chloe732:
Here’s my take:
Mathematics is the exact science of spatiotemporal nature. According to Heisenberg:
“It may be said that classical physics is just that idealization in which we can speak about parts of the world without any reference to ourselves.” (Physics and Philosophy)
So the idea is that mathematical logic refers to a realm, an ideal realm, that is independent of human action. The idea is that whether a planet is over here or over there is really not important to human well-being. Such an event is thought to be neutral with respect to human happiness and unhappiness, human satisfaction and dissatisfaction, human intention, human well-being, etc.. Thus, the formal logic of nature, when nature is conceived as independent of human intention, is “not meaningful.” This logic applies to a realm absent human intention, and thus absent the categories of human action.
By contrast, the concepts of praxeology are human meaning categories. They are definitely categories that refer to human action and human intention.
Human action is the phenomenon of “aiming at ends.” In this formal system, there is a category or conception of “what the actor has” (the state of affairs that exists now for the actor), and, “what the actor is aiming for” (the state of affairs the actor is aiming for).
These categories (what I have now, versus what I want) are human meaning categories. They matter to me, or to the actor concerned. They are not, as Heisenberg writes, an idealization in which we can speak about the world without any reference to our selves. Quite the contrary, these concepts directly refer to ourselves: our wants and our attainments.
So I would interpret Rothbard (at this stage of his career where he is a student of Mises), as trying to make the point that the concepts of praxeology are human meaning concepts (striving, attainment, value, supply, means, ends, happiness, unhappiness, etc…), whereas the concepts of mathematics, dealing with the location of objects conceived to be independent of human intention (1, 2, 3, x, y, z, etc…), are not concepts of human meaning.
That is what I believe he is trying to convey.