AFR Defended (poorly) by Gilson

Tom Gilson has produced a defense of the Argument From Reason that closely mirrors the thinking of Victor Reppert.  It amounts to an argument from ignorance of science.  I will summarize Gilson's points.  First, his argument stated formally:

P1: At the foundational, atomic or molecular level (under physicalism) the physical brain operates without regard to rationality.

P2: At the foundational, atomic or molecular level (under physicalism) the physical brain operates without regard to truth-bearers.

P3: At the macro level, under physicalism, the physical brain operates without connection to truth-bearers, unless some truth-bearing capacity is introduced from a non-physical source.

P4: At the macro level, thought has no connection to truth-bearers, unless some truth-bearing capacity is introduced from a non-physical source.

P5: Thought has no connection to truth (under physicalism).

 In his discussion of P1 and P2, Gilson says:

Thoughts and beliefs are also not truth-bearers; yet again, it is their content, not their momentary instantiations, that carries truth. This leads us again back to propositions, which are the content of thoughts and beliefs. ... there also must be a truth-maker--a state of affairs such that the truth-bearer (the proposition) expresses a true fact about that state of affairs.

And he offers a quote from Moreland and Craig:

"The intentionality of a proposition is a natural affinity or intrinsic directedness towards its intentional object., i.e., the specific state of affairs it picks out. Thus truth-makers make truth-bearers true, not in the sense that the former stand in an efficient causal relation with the latter and cause them to be true. Rather, the truth-bearer, the proposition, picks out a specific state of affairs due to the proposition's intrinsic intentionality, and that specific state of affairs "makes" the proposition true just in case it actually is the way the proposition represents it to be."

Up to this point in the discussion, I can accept the notions of "truth-makers" and "truth-bearers", but I disagree with the distinction he makes between thoughts and beliefs and truth-bearers.  Gilson seems to be saying that a thought or belief is just a physical medium, like a sentence written on paper, and that the content of the thought, the truth-bearer is separate from the medium.  I don't buy it.  Most people would say that a sentence written on paper expresses a thought.  In other words, the thought is the content that is expressed by the sentence.  Now Gilson is claiming that a thought is more like a sentence on paper, a medium that carries content, and the content of the thought is something different from that.  He says the content of a thought is a proposition. 

Propositions are not physical. ... the proposition expressed by, "AC circuits can by analyzed through complex number mathematics" was true long before AC circuits or complex number mathematics were discovered.

This seems to be begging the question.  He has declared that the content of thoughts is not physical, but exists for all eternity as a Platonic object.  However, it is not the case that a proposition was true long before it was ever proposed.  In order for a proposition to exist, it must be proposed by a person.  The definition of 'proposition' is: "a statement or assertion that expresses a judgment or opinion."  In other words, by definition, a proposition is like a sentence written on paper.  It expresses a thought, not the other way around, as Gilson would have us believe.  If it hasn't been stated or asserted, the proposition doesn't exist.  If it doesn't exist, it can't have the property of being true or false.

These properties of propositions are not seriously in dispute among people who hold to a correspondence theory of truth.

Oh, really?  This is the description of correspondence theory of truth given in Wikipedia:

The correspondence theory of truth states that the truth or falsity of a statement is determined only by how it relates to the world and whether it accurately describes (i.e., corresponds with) that world. - Wiki

So the correspondence theory of truth merely gives us an understanding of what it means to say that a proposition is true.  It does not hold that propositions exist in a Platonic realm, independent of the people who create them.  The existence of Platonic objects is seriously doubted by philosophers and scientists alike, even if they subscribe to the correspondence theory of truth.  Gilson is wrong to assert that propositions are non-physical and that there is no serious dispute about this.  There is serious dispute about it.

Gilson goes on to discuss P3 and P4:

Whence, then, under physicalism, does a physical event find its connection to truth, or to any proposition at all? ... Brain events are composed of a hierarchical series of law and chance relations. Law and chance seem to be the only things operating to produce brain events ... Law and chance, then seem to be the only things operating to produce thoughts. But law and chance have no regard for propositions ... If the only things operating to produce thoughts, from the micro level on up to the macro level, are things that have no regard for (no connection to) propositions, then there is no way for thoughts to have any connection to propositions.

Here, Gilson has committed another serious blunder.  He starts out with an assertion about what happens at the micro-level, and then leaps to the conclusion that nothing more than that happens at the macro-level.  But this is demonstrably false.  He completely ignores the dynamics involved in complex physical interactions.

Or do you suggest that there is something at the level of thought, at the macro level, that could overrule physical law and quantum chance events?

No, it doesn't overrule, it supervenes.  But the fundamental laws alone are insufficient to describe the dynamics.  That requires a higher level of analysis, but there is no implication that the higher level description of complex physical dynamics doesn't exist, or that it overrides the more basic laws.

As an example, consider a tornado.  It consists of molecules of air and water.  If we only consider the most fundamental physical laws - Newton's equations relating force, mass, and acceleration, or Boyle's laws relating temperature, pressure and volume, we would be hard-pressed to explain the dynamics involved in making a tornado.  But we know that there is a higher level of analysis that goes beyond the fundamental laws.  This is not an act of God, nor is it a violation of the laws of physics.  It is a consequence of fundamental physical laws.

How could it do that? It seems that the propositional content of thoughts, if such a thing could exist under your physicalism, would be causally effete, ineffective, in the face of the inexorable, unstoppable, undirected operation of law and chance. ... One might propose that the non-physical source of P3 and P4 is something cast up out of just physical conditions--complexity, perhaps. It behooves the person proposing that possibility to show how complex interactions taking place just through law and chance can find a connection to propositions.

Now we get back to Gilson's assertion that propositions are immaterial objects that exist in a Platonic realm, based on the idea that intentionality is non-physical.  But intentionality is purely physical.  As I have discussed previously, intentionality consists of physical connections in the brain.  It is the associative connections between neuronal elements that encode concepts in the physical matter of the brain.  These neuronal connections form the basis of meaning and "aboutness".  What Gilson is doing amounts to denial of any scientific explanations or laws beyond the most fundamental.  But his refusal to consider them does not justify his logical conclusions.

In conclusion, what Gilson has done is make an argument from ignorance, based on his unsupported theistic assumptions about the existence of non-physical entities.  The reader will note that while he argues vehemently against the equivalence of physical thoughts and non-physical propositions, he offers absolutely no support for his assertions that they are non-physical.  This is simply a theistic assumption, and it begs the question.