Is there any mode of reasoning proper to or exclusive of legal reasoning? Alexander and Sherwin argue in this provocative book that the answer to this question should be negative, contrary to what, as they understand, has been the position defended by the majority of legal theoreticians. According to Alexander and Sherwin, if legal reasoning is part of practical reasoning, there is nothing particular to it and legal training is not required for it (pp. 3, 104, 130, 204). Moreover, legal reasoning is nothing but “ordinary reasoning applied to legal problems” and as such it does not entail any special or particular mode of reasoning different from those that are available to every “actor that has to decide what to do” (p. 3). Thus, the methods available in legal reasoning can only be of three kinds: i) open-ended moral reasoning; ii) empirical reasoning; and, iii) deductive reasoning from authoritative rules (ibid.). Something similar is stated regarding interpretation of posited law. As in ordinary interpretation of demands and requests, “interpretation of legal rules is a search for the rule maker's intended meaning” (p. 190). The argument of the book is structured in three parts. After the conceptual foundations of the analysis are settled (part one), the demystification process is developed. First, against those theories that defend special methods of reasoning (i.e. analogical reasoning and legal principles) available only to those that have the required technical legal knowledge (part two); and then, against those who defend a special method of interpretation of posited law (part three). At the end of the demystifying enterprise we are left face to face with the “basic dilemma of law” offered as a conclusion, i.e. that there is no “middle position between unconstrained reasoning and unreasoned submission to authority” (p. 235).

Though Alexander and Sherwin affirm that “nothing in [their] analysis of legal reasoning requires an answer to the jurisprudential question of what counts as law”, much of their arguments rest in a continuous contrast against an ideal criterion of what should count as law (p. 24). According to their analysis of the law and its function, legal authorities are established by a community to settle moral controversies by rational deliberation (p. 10). These authorities will not be able to decide on each and every moral controversy that would arise within a community, so they address in advance these problems of controversy and uncertainty by establishing “serious rules” (pp. 11, 13, 27). Some of the characteristics of these rules are that they are posited by human beings, they establish general prescriptions, and that its subjects need not consult the rules' purposes (pp. 10–2). However, in some cases, due to epistemological or empirical constraints, authorities will prefer to promulgate abstract legal standards. These standards should be understood as “implicit delegation[s] of rule-making authority” (p. 14). If these are the type of standards that we will find in a legal system, the analysis of legal reasoning is mainly an examination of “how judges respond to posited law and how they distinguish between reasoning from posited law and reasoning in the absence of posited law” (p. 25). Within this conception of common law “courts function in two ways: they reason deductively from rules posited by others; or they posit law, relying on moral and empirical judgement, as any lawmaker does” (pp. 25–6).

Once that judges are recognised as authorities with adjudicative and legislative powers, the only possible modes of reasoning available to them in the common law are natural and deductive reasoning (p. 39). Natural reasoning recognise that judges use moral and empirical reasoning when acting as legislators (p. 32). The former is understood under Rawls' method of reflective equilibrium while the latter is applied when the consequences of a decision are relevant (pp. 32–4). In this model past decisions by previous judges are not authoritative but part of the facts (as generating certain expectations) that judges should have in consideration when reasoning (p. 39). The alternative model is the rule model. The main difference between this model and the natural is that judges consider previous judicial decisions as authoritative rules. Thus the method of reasoning available to judges is purely deductive reasoning. On the other hand, when no rule (previous decision) exists, the natural model is available (p. 40).

When opting for one of these models as the ideal one for the common law, the function of the law becomes the relevant criterion for the decision. That is why Alexander and Sherwin prefer the rule model based on the idea that judges working as law makers “can increase the level of coordination within the community” even if they lack special expertise (p. 45). The final test in favour of this model is an empirical one. The rule model will outweigh the natural model if the results of the first diminish the amount of moral errors of the second (pp. 49, 99, 107).

It is not necessary for the purposes of this review to analyse the details of the arguments displayed by the authors to demonstrate why analogical reasoning and legal principles are not reasoning methods (pp. 64–104). Enough is to say that these arguments are built on logical and analytical lines and they are oriented to show how legal principles and analogical processes cannot perform the functions they are supposed to; the first, “impose no […] constraint on judicial reasoning”, while the latter, “rest in fact on natural or deductive reasoning” (p. 104).

Considering the kind of arguments developed in the book it is not surprising that Alexander and Sherwin understand that there is nothing particular to the legal interpretation of authoritative rules promulgated by law makers that could be taught in a law school (p. 131). In their view “[p]osited laws are nothing more or less than communications from lawmakers to others regarding what the lawmakers have determined the others should do” -just as a “letter written by Mom requ[iring something] or a note signed by your two kids asking you to rent a movie”-, so “interpretation in law as in life is a search for speaker's meaning” (pp. 131, 32, 33). And here as in the rest of the book, the reason for this approach rests on the “objective of authoritative settlement [that] dictates that the only meaning that should count and that should guide legal interpretation is the meaning the lawmaker intended to convey through his rule” (p. 141).

In general terms the book accomplishes its function of introducing students of law, philosophy or political science to the main discussions in (American) legal reasoning. However there are two weaknesses of the book that could bias its introductory character. The first one is that the discussion is excessively centred in the discourse of American jurisprudence. The second problem derives from the first. An important deficit of the book is that its authors did not engage with the work of some of the most important theoreticians in legal reasoning, who defend opposite ideas about the claims that have been raised in this review: i) that legal reasoning is not related with a theory of law; and, ii) that the demystification of legal reasoning leads us to a dead end in which we have to choose between pure moral reasoning or rule formalism. Neil MacCormick's Legal Reasoning and Legal Theory (Oxford 1978) and Rhetoric and the Rule of Law (Oxford 2005), and Robert Alexy's A Theory of Legal Argumentation (Oxford 1989) are important pieces that are not considered in the analysis.