This is more an objection to the argument from reason as a whole. The response is to say how could mental content necessarily be tied to brain events in such a way that it isn't irrelevant or arbitrary? How could propositional content and the logical relationships between propositions play an important role in neurons firing? It is hard even know what that could mean. This is what would be necessary to respond to the argument from reason. Indeed, it is hard to see how propositional content and logical relations could have any causal power at all (hence those brands of materialist leaning perspectives on the mind that do recognise mental events as non-physical, almost always embrace epiphemomenalism), given a naturalistic understanding of causation, let alone cause other brain/mental states in a manner consistent with reliable logical inference.

Let's not forget that formal reasoning is necessary: if the premises are true then the conclusion must follow. Brain events, like all physical events, are contingent. How could a brain event therefore be tied to mental content in the correct way to trust our reasoning?

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But the physical causes, in this case neurons, don't cause each other according to propostional content and the logical relations between proppsitions. They cause each according to chemical or physical powers or laws. How can we understand that physical causation to in fact to take account of propostional content and logical relations? It doesn't seem to make sense. In your example, the symbols have their meaning from human convention. The physical processes are human made symbols that symbolise a chain of reasoning. In themselves calculators don't reason.

Remember, we need more than that we brain states and mental states happen to align. It can't be fortuitous, because that wouldn't allow us to trust our reason. We need to show why the propostional content and relations between proppsitions must be matched by brain states that cause one mental state to follow another.

But those are propositions, not neural processes. I'm not sure what you mean? Are you arguing for identity theory? Where things like propositional content turn out to be physical? It seems hard to see how propositional content could be physical, given our idea of the physical. Identity theory is not epiphenomenalist, because it identifies mental states and brain states, so the mental states do have causality (it is just they are physical). The problem is understanding how neurons or atoms or whatever can be identical to propositions and how the physical causation involved can act according to propositional content and logical laws. It doesn't seem to make sense.

But with the ink blots, the meaning is derivative. It comes from humans. There's no intrinsic meaning in writing, or in the symbols on a calculator, except what humans assign to it. I don't see how this would be any different for neurons.

Jeremy Taylor wrote:

But those are propositions, not neural processes. I'm not sure what you mean? Are you arguing for identity theory? Where things like propositional content turn out to be physical? It seems hard to see how propositional content could be physical, given our idea of the physical. Identity theory is not epiphenomenalist, because it identifies mental states and brain states, so the mental states do have causality (it is just they are physical). The problem is understanding how neurons or atoms or whatever can be identical to propositions and how the physical causation involved can act according to propositional content and logical laws. It doesn't seem to make sense.

Okay wow, I totally missed the strength of your objection the first time I read this a couple days back. I believe I'm grasping it correctly. You're arguing that the firing patterns of certain clumps of neurons could not account for the logical relations between propositions which are mental. That is, if the mental is reducible to mere neurons firing then it's hard to see how the material causal relations of these neurons could account for the logical relations of propositions--i.e., it seems impossible to think of neural firing A logically entailing neural firing B. This would be like saying, in a series of collapsing dominoes, that domino A logically entails domino B--there are physical causal relations between the dominoes, but such relations are completely devoid of logical relations. So, given this view, it seems as if a purely material causal process of neural firing patterns could not account for our everyday use of propositional logic.

I think, however, if they were so inclined to preserve materialism, they could perhaps argue that logical relations are ultimately illusory and all that exists are the neural causal relations. That is, when neural firing pattern A (representing "All men are mortal"), considered with neural firing pattern B ("Socrates is a man), which in turn causes neural firing pattern C ("Therefore Socrates is mortal"), is not really a logical relation. We are only given the illusory impression that it is a logical relation but it is purely reducible to material causation.