The last entry discussed realism, the view that there exist universals (traditionally known as 'forms'). As we saw, on realism, objects that share properties, e.g. two red objects, are said to exemplify or participate in the same universal, in this case, the universal 'redness'. Realists generally regard universals as abstract, existing in a realm causally disconnected from the realm of concrete things that we exist in.
I argued that a benefit of realism is its potential to explain why the world contains what might be called 'real resemblance groupings'. Things in the world, as it were, 'come in boxes', i.e. in natural categories that our concepts try to demarcate. Trope nominalists explain this by saying that things belong to the same real resemblance groupings because the individual properties ('tropes') they have resemble each other (e.g. the redness of object 1 resembles the redness of object 2), and leave it at that, leaving resemblance as an unexplained brute fact. The realist explanation goes further, as it explains why resemblance exists at all. Resemblance between concrete things in the world is ultimately explained by their participation in abstract universals.
However, I noted that realism faced various troubles. I will mention two:
1. Unintelligibility: the reader may have noticed that, frustratingly, I have used phrases like 'participate in' and 'exemplify' without ever explaining their meaning. Unfortunately, such sloppiness on my part reflects the very real problem that we are rarely, if ever, told by realists what it means for a thing to 'exemplify' or 'participate in' a universal. This is a serious weakness. Recall, the exemplification of / participation in universals is supposed to explain the existence of real resemblance groupings. But a purported 'explanation' can't do any explanatory work if it is unintelligible. Suppose my 'explanation' for the existence of real resemblance groupings is that they are 'troxed by gromphles'. It wouldn't do for me to criticize trope nominalists for offering an incomplete explanation of real resemblance groupings, as the 'explanation' I put forward is no explanation at all, since its meaning (if it has one) is impossible to understand. Of course, realists may answer that terms like 'exemplify' and 'participate in' are primitive, meaningful but impossible to analyze (like, perhaps, 'exists'). But in doing so they will be hard-pressed to convince their audience of the reality of what they are talking about. If I don't understand what the terms of the alleged explanation mean, I will never be able to accept the explanation itself.
2. Causal isolation: realists typically hold that universals are abstract, by which they mean that they are outside of space and time, and therefore causally isolated from the world of concrete things. That is, they cannot causally interact with such things. Two subproblems arise from this:
2a. if universals can't causally interact with concrete things, how can they be responsible for the real resemblance groupings in which concrete things find themselves?
2b. since you and I are concrete things, universals aren't causally related to us either. But this would seemingly make it impossible for us to know about them. Philosophers tend to accept the so-called 'causal theory of knowledge', which says that, for a knower to know a fact, there must be some sort of causal relationship between the knower and that which he knows. For example, I know that there is a cup on my desk because the cup's being on my desk causes me to have a perceptual experience of the cup.
It should be clear that the problems raised here are more than just unfortunate consequences of realism, that we just have to accept because we need realism to explain real resemblance groupings. Indeed, if these problems aren't dealt with, it turns out that realism can't explain anything at all.
I will now argue that these problems don't arise if the realist also believes in a demiurge. The demiurge (demiorgos = 'craftsman'), for Plato, was a God of some sort, who creates the concrete things of this world out of preexisting raw materials by modelling them on the perfect forms. Thus, things that belong to same real resemblance grouping do so because they were ultimately modeled according to the same form. Later platonists often interpreted the forms as eternal ideas in the demiurge's mind.
How does this more ancient variety of realism fare with respect to the foregoing problems?
1. Unintelligibility: to 'participate in' a universal is to be understood as having been modeled on this universal. This is much more intelligible than in the demiurge-less version of realism, because we know what it means for something to be modeled on something else. Moreover, if we take the later platonist view that sees universals as divine ideas, realism becomes even more intelligible, since we know what ideas are and we know what it means to model things on them (this current blog article has itself been modeled on my idea of a blog article on the importance of the demiurge to realism).
NB: this does not commit the realist to believing that the demiurge directly creates the members of real resemblance groupings, through spontaneous acts of creation. The demiurge could instead indirectly create them, by setting up the initial conditions and laws that would bring about the desired groupings. Hence, the theistic realism described here is compatible with scientific views of the development of the universe (more on this in another entry).
2. Causal isolation: in Plato's realism, the demiurge acts as a kind of causal bridge between the forms and the realm of concrete things. The demiurge contemplates the forms and crafts concrete things that reflect them. So, the universals are causally responsible insofar as they inspire the demiurge to create as he does.
Moreover, since real resemblance groupings are ultimately causally linked to the universals via the demiurge, the epistemic problem disappears as well. We can know about them by inferring their existence from the real resemblance groupings for which they are ultimately causally responsible.
If I am correct that this theistic realism has what it takes to deal with the problems of unintelligibility and causal isolation, the implications are significant. For one thing, it would mean that realists should think twice before minimizing the importance of the demiurge to Plato's original theory, to which they owe their realism. This may mean being compelled to choose between realism and atheism, which would be bad news for realists openly hostile to theism, like Russell. For another, this provides natural theologians with the basic constituents of an argument for theism: if we need universals, but can't have them without theism, then it looks like we need theism too.