 Rawls conjectures in Theory that the argument in the OP “aims eventually to be strictly deductive….a kind of moral geometry” (TJ 121/104–5; see also JF 17, 83). This is not a concession to Hume’s argument, since Rawls envisions the parties’ selection of the principles of justice as part of this conjectured deduction (JF 133). Moreover, even assuming there is a very complicated deductive proof (not what Hume envisioned) of the principles of justice that does not rely on a hypothetical contract. Rawls’s attitude would be that the original position argument still serves as a useful heuristic for public reason that enables citizens to understand the enormous complexities of this conjectured proof. Finally, Rawls later qualifies his claim of deductive proof and says that in fact the argument from the original position cannot “fully attain” an ideal of rigorous deductive reasoning; for there are indefinitely many considerations to be appealed to in the original position, and deciding the balance of reasons in favor of the principles of justice depends, not on deduction, but “on judgment informed and guided by reasoning” (JF 133–4). 