Leo Strauss believes there is a truth about human nature that can in principle be known to humanity.

Read 'believes' as a description of Strauss's position, since he died in 1973. Judge against Strauss's own works, such as Natural Right and History and What Is Political Philosophy?, and mainstream Strauss scholarship. True: Strauss's writings and the prevailing scholarly reading hold that he affirmed a permanent truth about human nature, or natural right grounded in it, that is knowable in principle by human reason. Mostly true: he affirmed that such a truth exists and is accessible to philosophy, while stressing that philosophy is mainly awareness of the fundamental problems, or that only a few can attain such knowledge. Mixed: scholarship is substantially divided, with credible readings treating his position as zetetic or sceptical about whether the truth can actually be known. Mostly false: the dominant reading is that Strauss doubted such truth could be known, with only limited textual support for the claim. False: Strauss explicitly denied that there is a knowable truth about human nature.

Set before the research began.

1. E1 Leo Strauss: Escaping the Stifling Clutches of Historicism ~ The Imaginative Conservative The Imaginative Conservative · 8 April 2016

   “For example, we know in our understanding of the whole that things have unalterable essences; more particularly, we know “that there is an unchangeable human nature.””

2. E2 Leo Strauss Stanford Encyclopedia of Philosophy · 1 December 2010

   “In Natural Right and History Strauss does not deny that we can know right and wrong, but he does question strongly whether philosophy in and of itself can defend a universal morality beyond that of a closed city or society.”

3. E3 Leo Strauss Stanford Encyclopedia of Philosophy · 1 December 2010

   “Natural Right and History asks, though does not answer, the question of whether it is possible to return to some concept of nature for understanding who we are as human beings and therefore to some notion of absolute moral standards.”

4. E4 Leo Strauss Stanford Encyclopedia of Philosophy · 1 December 2010

   “Therefore, the right way of life cannot be established metaphysically except by a completed metaphysics, and therefore the right way of life remains questionable”

E1 quotes Strauss saying that "we know" there is "an unchangeable human nature", which directly supports the claim that he affirmed a knowable truth about human nature. The Stanford Encyclopedia entry adds the qualifications. It says Strauss did not deny that we can know right and wrong (E2). It also says Natural Right and History asks, without answering, whether a return to nature is possible (E3), and that the right way of life "remains questionable" without a completed metaphysics (E4). Taken together, the evidence fits the "mostly true" criterion: Strauss affirmed that such a truth exists and is accessible, while stressing that the fundamental problems remain open.