 In deliberating about what we ought, morally, to do, we also often attempt to figure out which considerations are most relevant. To take an issue mentioned above: Are surrogate motherhood contracts more akin to agreements with babysitters (clearly acceptable) or to agreements with prostitutes (not clearly so)? That is, which feature of surrogate motherhood is more relevant: that it involves a contract for child-care services or that it involves payment for the intimate use of the body? Both in such relatively novel cases and in more familiar ones, reasoning by analogy plays a large role in ordinary moral thinking. When this reasoning by analogy starts to become systematic – a social achievement that requires some historical stability and reflectiveness about what are taken to be moral norms – it begins to exploit comparison to cases that are “paradigmatic,” in the sense of being taken as settled. Within such a stable background, a system of casuistry can develop that lends some order to the appeal to analogous cases. To use an analogy: the availability of a widely accepted and systematic set of analogies and the availability of what are taken to be moral norms may stand to one another as chicken does to egg: each may be an indispensable moment in the genesis of the other. 