I have been discussing the nature and truth of the proposition that humans act with a nominalist. I have not been able to respond to his criticism of the truth of synthetic a priori categories, ideas, concepts, etc. It seems to me to be perfectly valid criticism, but I am interested to hear what other people think.
Mises says, "The a priori categories are not innate ideas. What the ... child inherits from his parents are not any categories, ideas, or concepts, but the human mind that has the capacity to learn and to conceive ideas, the capacity to make its bearer behave as a human being, i.e., to act." How does Mises know this, and what does he mean by the mind?
Mises rightly criticised treating imaginary things (collectives, analogies, metaphors, etc.) as real and warns us to be very cautious when using fictitious auxiliary constructs to explain things, but has he not himself committed the fallacy of treating the mind as a real thing? The mind does not exist; it has no existence as a noun. We can "mind" our step, but this "mind" has no structure; it is a verb. Yet Mises talks of the structure of the mind repeatedly and it is central to his claim that the proposition that humans act is true a priori.
Is Mises not mistaken in talking about synthetic things being true a priori and is it not due to his incorrect use of the mind as a real thing? Comments appreciated.
