In his 2017 book, Artefacts of Writing: Ideas of the State and Communities of Letters from Matthew Arnold to Xu Bing, Peter McDonald makes a series of observations on McLuhan which are utterly mis-taken — but which yet may be taken to point (in the mode of Wittgenstein’s arrows)¹ to central aspects of McLuhan’s project. Here is a sample of McDonald’s take with a running commentary given in the footnotes:²

McLuhan looked back to the Prussian idealist philosopher Wilhelm von Humboldt, citing the following key statement from On the Diversity of Human Language (1836) via Ernst Cassirer and in Susanne K. Langer’s translation:

Man lives with his objects chiefly — in fact, since his feeling and acting depends on his perceptions, one may say exclusively — as language presents them to him. By the same process whereby he spins language out of his own being, he ensnares himself in it; and each language draws a magic circle round the people to which it belongs, a circle from which there is no escape save by stepping out of it into another.³

(…) Humboldt saw this as a phenomenon in and of language; whereas McLuhan, like Goody and Watt,⁴ believed that the effects of print were social and political as well as cognitive.⁵ If the ‘Gutenberg revolution’ instituted the ‘fixed point of view’ characteristic of nationalist thinking (…) McLuhan, it should be said, did not appeal to Humboldt merely as an exemplar of nation-centred linguistic relativity.⁶ In keeping with his Utopian vision,⁷ he saw the passage from the Diversity of Human Language as an endorsement of his own ambition to ‘transcend the limitations of our own assumptions by a critique of them’.⁸ Humboldt’s relativism, as he saw it, was fundamentally emancipatory, since he showed⁹ ‘we can now live, not just amphibiously in divided and distinguished worlds, but pluralistically in many worlds and cultures simultaneously’.¹⁰ For him, the ‘global village’ to come was, in other words, not just post-literate but post-national.¹¹ Like many commentators, he ignored the fact that Humboldt, for all his relativism, always insisted on seeing languages as open-ended rather than ‘closed systems’, the expressive potential of which is endlessly extendable…¹² 

What McDonald says McLuhan ignored in von Humboldt — “the expressive  potential [of language] which is endlessly extendable” — is actually what McDonald “like many commentators” ignores in McLuhan: namely, the all important distinction between ‘making’ and ‘matching’ (or ‘merging’). Making is “open-ended”, while matching/merging aims at being ‘closed-ended’ — but can never actually be ‘closed-ended’ given the multiple ramifications of human finitude. 

The “endlessly extendable” nature of all human enterprise operates despite the fact that we are always situated in some or other “magic circle” — “from which there is no escape save by stepping out of it into another”. This may be seen as negative or positive — or both — depending upon context. For McLuhan, the great point is that real communication and real knowing occur despite — or exactly thereby — the fact that no ultimate closure is possible. “The gap is where the action is.” This is most clearly to be seen in language learning by in-fants. Somehow they step from one magic circle to another. But something of the sort occurs in all great art and in all scientific discovery.

As regards the field of media theory, which is no less than the field of all human experience which is never unmediated, never not situated in some or other “magic circle”, the “endlessly extendable” nature of language implicates the possibility that this field, too, may be investigated and mapped. McLuhan’s insistent question: why don’t we get on with the job when so much, even our survival, may depend on it?

Here he is in his Playboy interview:

our survival (…)  is predicated on understanding the nature of our new environment, because unlike previous environmental changes, the electric media constitute a total and near-instantaneous transformation of culture, values and attitudes. This upheaval generates great pain and identity loss, which can be ameliorated only through a conscious awareness of its dynamics. If we understand the revolutionary transformations caused by new media, we can anticipate and control them; but if we continue in our self-induced subliminal trance, we will be their slaves.
Because of today’s terrific speed-up of information moving, we have a chance to apprehend, predict and influence the environmental forces shaping us — and thus win back control of our own destinies. The new extensions of man and the environment they generate are the central manifestations of the evolutionary process, and yet we still cannot free ourselves of the delusion that it is how a medium is used that counts, rather than what it does to us and with us. This is the zombie stance of the technological idiot. It’s to escape this Narcissus trance that I’ve tried to trace and reveal the impact of media on man, from the beginning of recorded time to the present.