apart from a pattern of seven objects. We refer to structures and properties in much the same way. The fact that we can discuss “redness” coherently seems to imply we accept that property as having an independent existence.
But this assumes that analyzing language is in any way meaningful for what’s real. At best, it might just show our intuitions, intuitions we might not even believe. For instance, we refer to things like the sun “rising” and “setting” all the time without seriously thinking that the sun is moving around us (at least since Copernicus and Galileo). It might be that all this usage should be viewed as metaphorical, and abstract objects as “useful fictions”.
But the dividing line between a useful fiction and a real concept seems like a blurry one. The more useful a concept is, particularly one useful in an epistemic fashion, the harder it seems to dismiss as a fiction. We reach a point where we have to invest a lot of energy in explaining why it’s not real.
That said, a strong case against platonism is also an epistemic one. If minds exist in this universe, and abstract objects exist without any spatio-temporal aspects, and are causally inert, how can we know about them? We could say the mind is capable of accessing abstract objects, but this implies something super-physical about it. The relevant physics appear to be causally closed, and this proposition wouldn’t meet the empiricism criteria above.
The more usual defense is that we infer the existence of abstract objects by what we observe in the physical world, by the patterns and relations we see there. But if that’s how we come to know about abstract objects, why do we actually need the separate abstract objects themselves? Why can’t we just get by with the models in our mind and the physical patterns they’re based on?
This last point has long been what makes me leery of platonism. A ruthless application of Occam’s razor seems to make it disappear in a flash of parsimony. It doesn’t seem necessary. And given how far some people have tried to run with it, this seems important.
All that said, this is a case where I’m not confident in my conclusion, at least not yet. I still wonder if its pragmatic value might not imply ontology. Everything in physics above the level of fundamental forces and quantum fields seems to exist as structure and function, a pattern of lower level constituents.
In many cases, these structures and functions, such as wings or the shape of fish, seem convergent. These convergences could be seen as implying that the converged structure has an independent reality. Of course, these are optimal energy structures that emerge from the laws of physics, but then do the laws themselves have an independent reality aside from the physical patterns and regularities? Are they themselves abstract entities?
And the fact that large portions of the mathematics profession are mathematical platonists gives me pause. Mathematicians seem convinced that they’re discovering something, not developing tools in some nominalist sense, although the dividing line between invention and discovery itself seems pretty blurry.
If platonism is true, then we have a non-physical reality, and properties such as consciousness (the property of being conscious) could be said to exist non-physically in a platonic sense. To be sure, this is a far more limited sense of non-physical than many advocates of dualism envision.
Interestingly, Chalmers himself does not appear to be a platonist, but appears to consider the question of the existence of abstract objects to have no fact of the matter answer, espousing a view called ontological anti-realism. Given my own instrumentalist leanings, I may have to investigate this view. But it also implies my attempt at steel-manning his argument is probably fruitless.
What do you think? Do you see other arguments for platonism? Or against? Or is the whole thing just hopeless navel-gazing?