I think that if there is such a thing as x-rationality, its heart is that mathematical models of rationality based on probability and decision theory are the correct measure against which we compare our own efforts.
At which point you run into a problem of formalization and choice of parameters, which is the same process of ape-brain-based decision-making. A statement that in some sense, decision theory/​probability theory math is the correct way of looking at things, is somewhat useful, but doesn’t give the ultimate measure (and lacks so much important detail). Since x-rationality is about human decision-making, a large part of it is extracting correct decisions out of your native architecture, even if these decisions are applied to formalization of problems in math.
I think that if there is such a thing as x-rationality, its heart is that mathematical models of rationality based on probability and decision theory are the correct measure against which we compare our own efforts.
At which point you run into a problem of formalization and choice of parameters, which is the same process of ape-brain-based decision-making. A statement that in some sense, decision theory/​probability theory math is the correct way of looking at things, is somewhat useful, but doesn’t give the ultimate measure (and lacks so much important detail). Since x-rationality is about human decision-making, a large part of it is extracting correct decisions out of your native architecture, even if these decisions are applied to formalization of problems in math.