Dworkin’s insight, brought out in his critique of pragmatism, is that a legal conclusion cannot supersede if the proposition of law is merely the same type of judgment as the conclusion of moral reasoning. Although Dworkin does not use Joseph Raz’s terminology of first- and second-order reasons, he appears to have something like that in mind when he defends the obligations arising from membership in a political community. Considerations such as justice play a role in the reasoning process that determines the obligations community members have, but they are not conclusive. A legitimate conclusion of law depends on showing that it is the best constructive interpretation of the community’s political practices from the evaluative standpoint of political morality. A legitimate demand comes to its subject in the first-person plural: we have determined that we have a right to X and an obligation to Y. The law is therefore comprehensively intertwined with democratic self-governance. It requires obedience because it is a scheme of rights and duties that we, as a community, share. It is a commitment to treat one another with respect and as equals, even when we disagree. Legitimacy demands that we offer each other principled reasons for the use of coercive state power.
The idea that a norm that does not conform to the natural law cannot be legally valid is the defining thesis of conceptual naturalism. As William Blackstone describes the thesis, "This law of nature, being co-eval with mankind and dictated by God himself, is of course superior in obligation to any other. It is binding over all the globe, in all countries, and at all times: no human laws are of any validity, if contrary to this; and such of them as are valid derive all their force, and all their authority, mediately or immediately, from this original" (1979, 41). In this passage, Blackstone articulates the two claims that constitute the theoretical core of conceptual naturalism: 1) there can be no legally valid standards that conflict with the natural law; and 2) all valid laws derive what force and authority they have from the natural law.