Cultural Diversity and the Shared Premises Requirement


The shared premises requirement for political debates becomes challenging when citizens of diverse cultural backgrounds, religious faiths and political convictions come to live together. Since citizens would naturally rely on all their dearly held views, beliefs and values, the shared premises requirement might be seen as a considerable burden under the condition of pluralism. The danger is that not only cultural minorities, but also persons of faith might feel alienated by such a requirement for political debates in a liberal polity.

In what follows, we would like to go back to an early stage of the debate on the shared premises requirement and reconsider an objection against it as formulated by Michael J. Perry. Perry, in an article from 1989 and a book from 1991, criticizes the requirement as elaborated in the work of Bruce Ackerman and Thomas Nagel, two prominent liberal proponents of the requirement. Even though Perry has published extensively on this and related topics, and his views have developed and changed over the years1, the formulation of his critique seems as poignant and engaging as ever, and highlights some crucial problems regarding the requirement. It therefore seems worthwhile to get back to this early stage of the debate and reconsider Perry’s forceful critique. We will try to show why Perry’s critique is problematic, and why some qualified form of the shared premises requirement in political debate does not overly burden cultural minorities or people of faith, and thus helps to reach a legitimate and stable polity.

Perry’s rejection of the shared premises requirement

Bruce Ackerman, in his article “Why Dialogue?” from 19892, introduces a principle of conversational restraint in his attempt to conceptualize neutral and fair political justification. (Ackerman 1989, 16-17) According to Ackerman, in a political conversation or dialogue, citizens should avoid normative premises that are not shared, and instead search for reasons that all sides find acceptable. Leaving aside the moral ideals we disagree about, we can focus instead on political grounds that all participants find acceptable. This requirement, as Ackerman points out, does not apply to the questions citizens may ask – since this would merely foreclose the search for commonly acceptable political solutions – but only to the answers they may legitimately give to each others’ questions. (Ackerman 1989, 17-18)

In his article “Moral Conflict and Political Legitimacy” (1987), Thomas Nagel proposes conditions that political justification must satisfy in order to be impartial and fair. To reach impartial political justification, reasons should only be offered and rejected on the basis of “common critical rationality” and “considerations of evidence that can be shared” (Nagel 1987, 232). In other words, “it must be possible to present to others the basis of your own beliefs, so that once you have done so, they have what you have, and can arrive at a judgment on the same basis” (ibid., emphasis in the original). This excludes our personal faith or revelations as reasons in political justification, since they do not give to others what we have. Instead, what is needed for others to arrive at what we have are evidence or arguments. (Ibid.)

Against both Ackerman’s and Nagel’s version of the shared premises requirement, Perry holds that they have overly demanding consequences for religious persons. This is so because a religious person cannot refer to her most dearly held religious beliefs in a political debate with a non-religious person. Since this might severely affect the religious person’s moral and political integrity, this objections can be dubbed integrity objection. Note, furthermore, that by the notion of religious beliefs we do not mean to imply any epistemological view on what beliefs – and more specifically religious beliefs – are, or whether there are such things as beliefs in the first place. Neither is it necessary to ascribe any such epistemological view to Perry himself regarding his critique of Ackerman and Perry, or so it seems. By a person’s reference to religious beliefs in political debate we, and arguably Perry as well, simply mean her use of religious language in such debates. Regarding Christians and other theists this would, for instance, concern God-talk and references to the holy scriptures.

Perry’s critique is most strikingly formulated in an imagined political debate between himself, a religious person, and Ackerman, a non-religious person. In a political debate between Perry and Ackerman, the proportion of Ackerman’s relevant beliefs that Perry would share would be larger than the proportion of Perry’s relevant beliefs that Ackerman would share. In other words, Ackerman would be able to rely on a larger part of his web of beliefs in a political debate, whereas Perry would be able to rely merely on some strands of his web. This is the case because Perry’s relevant beliefs include all his religious beliefs – beliefs that his non-religious counterpart does not have. These religious beliefs are, according to Perry, relevant to most of his views on fundamental political-moral issues. This situation would, therefore, leave him at a serious disadvantage in a discussion with Ackerman, because Ackerman could rely on most of his relevant beliefs, whereas he could rely merely on some of his relevant beliefs. (Perry 1989, 484; Perry 1990, 10)

Furthermore, Perry is disadvantaged because Ackerman might get to rely on his most important relevant beliefs, whereas Perry would not be able to rely on his most important relevant beliefs: his religious ones. This is necessarily so because religious beliefs cannot be shared between a religious and a non-religious person. In the political debate with Ackerman, Perry is thus forced – following the shared premises requirement – to leave his most dearly held beliefs aside and to rely only on those strands of his web of beliefs “approved (‘shared’) by Ackerman” (Perry 1989, 484; Perry 1990, 10). Perry’s integrity in political debate is thus violated in a second way, because he is forced to bracket his most important beliefs.

Perry criticizes Nagel’s implicit version of the shared premises requirement on the same ground. By confining political justification to “common critical rationality” (Nagel 1987, 232), i.e. to whatever beliefs are commonly accepted, Nagel’s view also privileges some beliefs over others, namely those shared and accepted as authoritative. (Perry 1989, 487; Perry 1990, 14) In a debate with Perry, Nagel’s non-religious beliefs would therefore be privileged over Perry’s religious beliefs because, again, religious beliefs cannot possibly be shared between Perry and Nagel. When debating with Nagel, Perry would get to rely merely on some of his relevant beliefs – not including the most important ones – whereas Nagel might rely on most of his relevant beliefs – including the most important ones. (Perry 1989, 487; Perry 1990, 14-15)

To make things even grimmer, and to cast a different light on Perry’s critique, let us briefly consider Steven D. Smith’s rejection of the shared premises requirement. In his words, the “common denominator ploy” is fraudulent. He asks us to suppose that a father and his daughter are discussing what to have for dinner. The daughter prefers having just dessert, while her father suggests that it would be better to have a full meal, and then dessert. The daughter reasons as follows: “We disagree about a lot of things. But there is one thing we agree on. We both want dessert. So let’s have just dessert.” According to Smith, the shared premises requirement works in a similar fashion, and is thus as unpersuasive as the daughter’s reasoning. (Smith 1989)

Objections against Perry’s view

1. However, Perry’s argument is problematic, or so we will argue. Let us first consider Perry’s critique that a religious person will be able to rely on merely some of her relevant beliefs, while a non-religious person can rely on most of her relevant beliefs. This seems to be a consequence of the requirement because the religious person’s web of beliefs contains strands that the non-religious person does not have. In presenting the case as he does, however, Perry seems to suggest that it is mainly or even only religious beliefs that are disadvantaged.

But what is about Ackerman’s and Nagel’s views that are not shared? After all, we might think of relevant beliefs of a non-religious person that can never be shared with a religious person too. Consider, for instance, the Marxist and secular view that religion is the opiate of the masses. This belief could not possibly be shared by a religious person, just as the belief “God exists” could not possibly be shared by a true Marxist. Marxists, just as religious persons, could more often than not – when discussing with religious persons, capitalists, libertarians etc. – rely only on some of their relevant beliefs.

Perry seems to base his argument on inadequate assumptions about secular webs of beliefs. These inadequate assumptions lead to an inadequate view on the shared premises requirement. Thus, it is not biased against religious beliefs in particular, but against controversial views in general, as the debate between the Marxist and the religious person indicates. The requirement does not favor secular views over religious ones, but uncontroversial over controversial ones.

Thus, if we interpret Perry’s claim as holding that secular views are privileged over religious ones, then Perry’s view is inadequate. However, Perry might still hold on to the weaker claim that, even if the shared premises requirement is not discriminating against religious views in particular, the fact that noncontroversial views are favored over controversial ones has still disadvantageous consequences for religious views. The disadvantageous consequences are due to the fact that religious views necessarily are controversial in a plural society, whereas a secular citizens’ political views may more easily and fully be founded on shared, uncontroversial beliefs.

According to this weaker claim, shared values such as peace, liberty, security or human well-being may be sufficient to ground many of a non-religious person’s political-normative views. A religious person’s political-normative views, on the other hand, will also be grounded on her religious beliefs. The shared premises requirement seems to bear the consequence that the religious person’s political-normative views, along with the religious beliefs on which they are based, are excluded from political debate. We therefore still face the objection that the shared premises requirement has overly burdensome consequences for religious persons, but not for secular ones. The same might hold for members of a cultural minority that base their political-normative views on their cultural traditions.

The weaker claim assumes, however, that normative views based on religious beliefs, or cultural traditions, are not overdetermined. That is, it assumes that normative views of a religious person are uniquely based on religious beliefs, and that there is no possibility to reach similar normative views on different paths or grounds. As the parable of the good Samaritan indicates, this is an inadequate assumption about the nature of normative views. The biblical story of the Samaritan might ground the normative belief of a religious person that we should help those in need, even if they are strangers and we do not like them. This normative belief, however, is not only acceptable to the religious person. The moral point of the biblical story can be translated in non-religious terms, and will also appeal to non-religious persons. This is so precisely because the moral point of the biblical story about the Samaritan, as arguably many other religious normative beliefs, is overdetermined and also reachable on other than religious grounds.

This view suggests that a religious and non-religious person might often have more in common than it seems at first glance. It also suggests that the shared premises requirement does not hinder religious persons to draw on their religious normative views – as long as these religious normative views also have grounds that are accessible and acceptable to non-religious persons. Thus, if we assume that much religious normative views are overdetermined, then the shared premises requirement does not preclude religious persons from drawing on much of their normative beliefs, and it would not have the overly burdensome consequences that Perry suggests.

In a response to Smith’s critique of the shared premises requirement, we might rely on a similar line of argument. Thus, the shared premises requirement cannot be rejected on the same grounds as the daughter’s reasoning in Smith’s dinner story. The daughter assumes that if her father wants to have both a full meal and a dessert, then he wants, firstly, a full meal and, secondly, a dessert. But this is a mistake. The dessert is valuable for the father only if he gets the full meal.3 In other words, the daughter makes the mistake to assume that if the dessert is part of the meal, then when the father values the meal, he also must value the dessert independent of the meal. However, the father only values the dessert insofar as it is part of the meal.4 The case of the shared premises requirement is different. Reconsider briefly the Samaritan example. It is a mistake to assume that if a non-religious person values the belief that we should help those in need, then she also should value the Samaritan story. The acceptance of the belief that we should help those in need simply does not depend on the acceptance of the Samaritan story. This is so because the belief that we should help those in need is overdetermined, and accessible and acceptable on religious as well as non-religious grounds. It is quite plausible that people’s shared beliefs are valuable for them even when the beliefs are not presented together with their personal, for instance religious, normative views.

The shared premises requirement in a political debate only becomes relevant when religious normative views cannot be understood and accepted by the non-religious person, or when there are beliefs that are not overdetermined. In the first case, further deliberation might help to sort out the common normative grounds. In the second case, both sides would indeed have to accept that the beliefs in question – whether religious or not – are controversial and should therefore be excluded from political debate.

2. Let us now consider the second line of Perry’s critique, namely that the shared premises requirement might impose to a religious person to bracket her religious beliefs that are most important to her, and maybe even constitutive of her identity. Such an imposition would still have overly demanding consequences for religious persons. To meet this objection, consider an inclusive5 or wide6 reading of the shared premises requirement, according to which a religious person is free to refer to her most important religious beliefs as long as she supports her arguments also with largely shared premises.

Consider the shared view among a religious and non-religious person that the state should support the poor. For the religious person this belief is linked to, or based on, another belief that is most important to her, namely that charity through state institutions is good because a divine spirit, through a holy scripture, says so. The non-religious person believes that the state should help the poor because of her most important belief that all persons have a basic right to welfare, a right that imposes certain duties on states. In a discussion between the religious and non-religious person, they would agree on the shared premise that the state should support the poor, but would have most different reasons why they accept this shared belief. According to the inclusive reading of the shared premises requirement, both persons could fully rely on their most important beliefs, since they also present the shared premise that the state should help the poor.

What if the interpretation of the shared belief by the religious person is colored by a controversial religious belief, for instance when for the religious person “poor” means “deserving poor” on scriptural grounds? Given the shared belief “the state should help the poor”, the shared premises requirement would still allow both persons to present their controversial stories behind the shared belief – no matter how controversial they are. Even though such a scenario might seem strange, they are very well imaginable and practicable, as political alliances between parties of the far right and the far left on certain topics, such as anti-globalization, indicate.

3. Finally, let us consider why not even an exclusive interpretation of the shared premises requirement – i.e. the view that persons engaging in political debates should refer only to normative premises that are widely shared – is overly burdening regarding religious persons. First of all, and as indicated earlier, all kinds of arguments that are based on contestable normative premises, not just religious ones, would be banned.7 Indeed, the only group that would not have to exclude certain views from political debate would consist of persons whose most important beliefs are shared by all others. It is therefore hard to see why religious persons would be especially burdened even in the exclusive reading of the shared premises requirement.

Another reason why the shared premises requirement is not especially burdening regarding religious persons even in an exclusive reading is that religious beliefs might not be that relevant in many political debates as critics of the shared premises requirement seem to suggest. If religious beliefs are irrelevant, a civic duty not to use religious premises has no practical relevance, and therefore does not disadvantage religious persons. This is the case in a least some political debates, for instance regarding details of state budget or regarding legal technicalities in many other political issues.


The view that the shared premises requirement disadvantages especially religious persons – and in a similar fashion possibly also cultural or political minorities – is unconvincing because of the following reasons. First of all, the requirement does not disadvantage religious beliefs in particular, but controversial views in general. Furthermore, the requirement does not have disadvantageous consequences for religious persons because religious persons are allowed to draw on their religious normative views in political debate – given that these views are overdetermined and translatable in non-religious language. Second, according to the inclusive reading of the requirement, religious persons are allowed to refer to all of their most important controversial beliefs, provided that they support their arguments also with largely shared premises. Finally, even an exclusive reading of the requirement does not necessarily disadvantage religious persons, since it only applies where religious beliefs become relevant in political debate.


Ackerman, Bruce, Social Justice in the Liberal State, New Haven 1980

– Why Dialogue?, in: Journal of Philosophy, 86 1989, 5-22

Nagel, Thomas, Moral conflict and political legitimacy, in: Philosophy and Public Affairs, 16 1987, p. 215-240

Perry, Michael J., Politics, Morality, and Law. A Bicentennial Essay, New York/Oxford 1988

– Neutral Politics?, in: The Review of Politics, 51 1989, 479-509

– Love and Power. The Role of Religion and Morality in American Politics, Oxford 1991

– Religion in Politics. Constitutional and Moral Perspectives, Oxford 1997

– Why Political Reliance on Religiously Grounded Morality Is Not Illegitimate in a Liberal Democracy, in: Wake Forest Law Review, 36 2001, 217-249

– Under God? Religious Faith and Liberal Democracy, Cambridge 2003

– The Political Morality of Liberal Democracy, Cambridge 2009

Rawls, John, The Domain of the Political and Overlapping Consensus, in: New York University Law Review, 64 1989, 233-255

– Reply to Habermas, in: The Journal of Philosophy, 92 1995, 132-180

– The Law of Peoples. With “The Idea of Public Reason Revisited”, Cambridge/MA 1999

Smith, Steven D., Separation and the Secular, in: Texas Law Review, 67 1989, 955-1032

Solum, Lawrence B., Inclusive Public Reason, in: Pacific Philosophical Quarterly, 75 1994, 217-231


1 Just consider Perry’s many books on this and similar issues (Perry 1991, Perry 1997, Perry 2003, Perry 2009). For a statement on the development and change in Perry’s view, see Perry 2001, 221 (footnote 14): “Although I have addressed this issue [the proper role of religiously grounded morality in the politics and law of the United States] in two books, (…) my thinking has continued to develop and to change.”

2 As John Rawls points out, Bruce Ackerman treats important political liberal themes already in his book Social Justice in the Liberal State (Ackerman 1980), where he “defends the relative autonomy of political discussion governed by his principle of neutrality and […] considers various ways of arriving at this idea of political discourse” (Rawls 1995, 133).

3 To be a bit more technical about this point, it is not always the case that desiring A and B implies that I want A independent of B. Thus, it is not necessarily the case that IF d(A&B) THEN d(A) & d(B). Someone who desires a white coffee does not desire, firstly, milk and, secondly, coffee. She desires coffee with milk (in a specific combination).

4 To be again a bit more technical, the daughter assumes that if x is a subset of Z and S wants Z, then S want x as well, which is not always true, as the example with the white coffee in the note above indicates.

5 As Lawrence Solum puts it, “we should adhere to an ideal of public reason that is inclusive”, that is, an ideal “that requires citizens to advance public reasons in public debates on political questions, but that does not require them to exclude supporting non-public reasons from such debate” (Solum 1994, 218-219).

6 Regarding his “wide view of public political culture and discussion”, John Rawls holds that “reasonable comprehensive doctrines, religious or nonreligious, may be introduced in public political discussion at any time, provided that in due course proper political reasons – and not reasons given solely by comprehensive doctrines – are presented that are sufficient to support whatever the comprehensive doctrines are said to support” (Rawls 1999, 152). Rawls calls this “the proviso” (ibid., emphasis in the original).

7 Note that premises might be shared even though it is contested that they are shared. Thus, the shared premises requirement is different, and more plausible, than a non-controversial premises requirement. A condition for reasons not to be controversial would be too strong and would reduce political discussion to the exchange of platitudes.