Rawls' third lecture on Kantian constructivism, as printed in The Journal of Philosophy, culminates the series he gave on this topic and addresses methodological contrasts between constructivism and some other views of moral theory. The central conception of Kantian constructivism has turned out to be the establishment of a connection between the first principles of justice and the conception of moral persons as possessed of freedom and equality. The connection is made by means of the procedure of construction by which rationally autonomous agents "subject to reasonable conditions" arrive at public principles. In concluding with a discussion of objectivity Rawls intends to secure the philosophical status of the constructivist procedure. This includes the basis for the view that principles of justice are best thought of as reasonable rather than true.
The first part of the third lecture consists in Rawls' summary of the work of Henry Sidgwick The Methods of Ethics. This work is the one that Rawls thinks of as being an "outstanding achievement" in moral theory. In making this claim Rawls also indicates what he takes "moral theory" to consist in: "the systematic and comparative study of moral conceptions" (554). Moral philosophy, by contrast, is wider since it takes its main question to be one of justification whether this is seen epistemologically or practically. Sidgwick's work is one Rawls thinks of as the "first truly academic work in moral theory" (554) which defines some of the comprehensive comparisons important to it. Sidgwick saw that moral theory was significant for moral philosophy but his work is seen as limited in at least two crucial ways by Rawls. The first key limitation in Sidgwick's approach according to Rawls is that he gives little attention to the conception of the person and the social role of morality. The reason for this is that Sidgwick assumed that a "method" of ethics is specified by first principles that aim at reaching true judgments. So justification is seen as a primarily epistemological problem.
The focus on truth does not only lead Sidgwick in this epistemic direction but it also leads him to restrict attention to first principles rather than to articulating views of the person and the social role of morality. Due to these elements of his view of "methods" of ethics Sidgwick does not articulate constructivism as a method. Sidgwick also failed to see that Kant presents us with a distinctive method of ethics since Sidgwick understood the categorical imperative as equivalent to a principle of equity that requires treating persons similarly in similar situations. Because Kant's view is not regarded as providing us with a "method" of ethics Sidgwick is left counting only egoism, intuitionism and utilitarianism as real methods says Rawls. In making this statement Rawls is wrong since he leaves out Sidgwick's view of common sense morality, something of cardinal significance in The Methods of Ethics. In claiming also simply that Sidgwick "favours" the utilitarian method Rawls also neglects here the large scope Sidgwick subsequently gives to intuitionist elements in his treatment. But Rawls is certainly right to claim that Kant is given no sustained analysis by Sidgwick who spends more time on replying to Kant's view of freedom than he does to any clear account of the central elements of Kant's moral theory.
After opening with this discussion of Sidgwick Rawls moves on to a contrast between Kantian constructivism as conceived in these lectures with rational intuitionism. Rational intuitionism is presented here as grounded on two views. These are, firstly, that the central moral concepts are not analyzable in nonmoral terms and, secondly, that first principles of morals are self-evident. So it follows from these claims that agreement in judgment would be based upon recognition of self-evident truths about good reasons with these reasons fixed by a moral order that is independent of and prior to our conception of the person. In characterising intuitionism in this way Rawls sees it as favouring a priority of the good over the right and capturing this priority in terms of the moral order being prior to the person. The contents of the doctrine that ensue can be varied for intuitionists and now he outlines a sense in which utilitarian views could even be said to follow from them.
The point of discussing intuitionism is to indicate that heteronomous conceptions of morality need not be naturalistic. And heteronomy is now presented by Rawls as the claim that the basic truths of morality are independent of (or justifiable without reference to) a conception of the person. A Kantian claim, which includes the notion of synthetic a priori judgments, is, by contrast, one that requires practical reason to include central formulations of the person. So first principles are related to this sense of the person with the idea of it being embedded in the notion of practical reason in some way. By contrast the conception of the person for an intuitionist is much more sparse.
If the view of the person is one of the means by which intuitionism can be contrasted with Kantian constructivism the other that Rawls considers concerns the limitations of moral deliberations. Constructivists, as viewed by Rawls, do not view the powers of reflection and judgment involved in moral deliberation as fixed in any absolute way. Rather they are reflections of the public culture to which they belong. This is why justice as fairness can be presented through the device of the original position as arriving at public agreements. The conception of justice involved here is one that relates to the framework of deliberation that produces it rather than pre-existing such deliberation. The limitations of such deliberation are reflected also in the narrow arena within which clear agreement is defined as possible, for example, within justice as fairness, the basic structure. Requirements that relate to the subject of justice are also built into the scheme of justice as fairness such as the ability of principles to meet criteria of publicity. In order to meet such requirements principles cannot be above certain levels of complexity. Certain facts are thus rendered irrelevant in consideration of the constraints of the procedure adopted.
In principle also the procedure of constructivism requires as well priority rules of certain sorts such as the priority of justice over efficiency or that of the first principle of justice over the second. The plausibility of these priority rules enables ways of dealing with the complexity of the many prima facie rules that are generally stated. The idea of the basic structure also plays the special role of defining what background justice is understood to be like. Comparisons of what outcomes are better or worse are also enabled by the reference to the notion of primary goods. This latter notion requires some sense of the agents who are to be party to the agreement that can emerge from the original position.
Alongside these constraints of a constructivist procedure is the abandonment of moral truth as the basic pursuit of moral doctrines. No specific principles are assumed to be correct prior to the initiation of the procedure of construction and no moral facts are taken to hold separately from this procedure. The first principles single out what facts would count as reasons of justice. So the procedure of construction of the original position determines what "facts" are to be counted. Constructivism also requires no specific doctrine of truth.
The main ideals of justice as fairness are found in the "model-conceptions" of the well ordered society and the moral person. The original position enables representation of the Reasonable and the Rational and from its constraints the principles of justice emerge for the citizens of a well ordered society. So the procedure of construction has an intimate link to the way that principles of justice appear to be embedded in conditions of our life by means of reflection on that life. These conditions are what Rawls described as the circumstances of justice and consideration of these circumstances as constrained by the sense of what is Reasonable produces, in relation to our "model conceptions" the sense of the principles of justice.
The Kantian view, as seen by Rawls, addressees the public culture of a democratic society in order to bring to awareness a conception of the person and social cooperation that is implicit within this culture. This does not mean our society is well ordered since the public conception of justice is disputed within it. But the procedure of construction is one that has to be congruent with elements of our existing culture in such a way that it can meet criteria of public justification. First principles that are presented by constructivism are not "true" but reasonable and what is rather "true" are statements about how derivative principles follow from first principles.
The notion of rational intuition is one that Rawls wishes to argue is an unnecessary one for the attainment of the goal of moral philosophy. Objectivity does not require the standpoint of the universe as Sidgwick suggests. It requires instead a social point of view that is publicly shared or would be in a well ordered society. Such a point of view is what is required within a basic structure and which models the conception of the person within such a structure. The person should be seen not in epistemic but in practical terms, that is, as involved in social cooperation. The means by which this determination of the person operates is through the avenue of potential agreement on public conceptions. Such agreement emerges from a view of the person as possessed of moral powers that articulate a notion of autonomous reflection. It is by these means Rawls hopes to articulate a way past the impasse in contemporary societies about the appropriate way of viewing justice.