Rawls and subject 22
Still, it may remain unclear for the reader in what way precisely the above definitions, procedure and conception come together to constrain political discourse and deliberation. Indeed, more needs be said not merely on the content of public reason but, relatedly, on its scope. The author sketches out the latter in writing:
To begin: in a democratic society public reason is the reason of equal citizens who as a collective body, exercise final political and coercive power over one another in enacting laws and in amending their constitution. The first point is that the limits imposed by public reason do not apply to all political questions but only to those involving what we may call “constitutional essentials” and questions of basic justice […] This means that political values alone are to settle such fundamental questions as: who has the right to vote, or what religions are to be tolerated, or who is to be assured fair equality of opportunity, or to hold property. These and similar questions are the special subject of public reason.
These self-imposed limits to public reason’s scope must be taken seriously if we are not to mischaracterize Rawls’ position. Political considerations, delimited under the aegis of public reason and in accordance with the representational device of the original position, can only decide the most basic questions in society: those regarding constitutional rights and institutions of distributive justice. If the author insists on these limits, it stems from the concern to properly delimit what public reason, and, by extension, pro tanto justification, can and cannot hope to achieve. For not all political questions come under the purview of public reason. Consider that:
Many if not most political questions do not concern those fundamental matters, for example, much tax legislation and many laws regulating property; statutes protecting the environment and controlling pollution; establishing national parks and preserving wilderness and animal and plant species; and laying aside funds for museums and the arts. Of course, sometimes these do involve fundamental matters. A full account of public reason would take up these other questions and explain in more detail than I can here how they differ from constitutional essentials and questions of basic justice and why the restrictions imposed by public reason may not apply to them; or if they do, not in the same way, or so strictly.
Insofar as many matters of public concern do not bear on the make-up of basic institutions, e.g. the executive, legislative or judicial, nor on the basic rights of the democratic subject and the mechanisms for distributive justice, public reason does not dictate what kinds of reasons are to be offered when laying out, defending or modifying a given position on matters of this kind. At this stage, it may prove useful to coin a distinction between properly political questions, to which public reason applies, and merely public questions which may arise both in political, public and nonpublic forums and to which public reason need not apply.
From there, one may naturally conclude, as Rawls does, to the situations which call for public reason and, by extension, pro tanto justification. Importantly, one should also note that public reason constrains government officials and citizens in different ways. For the former, Rawls deems the constraints particularly stringent as public reason:
[…] applies in official forums and so to legislators when they speak on the floor of parliament, and to the executive in its public acts and pronouncements. It applies also in a special way to the judiciary and above all to a supreme court in a constitutional democracy with judicial review. This is because the justices have to explain and justify their decisions as based on their understanding of the constitution and relevant statues and precedents.
 PL, p. 214.
 PL, pp. 214-5.
 As Rawls seems to allow, one can imagine circumstances in which institutional or rights aspects come up with such topics, e.g. whether the need to combat climate change can entail considerable alterations to goods, public and private, to which the subject’s rights would ordinarily entitle her. In such a case, both public and nonpublic reasons might be introduced therein depending on the particulars of the case.
 It should be noted that Rawls makes an analogous distinction with regards to forum or audience, i.e. between “public forum” and “background society” (see PL, pp. ____ ). That said, the distinction could be made clearer regarding the difference between political (between government officials), public (between the former, politically engaged citizens and the broader public) and nonpublic (between both of the former and nonpublic associations). This multiplication of kinds of questions and kinds of public may allow for greater clarity by providing question-audience couplings, e.g. political-political, political-public, political-nonpublic, etc., when the time comes to reaffirm what public reason can or cannot do. One could further refine this by specifying the speaker as well.
 PL, pp. 215-6.