Let’s assume for a moment that the imagination is physical. That is, let’s assume that Thomas Nagel is completely wrong in his famous argument that qualia (sensory experience as it feels to the person doing the sensing) cannot possibly be reduced to brain-functions without seriously altering the definition of brain-function (and even science).
Of course, I think Nagel’s argument is obviously true, but I’ve argued that point elsewhere. For now, I’m interested in a different aspect of the mind: intellect.
People who haven’t thought about the subject, and even too many modern philosophers, conflate the imagination and the intellect. It is easy for people to simply assume that rational thought and picturing things in one’s mind is the same thing. But a little rational thought shows this to be false.
Take, for instance, the classic example of geometry. It is perfectly obvious, even to a child, that the concept of triangularity is different from any particular triangle one can imagine. An imagined triangle, after all, will be either isosceles, scalene, or equilateral. It will be of a particular color. It will be either hollow or filled in. And so on it goes.
But the rational concept of a triangle is not like that. It is not particular, but universal. It applies equally to any triangle one can picture.
In addition to this difference, there is a precision in rational thought that isn’t present in the imagination. It probably isn’t possible to produce a mental image of a crowd of 10,000 people that is different than a mental image of a crowd of 10,001. But the rational mind has no trouble understanding the difference.
What this shows isn’t that there is no connection between the imagination and the intellect. Of course there is. Rather, it shows that they are different things.
And this is problematic, because it is even harder to show that the intellect is material than to show that the qualia of the imagination are material.
Before I get to the reasons, I do want to interject with something that can’t be said often enough. This is not because science hasn’t been able to do this yet. It is because it would contradict science to ever do this. To argue that future science will answer the problem of intellect is no more rational than arguing that science will one day overcome the need to do math. This argument, as in other places, is borne out of a misunderstanding of science.
As to the intellect, there are at least two problems for the materialist:
First, all materialist takes on thought, matter, brain-function, etc. have failed to account for the universality of rational concepts. Even given the dubious claim that they can account for this or that imagined object, they can only account for a particular instance of a thing. Actual universal abstraction is a completely different kind of thing from qualia.
To grab a quick illustration, what counts as a valid response from a computer program depends entirely on what the programmers and users of the computers want it to do. (Some eccentric person, after all, could build a computer that is meant to melt its wiring, and to respond to every input with “5”.)
There is simply no fact of the matter about what counts as proper computer functioning apart from the human minds that design, build, and use computers. And this is because physical systems (like computers) don’t reference abstract, universal concepts. They merely operate in patterns that humans interpret as representing universals.
And this has, it seems, drifted into the second reason why the intellect is not material: there is absolutely nothing about the physical facts of a system that make it about anything in the way that thoughts are about things.
We may say that the aforementioned computer is adding, but that is only because we take certain symbols and patterns of electron movement to represent adding. The idea that what it is doing counts as adding is an arbitrary decision made by computer engineers and accepted by computer users.
A useful fiction, indeed. But it is a fiction all the same to say that the computer is adding simply by virtue of its physical properties.
Real thought has intrinsically what computers have only by convention. And this, as above, is not because our current technology isn’t yet sophisticated enough. This is a difference of kind–rather than degree.
But the real point here isn’t about computers. It is about rational thought: it is something altogether different from what we find in the material world (as science defines the material).
And then, of course, there’s this irony:
Demanding that rational thought is nothing more than physical processes is, for the reasons mentioned above, demanding that there is no good reason to trust one’s thoughts. After all, saying that thought is nothing but chemical reactions in the brain is to say that there’s no place for rationality to be involved in the process.