Richard Rorty studied with Richard McKeon as an undergraduate and master’s student at the University of Chicago. 

Richard McKeon, an admirer of Aristotle, dominated the philosophy department at Chicago in those days. A committee he headed had dreamt up a nonstandard introductory philosophy course called “Observation, Interpretation and Integration.” I was anxious to start studying philosophy, so I signed up to take OII in my second year at Chicago. (5)¹

Rorty then did his PhD at Yale, but continued to consider McKeon:

[Paul] Weiss was my dissertation advisor, but the dissertation owed less to his influence than to McKeon’s. An ungainly six hundred pages, it was titled “The Concept of Potentiality” and discussed Aristotle’s account of dynamis in the ninth book of his Metaphysics, Descartes’s dismissive treatment of the Aristotelian potency-act distinction, and Carnap’s and Goodman’s treatment of subjunctive conditionals and of nomologicality². McKeon had specialized in such comparisons and contrasts between philosophers of different epochs. At Yale I was applying techniques I had learned at Chicago. (8)

McKeon’s 1935 paper offered two contrasting ways of advancing from the  “debate” of the three arts of the trivium (dialectic, grammar and rhetoric). Both ways emerged from the determination that the quarrel of the trivial arts is foundational and therefore “persistent”. It was forever irreducible to any one of the three. McKeon remarked, “controversies (…) did not go out of the world” (95) and, indeed, could not go out of the world. 

One pathway from this crossroads could be illustrated from Luther:

Here the extreme of value is put upon uncertainty. This humble despair of all human powers is behind Luther’s strictures against the scholastics for their too great confidence in reason: no reason of man can be taken as certain, for the wisdom of the world is made stupid by God… (McKeon, 1935, 104-105)

Quite aside from God (if anything can be said to be quite aside from God), “no reason of man can be taken as certain” in relation to the debate of the trivial arts because the working of the “debate” is deeper than human beings. As the precondition to what McKeon termed “verbal expression in general”, it is already there before we express anything at all in word or deed, is then variously at work in every expression we attempt, and it remains always there again after we have done so. It may well be said, then, that the “extreme of value is put upon uncertainty”, since all human expression stands before this prior multiplicity and is never determined beforehand in only one of its contesting directions.  

However this might inculcate a fitting humility, it would be wrong to conclude any necessary “despair” from it. Hence, if Rorty (for example) took this “uncertainty” track out of McKeon’s work, he certainly did not do so out of despair, but from the determination that dogged persistence in thought and action in an attempt to put things right was indicated — and that this was enough for beings who are finite in every way. The aspiration to an organized discipline could, he apparently thought, only detract from the required uncertain assessment of the human situation and of our responses in and to it.³

The other pathway was Gilson’s⁴ ‘philosophy’.⁵ This ‘nomological’ option was broached at the end of McKeon’s essay in conclusion to it:

when the distinctions [between the arts of the trivium] which have been employed in this essay have been fortified by (…) further materials, it will be time to consider dialectical resolutions, the problems of philosophy and their evolution and finally the character of philosophic truth. (110)

When, however, two [or more] theories [deriving from different arts of the trivium] are set one against the other, when the question of (…) truth (…)⁶ is raised, the technique of the dialectician is needed. So long as there is no two-voiced controversy, the question may remain on the grammatical or on the rhetorical level. (112-113)⁷

though each interpretation [of each the three trivial arts] is impregnable within its own limits,⁸ when brought into controversy [between them] the debate is ultimately dialectical.⁹ (111)

Once that philosophic view has been established, however, it may not be impossible to show that there are canons of criticism for history according to which one manner of interpretation is preferable to another. (113)

in segregating the philosophic problems involved in history, the character of philosophic problems themselves might be shown more clearly for the examination of what is involved in the making of statements. (113-114)  

McLuhan shared with Gilson, at least,¹⁰ the notion that the interior landscape of human beings was just as subject to scientific investigation as the external one. But this would be based, like all sciences, not on some absolute insight (whatever that might be), but on collective investigation focused on central organizing conceptions (like Gilson’s and McKeon’s trivial arts) — which conceptions would always remain, however, perpetually open in principle to scientific revision and even revolution (as articulated by Rorty’s friend and longtime colleague at Princeton, Thomas Kuhn).¹¹ 

Here is how McLuhan described this nomological possibility from Gilson in his 1954 ‘Catholic Humanism’ lecture:

What [Gilson’s Unity of Philosophical Experience] does is to elicit the image of truth from past errors and to confirm the unity of man’s quest from the jarring discords of unremitting debate. But what I wish to point out is that Gilson’s method is that of contemporary art and science (for contemporary poetry has healed the old breach between art and science). Gilson does not set out to produce a theory or view that will unify the philosophical disputes of the past. He reconstructs the disputes. He enables us to participate in them as though we were there. We see that they were real. (…) By repeating this process of participation (…) we are liberated both from past and present. We don’t arrive at a simple unifying concept but are put on the road to achieving a wisdom. And the road to this wisdom is by way of sympathetic reconstruction, involving the abeyance of personal prejudice and preconception.
(…)
the poetic process as it appears in the work of Poe, Baudelaire and Eliot, and by writers of detective fiction, is also the manifest principle of historical reconstruction as used by Gilson.
(…)
Gilson has used the method of reconstruction in the history of philosophy as a new creative technique which permits a new kind of communication between the present and the past. The reader of Gilson is typically given not a view or theory of the past but the experience of it. But the past as experience is present. It is available once more as nutriment. Previous theories of the past really amounted to a way of disowning it or of explaining it away.
(…)
the traditional errors of men become for the analogical artist precious matter for his structures even as Gilson has used historical error in philosophy to build a path to truth.

In 1954, McLuhan — now in his 40’s and the father of 6 children — was feeling utterly isolated even in the culture and technology seminar. He felt himself called to consider how a finite yet scientific discipline built out of the most unlikely of materials (“the traditional errors of men”) might be instigated and pursued — as a new (yet oldest of the old) “path to truth”.

The path has been known and traversed forever. Every child takes it in learning to speak. Every practical craft and theoretical discipline was and is established through it. However, its communication has never succeeded beyond a small circle and general investigation never initiated. But, McLuhan worried anxiously, was such communication perhaps the only way to avert disaster in a nuclear global village?

Somewhat like fusion in physics, McLuhan’s eventual breakthrough¹² in 1960 must be understood as the product of enormous pressure. Its realization that year would all but kill him.¹³