Economic analysis is itself value-free, but in practice it encourages a cosmopolitan interest in natural equality. Many economic models, of course, assume that all individuals are motivated by rational self-interest or some variant thereof; even the so-called behavioral theories tweak only the fringes of a basically common, rational understanding of people. The crucial implication is this: If you treat all individuals as fundamentally the same in your theoretical constructs, it would be odd to insist that the law should suddenly start treating them differently.
Cowen concludes by exploring a modern-day application of this putatively egalitarian core:
A distressingly large portion of the debate in many countries analyzes the effects of higher immigration on domestic citizens alone and seeks to restrict immigration to protect a national culture or existing economic interests. The obvious but too-often-underemphasized reality is that immigration is a significant gain for most people who move to a new country.