In a 1950 paper, Paul Samuelson wrote:
The most rational man I ever met, whom I shall call Ysidro [when] told that he did not satisfy all of the v. Neumann-Morgenstern axioms, [..] replied that he thought it more rational to satisfy his preferences and let the axioms satisfy themselves.
This introduced in the extensive correspondence between Samuelson, Savage, Marschak, Baumol, and Friedman the idea of the “Ysidro Man” or “Ysidro functions.” In the letters (but not in published print) Samuelson also introduced his mother – as the non-economist acting on her common sense. Thus, for instance, Marschak would discuss with Baumol how best to axiomatize the behavior of Samuelson’s mother.
These archetypes are more commonly labelled homo economicus and homo sapiens – very dull terms indeed (and why the Latin anyway?). So, from now on, when we talk about the homo economicus let’s instead ask: What would Ysidro do? And when criticizing that economic conception as unrealistic, let’s do that by referring to what Samuelson’s mother would do.
History of Economics Playground Redux 
The latin terms might be pretentious, but I wonder if Samuelson making his mom into an ideal type is not even more so…
Aye, true. But then, a bit of change every now and then may be refreshing. It makes it more intuitive as well.
I just had an image of this debate, where someone turns to Samuelson and says ‘your mother is a seperating hyperplane’ … and they went with it.
Sorry
Hicks and Samuelson were for example instrumental in mainstreaming Keynesian economics..Macroeconomics influenced the neoclassical synthesis from the other direction undermining foundations of classical economic theory such as and assumptions about such as the necessity for a hard-money standard.