Feser's Philosophy of Mind, #3

This chapter deals with materialistic views of mind, namely that reality, and therefore the mind:

consists of purely material or physical objects, processes, and properties, operating according to the same basic physical laws and thereby susceptible of explanation via physical science. There is, in short, no such thing as immaterial substance, or soul, or spirit, nor any aspect of human nature which, in principle, elude explanation in purely physical terms.

I note, purely in passing, that the second sentence doesn't necessarily follow from the first. In any case, Feser then proceeds to argue that it is difficult to see how things like cultural conventions, for example, are:

… hard to reduce to the properties of molecules in motion.


There seems to be no way to match up sets of logically interrelated mental states with sets of merely causally interrelated brain states, and thus no way to reduce the mental to the physical.

Here is how it's done. We have no problem understanding that there are quarks and electrons. We have no problem understanding that quarks combine to form protons and neutrons, and that protons, neutrons, and electrons form atoms. Atoms form trees and stars, bacteria and brains.

Instead of combing things into more things, consider the case where two things are "combined" into one of the two things. Consider the physical process where an apple and an apple combine to an orange, and apple and an orange combine to an apple, an orange and an apple combine to an orange, and an orange and an orange combine into an apple. Or consider the case where an apple and an apple combine to orange, while apple and orange, orange and apple, and orange and orange combine to apple. There are sixteen ways for these combinations to happen. We can demonstrate that repeated application of either of two of these processes can reproduce all of the others.

This is a purely physical process. Instead of using apples and oranges, we can use more or fewer electrons flowing through a wire. We can use variable resistors to make a physical process that combines more and fewer electrons just like we combined oranges and apples. Let's call this collection of variable resistors and wires a "device". These devices can be strung together into complex networks.
We can show that arrangements of these devices are equivalent to neurons and computer gates. Furthermore, and this is one of two key insights, arranging devices and wires one way gives one behavior; arranging devices and wires another results in a different behavior.

This is important, because we normally think of a computer as an arrangement of wires and devices that takes a program as input, performs the steps in the program, and produces a result. This leads us to believe that a computer cannot do anything without programming. Feser falls into this way of thinking when he writes:

A computer program is something abstract – a mathematical structure that can be understood and specified, on paper or in the programmer’s mind, long before anyone implements it in a machine.

While this isn't wrong, it hides the key concept that the arrangement of the wires and devices is the program. No external program is necessary. If it were cost effective, instead of writing abstract programs that run on a general purpose computer, we could custom build an arrangement of wires and devices for each program we wished to run.

Once we understand that the physical network itself is the program, we have to ask how we can get meaning out of networks of apples and oranges or high and low voltages. Consider the network that given an apple and an apple, or an orange and an orange, produces an apple and when given an apple and an orange or an orange and an apple produces an orange. This is equivalent to the question "are the inputs equal" with "apple" being assumed to be "yes". We could just as easily chose the network that takes apple and apple or orange and orange and outputs orange. The choice of which network to use is completely arbitrary, but networks that use this convention can now be constructed that can compare two things for equality. This is the second key insight. Meaning is achieved by building a network that uses one of the two inputs to answer the question "are these things equal?" And once you have that, you have the basis for constructing systems that can, for example, associate sights with sounds.

One network can wag a tail at the enjoyment of a bone, another network can contemplate the ontology of thought. Dogs don't discuss epistemology simply because their brain wiring is insufficient for the task.

So the question isn't "is thought a physical process?" It certainly is. Logic is built into the very fabric of reality. The "devices" are just logic gates. The astounding thing is that a network of these gates can recognize and describe themselves. Furthermore, our brains aren't capable of proving that logic can be separated from reality. Every attempt to do so changes reality such that we destroy our ability to think.

The real question is "how did these complex networks arise in the first place?" But with the current state of the art, the answer to that question depends very much on your philosophical assumptions.
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