For a number of reasons, McCarthy argues that in Political Liberalism
...Rawls in effect cedes a certain primacy to the observer's perspective: the concern with stability in light of the fact of reasonable pluralism limits the scope of what may count as good reasons in matters of public justification. His understanding of the principle of moral motivation - a principle that could serve as the motto of Habermas's discourse ethics - supports this reading. The desire to be able to justify our actions to others on grounds that they could not reasonably reject is said to entail the restrictions on public reason we examined in Section II. "Since many doctrines are seen to be reasonable, those who insist, when fundamental political questions are at stake, on what they take as true but others do not, seem to others simply to insist on their own beliefs.... They impose their beliefs because, they say, their beliefs are true, and not because they are their beliefs. But this is a claim all equally could make; it is also a claim that cannot be made by anyone to citizens generally. So when we make such claims, others, who are themselves reasonable, must count us unreasonable" (p. 61), or even "sectarian" (p. 129) Rawls is specifically concerned here with the use of political power to repress comprehensive views. But the same general structure of argument underlies his restrictions on public reason: since many doctrines "are seen to be" reasonable, participants who "insist" in the public form on what they "take as true" but others do not are being "unreasonable." The political participant's desire to act on publicly justifiable grounds is refracted through the political observer's recognition of the fact of reasonable pluralism and emerges as a desire to avoid ideological controversy on fundamental matters, that is, to avoid being "unreasonable." In political discourse, this concept of the reasonable then displaces that of moral truth (or of validity in Habermas's sense): "Within a political conception of justice, we cannot define truth as given by the beliefs that would stand up even in an idealized consensus, however far extended.... Once we accept the fact that reasonable pluralism is a permanent condition of public culture under free institutions, the idea of the reasonable is more suitable as part of the basis of public justification" (p. 129).