Response to “The Quinean Assumption. The Case for Science as Public Reason,” Matteo Bonotti

In “The Quinean Assumption: The Case for Science as Public Reason” (2019), Cristóbal Bellolio examines an aspect that has often, and surprisingly, been overlooked in the extensive literature on public reason and political liberalism: the role of scientific arguments in the process of public justification. Public reason is the idea that laws and policies should be justifiable to all those who are subject to them … [please read below the rest of the article].

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Article Citation:

Bonotti, Matteo. 2019. “Response to ‘The Quinean Assumption. The Case for Science as Public Reason’.” Social Epistemology Review and Reply Collective 8(7): 18-22.

The PDF of the article gives specific page numbers.

This article replies to:

In “The Quinean Assumption: The Case for Science as Public Reason” (2019), Cristóbal Bellolio examines an aspect that has often, and surprisingly, been overlooked in the extensive literature on public reason and political liberalism: the role of scientific arguments in the process of public justification. Public reason is the idea that laws and policies should be justifiable to all those who are subject to them.

Rawlsian Liberalism

The starting point of Bellolio’s analysis is John Rawls’s (2005) well-known claim that public reason allows appealing “to presently accepted general beliefs and forms of reasoning found in common sense, and the methods and conclusions of science when these are not controversial” (Rawls 2005, 224; emphasis added). This statement is often cited by political liberals to show that Rawlsian political liberalism welcomes scientific arguments into the process of public reasoning and public justification. Yet, as Bellolio rightly points out, serious criticisms have been raised against the idea that scientific evidence is a suitable source of public justification. More specifically, some have highlighted its complexity, which renders it inaccessible to ordinary citizens (e.g. Brown 2009, McKinnon 2012), whereas others have pointed out that scientific arguments are as controversial as those advanced from within religious or other comprehensive doctrines, which political liberalism excludes from public reason (e.g. Carter 1994, Plantinga 2001).

In response to these criticisms, Bellolio persuasively argues a) that the complexity of science is not an issue, since scientific reasoning is only a more sophisticated version of the everyday reasoning that ordinary citizens employ in their daily lives, differing from the latter only in degree but not in quality, and b) that the scientific method is also recognized as valid by religious citizens and therefore is not as controversial as some critics suggest.

I am very sympathetic to Bellolio’s argument but I would like to focus on three aspects that could have perhaps been further elucidated.

Aspect One: Scientific Arguments and Public Reasoning

The first concerns an assumption that seems to underlie Bellolio’s analysis. This is the idea that scientific arguments may only be appealed to in the process of public reasoning if they are the object of scientific consensus. For example, Bellolio claims that “[a]s long as the experts continue arguing over undecided scientific matters, these competing claims cannot demand their recognition as public reasons. However, as soon as an overwhelming scientific consensus is obtained—as in the case of evolutionary theory and climate change—these reasons are considered public” (2019, 212).

Here, Bellolio seems to underestimate the degree of disagreement that characterizes the scientific community. It is true that, to some extent, scientists overwhelmingly agree, say, that climate change is a fact. However, this consensus may often exist at a very general level. For example, Kevin Vallier points out that while scientists agree on climate science’s scientific method, they may disagree on “climate change models that generate specific predictions about how much, say, sea levels will rise due to increased carbon emissions” (Vallier 2014, 28; see also Badano and Bonotti forthcoming).

Many scientific conclusions are, like the one in Vallier’s example, specific rather than general, and normally the object of more or less significant disagreement within the scientific community. Does this prevent such conclusions from being considered public reasons? According to Bellolio, yes. And this also seems to be a key implication of Rawls’s aforementioned statement that public reason includes “the methods and conclusions of science when these are not controversial” (Rawls 2005, 224; emphasis added). But this seems to imply that we would be left with very few science-based public reasons, given the level of scientific disagreement on most issues. However, this need not be the case.

One way of avoiding this unwelcome conclusion is by considering an aspect of public reason that Bellolio seems to overlook: its structure. Many public reason liberals who endorse “consensus” conceptions of public reason[1] often refer to public reasons as reasons that are “shared” among the citizens of a liberal polity. However, there is another way of understanding the “publicness” of reasons. This is the idea of “accessibility”, i.e. the view that for a reason to be public, citizens only need to share the reasoning standards behind it but not the reason itself (Vallier 2011, 2014).[2]

To return to the aforementioned example, climate science’s scientific method provides the shared reasoning standards based on which different scientists employing such standards (without making any obvious mistakes in the process) can reach different conclusions and develop different climate science models. The key point is that under the accessibility conception of public reason even scientific conclusions that are the object of scientific disagreement can still be considered public reasons (Badano and Bonotti forthcoming). Bellolio, who rejects this view, therefore seems to implicitly rely on a shareability conception of public reason. This risks narrowing quite significantly the range of scientific conclusions that can count as public reasons, given how many, among such conclusions, are considered controversial within the scientific community. Perhaps a reflection on the structure of public reason would have helped Bellolio to avoid this problem.

Aspect Two: The Normative Effect of Scientific Conclusions

Focusing on the structure of public reason can also help us to clarify a second aspect of Bellolio’s argument. Bellolio (2019, 214) rejects “scientism” and argues that scientific conclusions “lack normativity” and must be accompanied by “other (public) reasons”. This is an important claim, which also points to an often overlooked distinction within the literature on public reason. More specifically, not only is it important to distinguish between shareability and accessibility conceptions of the structure of public reason.

It is also important, within the accessibility conception, to distinguish between the different types of reasoning standards which are behind public reasons. These include both “prescriptive and descriptive” (Vallier 2016, 607) standards. The latter include the reasoning standards of science, whereas the former include both epistemic guidelines of inquiry and, crucially, substantive political values such as liberty, religious freedom and gender equality, which are widely shared among the reasonable members of a liberal society and provide public reasons with normativity (Badano and Bonotti forthcoming; Bonotti 2017, 115). In other words, scientific conclusions per se can rarely guide political action unless they are accompanied by the aim to realize certain political values. At the same time, though, one could argue that the realization of political values cannot prescind from the evidence provided by scientific inquiry. This seems to imply that prescriptive and descriptive reasoning standards are jointly necessary for public reason. The accessibility view of public reason therefore helps us to clarify this further aspect of Bellolio’s argument.

Aspect Three: Citizens and the Process of Public Reasoning

My third and final observation concerns another implicit assumption that seems to underlie Bellolio’s analysis. This is the view that all citizens should be involved in the process of public reasoning, which includes the evaluation of reasons put forward by scientists. This is what generates the need to address the complexity challenge posed by scientific reasoning, which Bellolio persuasively addresses by relying on the Quinean assumption. It is this assumption that also allows Bellolio to conclude, following Gaus (2011), that

many established scientific facts will never qualify as public if the benchmark is accessibility to actual constituencies. But it is a different story against the benchmark of weakly idealized constituencies … [whose members hold] … beliefs that their real-world counterparts would be justified in holding after engaging in a ‘respectable amount’ of good reasoning [since there is only a difference of degree, but not of kind, between scientific and everyday reasoning] (2019, 212).

While this is a persuasive claim, I believe that this argument still imposes significant burdens on ordinary citizens. Someone will have to evaluate the reasons put forward by scientists. But that evaluation will have to be carried out from outside the scientific community, if we want scientific reasons to count as public reasons. Indeed, Bellolio seems to suggest that ordinary citizens will be involved in that evaluation (2019, 208). However, this may be quite demanding for them. It implies that citizens will need to move closer to their weakly idealized counterparts in order to be able to properly evaluate scientific reasons. This, though, seems unnecessary.

The view that public reason imposes direct constraints on all citizens (including not only the duty to refrain from appealing to controversial reasons, what Rawls (2005) calls the “duty of civility,” but also the duty to evaluate other citizens’ reasons) is not one we need to embrace. A different way of understanding public reason is via an indirect approach, which

allows citizens to forgo explicit attempts in political deliberation and action to bar excluded reasons from playing a justificatory role. The indirect approach focuses instead on regulating the behavior of politicians and the structure of political institutions to ensure that excluded reasons do not generate publicly unjustified law (Vallier 2014, 51; emphasis added).

This approach therefore requires public institutions, and those who occupy key roles within them, to monitor the reasons advanced in support of laws and policies, and ensure that only those reasons that meet the standards of public reason are ultimately employed to justify legislation. While this argument is often used in connection with the exclusion of religious arguments from public justification, it clearly offers important tools for dealing with scientific reasons too. After all, public officials, including elected representatives, civil servants, and members of the judiciary, often have the time, resources and, sometimes, expertise, to evaluate scientific reasons more comprehensively than ordinary citizens. They are, in other words, closer to the members of the aforementioned weakly idealized constituency that can formulate and evaluate scientific arguments. And even when they cannot do so in isolation, public officials have access to the institutional forums, resources and expertise through which they can collaboratively engage in a comprehensive process of reason evaluation. The indirect approach to public reason therefore may offer a more concrete and realistic model for the evaluation of scientific arguments than the one which seems to implicitly characterize Bellolio’s argument. This is not to say, however, that Bellolio’s argument could not be modified in order to include this dimension.

These critical remarks, it should be noted, do not aim to detract from the quality of Bellolio’s analysis, which I found by and large persuasive. Instead, they only intend to highlight the importance of enriching and refining the analysis of the place of scientific arguments in public reason liberalism through the lens of key analytical distinctions such as those concerning the structure and key sites of public reason.

Contact details: Matteo Bonotti, Monash University,


Badano, Gabriele and Matteo Bonotti. forthcoming. “Rescuing Public Reason Liberalism’s  Accessibility Requirement.” Law and Philosophy.

Bellolio, Cristóbal. 2019. “The Quinean Assumption. The Case for Science as Public Reason.” Social Epistemology 33 (3): 205-217.

Bonotti, Matteo. 2017. Partisanship and Political Liberalism in Diverse Societies. Oxford: Oxford University Press.

Brown, Mark B. 2009. Science in Democracy: Expertise, Institutions, and Representation. Cambridge, MA: MIT Press.

Carter, Stephen L. 1994. The Culture of Disbelief: How American Law and Politics Trivialize Religious Devotion. New York: Anchor Books.

Gaus, Gerald. 2011. The Order of Public Reason. Cambridge: Cambridge University Press.

McKinnon, Catriona. 2012. Climate Change and Future Justice. Precaution, Compensation and Triage. Abingdon-on-Thames: Routledge

Plantinga, Alvin. 2001. “Methodological Naturalism?” In Intelligent Design Creationism and its Critics: Philosophical, Theological, and Scientific Perspectives, edited by Robert T. Pennock, 339–361. Cambridge, MA: MIT Press.

Rawls, John. 2005. Political Liberalism. Expanded edition. New York: Columbia University Press.

Vallier, Kevin. 2011. “Against Public Reason Liberalism’s Accessibility Requirement.” Journal of Moral Philosophy 8 (3): 366–89. doi:

Vallier, Kevin. 2014. Liberal Politics and Public Faith. New York: Routledge.

Vallier, Kevin. 2016. “In Defence of Intelligible Reasons in Public Justification.” The Philosophical Quarterly 66 (264): 596-616. doi:

[1] I set aside, here, a discussion of ‘convergence’ theories of public reason (e.g. Gaus 2011; Vallier 2014).

[2] Bellolio often uses the terms ‘accessible’ and ‘inaccessible’ but not in this specific technical sense.

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  1. Quine, Science, and Political Liberalism: A Reply to Bonotti, Badano, and Gómez-Aguliar, Cristóbal Bellolio – Social Epistemology Review and Reply Collective

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