Rawls’ Overarching Framework Rawls reworks his political liberalism in Political Liberalism by beginning from the ‘fact of reasonable pluralism’. This reasonable pluralism entails that citizens, understood as being free and equal, are now the foundation of a theory of justice as fairness. Hence, Rawls characterizes persons:
…the person is seen rather as a free and equal citizen, the political person of a modern democracy with the political rights and duties of citizenship, and standing in a political relation with other citizens… citizens are to conduct their public political discussions of constitutional essentials and matters of basic justice within the framework of what each sincerely regards as a reasonable political conception of justice, a conception that expresses political values that others as free and equal also might reasonable be expected reasonable to endorse.
The political conception of the person as free and equal under-girds a political conception of justice as fairness, the two Rawlsian principles of justice, and the strong commitment to public reason. Public reason becomes that which protects the freedom and equality of pluralistic citizens – it is a set of neutral reasons, political reasons, that reasonable citizens can give which do not depend on any particular comprehensive doctrine. Hence the name that can be applied to this is ‘neutral liberalism’. It is intended as neutral precisely because of reasonable pluralism – a comprehensive liberalism would itself be a comprehensive doctrine, and Rawls seeks to avoid this option.
If Rawls is correct, and his project works, then all reasonable holders of comprehensive doctrines (including comprehensive liberals, traditional Roman Catholics, Libertarians, Muslims, etc) should be able to reasonably endorse a purely “political liberalism” without compromising their fundamental moral, religious, and philosophical commitments. It should not be logically possible for a reasonable comprehensive doctrine to reasonably deny the dictates of liberal public reason. If they are reasonable the various comprehensive doctrines – especially including the religious ones – should be able to be a part of an overlapping consensus of reasonable views, ensuring social harmony. This social harmony, brought about by the exercise of public reason for the sake of political persons, is protected and grounded by reciprocity – only those claims in the public arena are reasonable which could be expected to be reasonably held by all other reasonable citizens.
The Putative Problem The claim of the putative problem is straightforward: no serious religious person, nor anyone who takes the tradition of natural law seriously, such as a traditional Roman Catholic, can accept Rawls’ public reason. Such would involve the denial of his or her own comprehensive doctrine. It must involve the denial of their comprehensive doctrine, since it is logically possible that there be (e.g. Catholicism or natural law) a comprehensive doctrine that, for internal reasons, cannot endorse the dictates of public reason – and yet that doctrine is both rational and reasonable. I say for ‘internal reasons’ since the reasons why they must deny the dictates of liberal public reason stem not from any haphazardly held moral doctrine, but for reasons constitutive of the comprehensive doctrine as a whole. That is, they could not be the comprehensive doctrine that they are and not hold these positions contrary to liberal public reason. To hold to the comprehensive doctrine and to affirm liberal public reason would be to compromise the integrity of the comprehensive doctrine. Since there is indeedsuch a comprehensive doctrine Rawls must deny that they are reasonable and not merely to the extent that they disagree with public reason – otherwise his liberalism is itself a comprehensive doctrine. Rawls does, or at least is forced to, admit that they are unreasonable – hence the putative problem.
Rawls cannot allow his theory of political liberalism to be a liberal comprehensive doctrine, for that would admit that it is not freestanding. But since it is obvious that Roman Catholicism and natural law are reasonable comprehensive doctrines, despite their internal inability to affirm liberal public reason, Rawls must be wrong in regards to their unreasonableness – and hence his liberalism must itself be a comprehensive doctrine. The only method to demonstrate a reasonable comprehensive doctrine to be internally unreasonable would be to directly attack those internal reasons. Such would involve demonstrating exactly why the positions held by that comprehensive doctrine are false. Neutral political liberalism, however, insofar as it is freestanding, is not permitted to directly attack the internal workings of a reasonable comprehensive doctrine. As such, then, his concept of public reason – the foundation of a political conception of justice whereby an overarching consensus is met and the two principles of justice are affirmed – is not a freestanding one. If it is not freestanding it must stand upon a metaphysic and conception of the good – i.e. it must be a comprehensive doctrine all its own. In that case, given that it is a comprehensive doctrine all of its own, if it contradicts the internal workings of another comprehensive doctrine, or relegates another comprehensive doctrines’ reasons to the private sphere, then it does so illegitimately. It does so, on the grounds of Rawls’ own theory. According to Rawls’ own theory it would be an illegitimate coercion for one comprehensive doctrine to be enforced as the public reason; that would deny the fact of reasonable pluralism, a matter that any acceptable theory of justice must preserve. Yet this is precisely what political liberalism, as a comprehensive doctrine, ends up doing. And so by his accounts his own theory should not be an acceptable theory of justice.
The putative problem takes the following formal definition:
(PP) – Liberal public reason cannot be accepted by (at least some) reasonable comprehensive doctrines due to reasons internal, and constitutive, of them. Therefore Rawls’ theory of political justice is internally contradicted and is not an acceptable theory of justice.
The argument for (PP) takes the following logical form:
1. If political liberalism (PL) is an acceptable theory of justice, then it is just.
2. If PL is just (according to Rawls’ own criteria), then it is freestanding (FS).
3. If (PL) is (FS), then it does not appeal to any comprehensive doctrine (CD).
4. If (PL) does not to appeal to any (CD), then it does not deny any reasonable (CD) to be reasonable for reasons internal to that (CD).
5. If (PL) does not deny any reasonable (CD) to be reasonable for reasons internal to that (CD), then it must not be logically possible for there to be a reasonable (CD) that cannot affirm the dictates of liberal public reason (PR).
6. If it is not logically possible that there is a reasonable (CD) that cannot affirm (PR), then (PR) is correct.
7. If (PR) is correct, then any (all) reasonable (CD) must be able to endorse the conclusions of (PR).
8. If any reasonable (CD) can endorse the conclusions of (PR), then there is no reasonable (CD) that cannot endorse the conclusions of (PR).
9. There is a reasonable (CD) that cannot endorse the conclusions of (PR) – e.g. Roman Catholicism or natural law.
10. \ Not all reasonable (CD) can endorse the conclusions of (PR) – modus tollens, 9 + 8.
11. \ It is not the case that (PR) is correct – modus tollens,, 10 + 7.
12. \ It is not the case that it is not logically possible that there is a reasonable (CD) that cannot affirm (PR). (I.e. it is logically possible) – modus tollens, 11 + 6.
13. \ It is not the case that (PL) does not deny any reasonable (CD) to be reasonable for reasons internal to that (CD). (I.e. it does deny them, for reasons internal to them) – modus tollens, 12 + 5.
14. \ It is not the case that (PL) does not to appeal to any (CD). (I.e. it does appeal to a comprehensive doctrine) – modus tollens, 13 + 4.
15. \ It is not the case that (PL) is (FS); i.e. political liberalism is not freestanding –modus tollens, 14 + 3.
16. \ It is not the case that (PL) is just (according to Rawls’ own criteria) – modus tollens, 15 + 2.
17. \ It is not the case that political liberalism is an acceptable theory of justice (given Rawls’ own criteria) – modus tollens, 16 + 1.
18. \ Rawls’ own criteria, coupled with premise (9), entails that political liberalism is a self-referentially self-contradictory theory of justice.
19. \ (PP).
What the argument for (PP) demonstrates is that Rawls’ theory of justice relies upon metaphysics and morality – despite Rawls’ appeals to the contrary. It turns out that this metaphysics and morality, however, is obscure. Given that Rawls’ own theory denies that this reliance is the case it cannot make clear what it amounts to, and so is necessarily obscure. This is what Peter Berkowitz has called the “liberal faith”: liberalism must rely on a metaphysics and morality that it cannot admit. For this reason the religious person or the natural law theorist, who has a metaphysic and a morality clearly defined and operating within a rational tradition, ought not be motivated to accept the criteria of liberal public reason and, hence, political liberalism.
 For a helpful summary of Rawls’ reworked political framework, see Robert George, “Public Reason and Public Conflict: Abortion and Homosexuality”. Yale Law Journal 106 (1997): 2477-2481. See also Samuel Freeman, “John Rawls – An Overview”. In The Cambridge Companion to Rawls, Samuel Freeman (ed). New York: Cambridge University Press, (2003), 1-61.
 John Rawls, Political Liberalism, xl-xlii.
 Ibid, xliii, xlviii.
 Rawls takes a ‘comprehensive doctrine’ to be any moral, religious, or philosophical set of doctrines, held over a complete life, that constitutes a vision of what is good for a person, over a complete life.
 Ibid, xlviii. See also 301-302, 304.
 As opposed to a “comprehensive liberalism”.
 To demonstrate this point, consider Thomas Nagel’s comments on Rawls’ reasons for holding to public reason: “He wants a justification for liberty and pluralism that does not rely on the individualistic system of values so many liberals share. Political liberalism should be compatible with religious orthodoxy. Rawls wants this because, when it comes to constitutional essentials, it is insufficiently respectful toward those many members of a liberally governed society who do not share those comprehensively individualistic values to justify the institutions under which we all must live, and the rights which those institutions guarantee, by reference to grounds those individuals cannot reasonably be expected to accept.” “Rawls and Liberalism”. In The Cambridge Companion to Rawls, Samuel Freeman (ed). New York: Cambridge University Press, (2003), 75.
 Ibid, xlv-xlvi.
 For a detailed criticism of Rawls’ criterion of reciprocity, see Robert George, “Public Reason and Public Conflict: Abortion and Homosexuality”. For a helpful summary of public reason, see Samuel Freeman, “John Rawls – An Overview”. In The Cambridge Companion to Rawls, Samuel Freeman (ed). New York: Cambridge University Press, (2003), 37-44.
 This is not to say that these groups are the only groups that cannot accept liberal public reason. Any comprehensive doctrine of similar structure will have the same concerns.
 See Rawls’ discussion of unreasonable comprehensive doctrines in Political Liberalism, 243n32.
 See Robert George, “Public Morality, Public Reason”. First Things November (2006): 23
 See Peter Berkowitz, “John Rawls and the Liberal Faith”, Wilson Quarterly (Spring 2002): 66.
 Ibid, 68.