A theory of gravity is supposed to tell a story about how physical objects are attracted to each other, by some agreed measure of attraction, and to explain and predict observable phenomena based on this story. So a theory of choice, I take it, should tell a story about how choices are made, by some agree measure of choice, and explain and predict observable phenomena based on this story. The agreed measure of choice for most economists appears to be observed behavior. Gravitational physics is a field where theories (pl.) of gravity are pitted against each other to determine their relative usefulness. We would not say "gravitataional physics is the theory of gravity" for a few reasons. I'll mention two. First, it is a field of study, not a theory. Second, theories (plural) are studied in this field of study, not "the" theory. A given theory distinguishes itself from other theories by ruling in and out various factual claims. A theory of gravity that failed to rule out some imaginable, observable (though possibly in a frequentist sense) behaviors of physical bodies would be rightfully dismissed. It is not a scientific theory. A theory of choice should similarly be dismissed if it cannot rule out some imaginable, observable human behaviors. I understand Pat Gunning to insist on two claims. The first, which he seems inclined to focus on, is a very weak claim: that we often find it useful to interpret human behavior as purposive. Nobody has disputed this, I think. As I said earlier, this kind of folk psychology is pervasive and does not distinguish economists from others except, as Pat suggests, many economists are inclined to spend a lot of time thinking about what might follow from this. Of course we also find it useful to interpret animal behavior as purposive, and even evolutionary biologists have found teleological thinking to be provisionally useful. if we find such teleological thinking useful, that is justification enough for using it. Provisionally. But as our profession has proved (and as the recent HES list discussion highlights), NO behavior is ruled out by the brute admonition to interpret behavior as purposive. For example, in violation of the Stigler and Becker (1977) admonition to economists, James will "explain" suicide bombers by giving them special utility functions (real ones, apparently!) to maximize. Thus even folk psychology, which Pat proposed as the root of economics, gains usefulness only when supplemented substantially with concrete content. A "theory of choice" cannot simply be the assertion that observed behavior is purposive. This brute assertion has no empirical content and by itself does not even suggest any models of behavior. That is why I and others on this list have insisted that even that part of economics that focuses on purposive behavior---let's call it "choice-theoretic" economics---gets its content elsewhere. The second, strong claim Pat (and others) have made is the economics *is* the theory of choice. I previously raised questions about what kind of claim this is, and others on the list have done so as well. I suppose it is intended as a demarcation criterion for the profession---a kind of "do things my way or you're not an economist." I am not really interested in demarcation criteria, but this one has serious difficulties, as it is evident that many professional economists are engaged in activities not meeting this criterion for belonging to the profession. Perhaps an even more powerful objection to any proposal that "economics is the theory of choice" is that *identifying* a field of study with a single theory is a suspect move at many levels. Cheers, Alan Isaac