Ah, so we don't really disagree at all---or, at least not much. It's my fault for using a bad analogy, and you hit on a better one. You're right, the axioms, whether in economics or physics, must come from the empirical world. Given the axioms, you can then prove theorems, but of course the axioms might need tweaking---which can dramatically change the theorems. What I see in economics are cases where people implicitly accept particular axioms, and yet reject many of the consequences (i.e., theorems). It's as if they agree that Newton's law of gravitation is correct, but don't believe that two-body orbits are closed.<p>Though complex in general, there are aspects of human behavior that are consistent and quite simple, and serve as a solid foundation for a study of human action. (You probably recognize this as the Austrian approach of <i>praxeology</i>.) When I read the Austrian argument that any fixed amount of money-stuff (e.g., gold) is sufficient for exchange, I understand the axioms, follows the steps, and accept the conclusion. When I read the Keynesian arguments for the benefits of monetary expansion and "fiscal stimulus", I see---great clouds of fog. Their arguments are often too vague to untangle, but I can see that their conclusions (a) appear to be based on the same axioms I accept and (b) disagree with a theorem. Something doesn't add up.<p>In sum, the value of empiricism lies in finding the right axioms. If you discover "empirical evidence" that a theorem is wrong, you must either propose a change in the axioms or find a flaw in the proof. Contemporary economists often appear to do neither.<p>(The Card &#38; Krueger example is again instructive. If you raise the price of labor, people buy less of it, so minimum wage hikes must increase unemployment.  And yet, from  a contemporary NY Times article (<a href="http://bit.ly/5afSyk" rel="nofollow">http://bit.ly/5afSyk</a>), we find this:<p><pre><code>    They [Card &#38; Krueger] surveyed 400 fast food restaurants and found that
    those in New Jersey actually added 2.5 workers after the minimum wage went
    up. In Pennsylvania restaurants, meanwhile, payrolls shrank.

    Why should bosses hire more workers if it's more expensive to do so? The
    two economists speculate that any fast-food restaurant typically operates
    with a couple of vacancies it can't fill because it doesn't pay enough.

    "If you raise the minimum a little," said Professor Card, "teens who are
    sitting [at] home go out looking for jobs." 
</code></pre>
Apparently, these restaurant managers are too stupid to realize they're allowed to pay <i>above</i> the current minimum wage, thereby getting those lazy teens off their couches to fill the vacancies without a minimum wage hike. Truly, it boggles the mind.)