¹ I follow Anderson's understanding of Mill's experiments in living. See Anderson, Elizabeth, ‘John Stuart Mill and Experiments in Living’, Ethics 102 (1991), pp. 4–26CrossRefGoogle Scholar. They are alternative modes of living that investigate alternative conceptions of the good or right. The alternative modes of living then serve as empirical tests of these concepts. These can be done by a single individual (as exemplified, Anderson argues, by Mill's exit from depression by reading poetry), or by a larger group. Examples of this latter group are kibbutzim, or other forms of communes.

² I follow Rawls's account of public reason Rawls, John, ‘The Idea of Public Reason Revisited’, Chicago Law Review 64 (1997), pp. 765–807CrossRefGoogle Scholar. In particular, I wish to focus on the idea of public reason as eliminating comprehensive moral doctrines and having those reasons ‘be replaced by an idea of the politically reasonable addressed to citizens as citizens’ (p. 766). The two features that I focus on are, first, that the scope of reasons is rather constrained, and second, that they are meant to be justifying reasons. The importance of both features will become apparent later in the article.

³ I discuss my account of perspectives in much greater length in Ryan Muldoon, ‘Diversity and the Social Contract’ (unpublished PhD thesis, University of Pennsylvania, 2009).

⁴ Page, Scott E. discusses this idea in detail in The Difference: How the Power of Diversity Creates Better Groups, Firms, Schools and Societies (Princeton, 2008)Google Scholar. Gaus, Gerald also has applied it to thinking about conceptions of justice in The Order of Public Reason: A Theory of Morality and Freedom in a Diverse and Bounded World (New York, 2010)CrossRefGoogle Scholar.

⁵ This follows from the No Free Lunch theorem in search and optimization theory. The main result is from Wolpert, D. H. and Macready, W. G., ‘No Free Lunch Theorems for Optimization’, IEEE Transactions on Evolutionary Computation 1 (1997), pp. 67–82, at 67CrossRefGoogle Scholar. Not only is there no best perspective, but across all possible problems that one might use perspectives to help develop a solution, all perspectives perform equally well. The question becomes which collection of perspectives might be useful in certain contexts, which we cannot know a priori.

⁶ Here we can suffer from echo chambers and belief polarization. Sunstein, Cass's Going To Extremes: How Like Minds Unite and Divide (New York, 2009) is a clear introduction to this phenomenonGoogle Scholar.

⁷ For a detailed discussion of this, see Bicchieri, Cristina's The Grammar of Society (New York, 2006), esp. ch. 2, sect. 6Google Scholar.

⁸ According to Bicchieri, a norm is a behavioral rule R in a context C for some population P, for which individual agents have a conditional preference to follow R if their empirical and normative expectations are met. An agent's empirical expectations are that she believes that enough other people from her relevant group are also following the norm. Her normative expectations are that she believes that a sufficient number of other people in her relevant group believe that she should follow the norm (and may sanction her to induce compliance).

⁹ Bicchieri, The Grammar of Society, discusses mini-skirts; Muldoon, Ryan, Lisciandra, Chiara, Bicchieri, Cristina, Hartmann, Stephan, Sprenger, Jan, ‘On The Emergence of Descriptive Norms’, Politics, Philosophy and Economics 13 (2014), pp. 3–22 discuss fashion in generalCrossRefGoogle Scholar.

¹⁰ To be clear, I would not argue that being different is the only way of developing one's higher faculties. It is plausible that moral agents can critically reflect on customs and come to decide that they embody the plan of life most suitable to the agent. The key issue is whether that agent chooses to follow a customary way of life because others do and the agent wishes to fit in, or instead the agent has autonomously chosen that a customary plan of life best matches her concept of the Good. The advantage in this context of talking about counter-customary behaviour is that it is easier to see evidence of individual autonomy. This is particularly relevant for encouraging an environment that promotes the development of individual autonomy – in an environment that is demonstrably diverse, there is readily available evidence that people are not stifled by custom. In a more custom-dominant environment, a natural inference would be that people are motivated to follow customs, even if there is a high level of autonomous choice happening behind the scenes. Since our motivations are infrequently made public in the way our actions are, customary actions are motivationally ambiguous in ways that experiments in living are not.

¹¹ I discuss this at great length in ‘Diversity and the Social Contract’.

¹² For instance, the recent debate in the United States over an employer mandate to provide insurance that includes free birth control pill prescriptions as part of the Patient Protection and Affordable Care Act resulted in religious schools and hospitals becoming convinced that they were being targeted by the government. Although I disagree with their analysis, it is true that their religious motivations for wanting to restrict access to birth control pills were excluded from public reason deliberation. Even if the Catholic perspective's recommendations would not have ultimately convinced others, their exclusion signals to Catholics that they are unable, as Catholics, to participate fully in the public sphere. This general problem becomes more extreme when we consider less-mainstream comprehensive moral doctrines, such as Hinduism, Islam, or even Atheism. Individuals with perspectives shaped by these views will be forced to conform to an alien perspective if they wish to be full participants in democracy. This ultimately stifles their views, and could well lead them to refuse to participate in public life.

¹³ Of course, this is not to say that racial supremacist views have a pretty good chance of being useful to our conception of justice in the future. It is just to say that, across all perspectives, we cannot know in advance what elements of them might be able to offer us pertinent, or even crucial, insights into a public conception of justice. Elminating them from debate upfront, rather than letting them demonstrate their uselessness or utility, weakens our efforts to better understand what comprises justice.

¹⁴ Reichenbach, H., ‘On Probability and Induction’, Philosophy of Science 5 (1938), pp. 21–45CrossRefGoogle Scholar. Reprinted in Logic, Probability and Epistemology, ed. S. Sarkar (New York, 1996), pp. 69–94.

¹⁵ Baier, Kurt, The Moral Point of View (Ithaca, 1958)Google Scholar.

¹⁶ Relevant works here are Hull, David, Science as a Process: An Evolutionary Account of the Social and Conceptual Development of Science (Chicago, 1988)CrossRefGoogle Scholar; Kitcher, Philip, ‘The Division of Cognitive Labor’, Journal of Philosophy 87 (1990), pp. 5–22CrossRefGoogle Scholar; Kitcher, Philip, The Advancement of Science (New York, 1993)Google Scholar; Strevens, Michael, ‘The Role of the Priority Rule in Science’, Journal of Philosophy 100.2 (2003), pp. 55–79CrossRefGoogle Scholar; Weisberg, M. and Muldoon, R., ‘Epistemic Landscapes and the Division of Cognitive Labor’, Philosophy of Science 76 (2009), pp. 225–52CrossRefGoogle Scholar; Agostino, Fred D’, ‘From the Organization to the Division of Cognitive Labor’, Politics, Philosophy and Economics 8 (2009), pp. 101–29CrossRefGoogle Scholar; Muldoon, Ryan, ‘Diversity and the Division of Cognitive Labor’, Philosophy Compass 8 (2013), pp. 117–25CrossRefGoogle Scholar.

¹⁷ In a way this anticipates Harsanyi's conditions on his preference utilitarianism, in which he claims that preferences that are directly anti-social should not count in the utilitarian calculus.

¹⁸ The author would like to acknowledge Sebastiano Bavetta, Cristina Bicchieri, Samuel Freeman, Gerald Gaus, and an anonymous reviewer for their invaluable comments and suggestions. This publication was made possible in part through the support of a grant from the John Templeton Foundation. The opinions expressed in this publication are those of the author and do not necessarily reflect those of the John Templeton Foundation.