Because I am not a philosopher, I posed your inquiry to Dr. Gordon. His response follows:
Thanks for forwarding your student’s excellent question. The reasoning used in praxeology is of different kinds. Sometimes, the issue is what is involved in a concept? For example, “an action involves the use of means to achieve an end.” This is not deduced from a premise.” Rather, one thinks about the concept of action and asks, is this statement true? Note that this is not a matter of stipulating a definition: rather, the concept is taken as given to consciousness and then one inquires about the nature of the concept. Doing this is not preliminary to formalization. Thinking about the nature of the concept is the praxeological reasoning: it isn’t an informal version of something else.
In other cases, there is reasoning from premises, as in the argument for the law of return or some of the arguments for time preference. I am not sure what your student means by a “cumulative premise”. It isn’t that conclusions are continually added to the concept of action, and then other propositions deduced from this combined premise. Rather, sometimes there is deduction of conclusions from premises, at other times what is done is thinking about the meaning of a concept. Your student is wrongly trying to look for parallels to the sort of formal structure he is used to from other classes.