  Contemporary legal theories define these two main interests in the nature of law in the following terms. First, we need to understand the general conditions that would render any putative norm legally valid. Is it, for example, just a matter of the source of the norm, such as its enactment by a particular political institution, or is it also a matter of the norm’s content? This is the general question about the conditions of legal validity. Second, there is the interest in the normative aspect of law. This philosophical interest is twofold: A complete philosophical account of the normativity of law comprises both an explanatory and a justificatory task. The explanatory task consists of an attempt to explain how legal norms can give rise to reasons for action, and what kinds of reasons are involved. The task of justification concerns the question of whether people ought to comply—morally speaking or all things considered—with law’s demands. In other words, it is the attempt to explain the moral legitimacy of law and the subjects’ reasons for complying with it. A theory about the nature of law, as opposed to critical theories of law, concentrates on the first of these two questions. It purports to explain what the normativity of law actually consists in. Some contemporary legal philosophers, however, doubt that these two aspects of the normativity of law can be separated. (We will return to this later.)