What is especially needed is not so much a theory of advertising and its effects as a critical study of a great variety of particular ads by a diversity of minds using multiple approaches. (Advertising as a Magical Institution, 1952)¹

When Alanbrooke discussed strategy with the Americans he was baffled by their preference for global strategy: “again discussion of global strategy which led us nowhere. The trouble is that the American mind likes proceeding from the general to the particular whilst in the problems we have to solve we cannot evolve any sort of general doctrine until we have carefully examined the particular details of each problem.” (Item #21, Explorations 8, 1957)²

like Poe, Mr. Eliot insists on precision achieved by experiment with the art-form used as pilot model. The ultimate causes are tapped in the audience by the art model, the model being used as a control mechanism. The artist here, like the scientist, experiments with the effects of a model until the exact causes are discovered and brought to bear. This method might be called the method of invention itself. And A. N. Whitehead, in Science and the Modern World, pointed out that this fact was the prime discovery of the nineteenth century rather than the discovery of any applied process. For communicators in any medium this method is now indispensable, whether in advertising, in politics, in education, in art. Because a general scattering of shots may not only be wasteful, but it may, in an electronic world of simultaneous effects, touch off unforeseen chains of reaction. The Poe-Eliot method is not only efficient, it is now necessary, and anything less is in fact irresponsible. [For only] in periods or areas when information moved at a pre-electronic pace, [could] the effects of the through-put of information with reference to any given social structure of knowledge and attitudes be counted on to be manageable.³ (Media Alchemy in Art and Society, 1958)⁴ 

In a handwritten letter to Harry Skornia from June 25, 1959, McLuhan put forward some thoughts on science. Part of his point was to locate his NAEB ‘Understanding Media’ project in relation to the sort of ‘normal science’ the NAEB research committee (and on some days also Skornia)⁵ hoped that the project would quickly begin to practice. For McLuhan, in fundamental contrast, normal science was the goal of the exercise which could not be reached if the assumption were made that its requirements were already in place.

Dear Harry
Perhaps I can clarify a bit more my recently stated questionnaire approach [within the Understanding Media project] in reference to grammars of the media.  [The idea is] to ask in written and oral form:
what is the most obvious and striking power or advantage possessed by your medium (lead pencil, typewriter, radio station) over all other means?
what has your medium done to other media?
what have other media done to yours?
These by way of eliciting observation and anecdote that will reveal the various lines and levels of force operative in any field of relations set up by any medium.
[The ability] to discern and to spell out the lines of force in the world gives us [ordinary] speech, statement, syntax in the first place.  To do this for various segments of reality (physics, chemistry, logic, rhetoric) in a more detailed way is science.  And science in turn produces new media or modes of handling information which like the older languages have their own lines of force and impact for which grammars [of such media]⁶ or [a] science [of them] can be discerned.
To codify these grammars [in an initial way] or lines of force [as they are unreflectively manifested] in new media must be done by contact with those who are nearest to these media.  But the technicians have no unified procedure of verbalized handling of their experience.  Nor do those closest to the new media have much awareness of the interpenetration of media in man and society.
So Harry, I’m suggesting a descriptive “unified field” approach via particular [unfocused]⁷ observation and anecdote as the preliminary basis for later [focused] experiment and testing.⁸

McLuhan made a series of explicit and implicit points:

• the required science of media was yet to be initiated and would not be initiated at all if the science we have in the rear-view mirror is presupposed as applicable to media
• one sign of the absence of science was that existing “technicians have no unified procedure of verbalized handling of their experience”
• conversely, one way to proceed toward science would be to attempt to find a vocabulary which would enable the required unification of designation and so the collective investigation that would be enabled by it
• since “science in turn produces new media or modes of handling information” and since there is profound “interpenetration of [such] media in man and society” producing revolutionary change in both, the potential of the project to solve currently unsolvable problems was vastly more far-reaching than the NAEB imagined — a prospect that should act as a spur to brave the unfamiliarities on the way to science⁹
• another problem that could give direction to the project — like the  designation problem — was the hall of mirrors effect in the fact that “science in turn produces new media or modes of handling information which like the older languages have their own lines of force and impact” (and so on, ad infinitum). The potential for such infinite regress is never absent from human activity, but at the same time does not present an insuperable problem for it. We simply go about our business. A science of media, and particularly a science of sciences, must acknowledge such regress — and endure the finitude which is its motor! We never get to some one fixed foundation for our investigations both because other views are always possible and because our own views are never definitive. Hence, what stands in the way of science can either be too little consciousness of imperfection (like the NAEB notion that the requirements for a science of media were already in place) or too much consciousness of imperfection (like the supposition that while sciences of nature are possible, sciences of human nature are not). McLuhan’s central point to the NAEB was that the passage between this Scylla and Charybdis had to be taken and that it therefore gave an unmistakable signpost of the required way.¹⁰