As I mentioned in my last posting on Allison's commentary, the work is intended to respond to Kant's Groundwork in both historical and philosophical respects. The first chapter of the commentary is ostensibly concerned to analyse the "Preface" to the Groundwork but it begins with remarks about the historical development of Kant's ethical views, going back as far as a letter Kant sent to Herder in 1767 where Kant appears to have first mentioned the very idea of a "metaphysics of morals" though here he is not, as Allison admits, very informative concerning how this area of study should be understood.
Allison dates Kant's "critical" turn in ethics to the same publication sometimes argued to be Kant's first "critical" work, namely the Inaugural Dissertation of 1770 though little is really said here about moral philosophy other than it should contain no empirical principles. Similarly, letters during the 1770s, when mention is made in them of moral philosophy, are not very expansive concerning Kant's positive approach to the area. Allison indicates a general belief that Kant may have been led to a kind of critical confrontation with moral thinking by means of the stimulus of Hume, as he was in theoretical philosophy, but little is advanced to make this point substantive. Allison also presents an extremely truncated conception of the ethical elements of the Critique of Pure Reason as only giving the basis for a view of what it is to be worthy of the "highest good", a view that is hardly adequate to the understanding of how this work connects to Kant's general ethics.
The historical section of Allison's first chapter has to thus be said to be rather thin and disappointing. By contrast, the philosophical analysis of the argument of the "Preface" perhaps produces more than one might have expected from Kant's text. As in the Inaugural Dissertation Kant here opens by indicating that principles of morality cannot be empirically derived or grounded although this does not mean they cannot be empirically applied. Later, in the Metaphysics of Morals, this latter comment is expanded to indicate that the conditions for fulfilling the laws of the "metaphysics of morals" is an important part of the latter's scope.
In the "Preface" Kant understands what is meant by a "metaphysics of morals" in a specific way, namely, that which belongs to pure or a priori moral philosophy. The claim to this effect is made at Ak. 4: 389 and analysis of this passage essentially provides Allison with his general view of the argument of the "Preface". Here Kant is argued to make three claims. The first is that a moral principle involves "absolute necessity", which is an expression Allison understands in a modalized rather than prescriptive sense. Viewing the claim in this way entails that the moral principle in question must be capable of holding in all possible worlds rather than being a principle without exceptions (as it would be on a prescriptive reading). Not only does Allison view the "absolute necessity thesis" in this modalized way, he also claims that it does not refer primarily to specific duties but to the underlying principle on which such duties would be based.
The second claim Allison indicates is made at Ak. 4: 389 is what he terms the "scope thesis" to the effect that a valid moral principle has to apply to all rational beings and not merely to human beings. Finally, the third claim in this passage is termed by Allison the "apriority thesis", a complicated multi-pronged claim. According to this last thesis the ground of moral obligation is found solely in a priori concepts of pure reason. This amounts to the view that the grounding of the principle that is the basis of all first-order moral principles is itself a priori and that searching for it must require a method that is akin to its object (and thus be itself a priori).
The "apriority thesis" has been subjected to some criticism, not least due to the point that finding the origin of a concept is not necessarily equivalent to finding its "seat". The "origin" of a concept would here refer to the ground of something's validity whereas its "seat" would refer to the place where the concept in question is located. So, you could hold, for example, that the "seat" of morality resides in innate ideas whilst its origin is in God's ends and hence have quite an important distinction here which, it could be argued, Kant's "apriority thesis" dogmatically neglects.
Allison considers this possible objection and suggests that its sharpest formulation could be found in the claim that the "Preface" offered insufficient reasons for thinking that the "origin" of the moral claim fits the apriority thesis. However, Allison indicates that he takes both the scope thesis and the absolute necessity thesis in a modalized form and that they reciprocally imply each other, not least because prescriptive versions of these theses could not justify the necessity of the principles that would be prescribed by the absolute necessity and scope theses. As this is so the question of the "origin" of the moral principle that meets the absolute necessity and scope theses becomes central to seeing the justification of the application to the moral principle of these theses. As Allison puts this point: "if we consider Kant's initial argument in the Preface for the necessity for moral theory of a pure, that is, a priori, moral philosophy, together with its extension in GMS 2, we find a two-part argument for the Sitz and Ursprung in pure reason of whatever could serve as the supreme principle of morality" (28).
The first part of this argument, which is given in the Preface, yields the conclusion that the "seat" of any moral principle must reside in concepts of pure reason. And the premises of this part of the argument are the absolute necessity and scope theses where these are understood without reference to modalization. The second part of the argument, by contrast, given later (in Groundwork II) presupposes that these principles have been modalized and argues from this presupposition to the view that the "origin" of any supreme principle of morality would lie in the universal concept of a rational being.
Allison also views the absolute necessity and scope theses to be found, albeit in unarticulated form, in the common or pre-philosophical, conception of morality. This claim, which requires careful consideration of the argument of the first part of the Groundwork on Allison's view, indicates how philosophically substantive he understands this first section to be.
The argument of the "Preface", however, after arguing for the view that moral theory needs a metaphysics of morals as a matter of necessity, advances next the claim that the metaphysics of morals is also important for moral practice. The basic reason for this claim (also made at Ak. 4: 389) is that without a metaphysics of morals conformity to the moral law is only contingent and fragile. So the claim here concerns the need for moral conduct to have a secure basis and is related to the further point that acting morally should involve acting for the sake of the moral law. In a sense, then, the question of how to ensure that one does act for the sake of the moral law is related to the question of how we show that the moral law is one that we necessarily should follow.
Allison's analysis of the "Preface" next discusses the reasons Kant gives for not having provided us in the Groundwork with a "critique", one of the reasons of which appears, however, to undercut the argument suggesting that a metaphysics of morals is important for moral practice. After all, Kant suggests that a critique in the practical domain is less important than in the speculative since in the practical area even the common understanding can be brought to a correct and complete view, a claim Allison traces back to Kant's Rousseauean conception of the "common man". The second reason Kant gives in this preface is to the effect that providing a practical critique would require articulating in addition the unity of theoretical and practical reason whereas the Groundwork has a more modest aim. This more modest aim is the third specific reason for failing to provide a critique since Kant gives the aim of the Groundwork as only being to provide a preliminary foundation for morals and not a system of morality itself. Interestingly, this indicates that the Groundwork is modest in two respects since it neither shows the unity of theoretical and practical reason or articulates a system of morality.
Finally, the distinction between analytic and synthetic procedures in the Groundwork is argued by Allison to be quite different from how the distinction is understood in the Prolegomena. The Groundwork is argued to practice a regressive argument that is also a form of conceptual analysis, a view that will be discussed in more detail later.