What is a Tetrad?

Andrew McLuhan
5 min readJan 8, 2016

We found that everything man makes and does, every process, every style, every artefact, every poem, song, painting, gimmick, gadget, theory, technology — every product of human effort — manifested the same four dimensions.” [Laws of Media: The New Science, Marshall and Eric McLuhan, University of Toronto Press, 1988]

This is meant to be a basic introduction to the McLuhan Tetrad. Just enough to get going making tetrads. I don’t intend to get into the even more complicated things like proportion, or the ratio among the elements, the relation to the structure of metaphor. For a more detailed and sophisticated account, please refer to Laws of Media (LoM).

I apologize in advance for some technical language. I’ve tried to write as plainly as I am able to, but some big words are unavoidable, and I prefer not to paraphrase when spending a little time thinking about a direct quote is the best way to engage. Please take the time to read slowly and consider the words… they were chosen carefully.

I am a student and novice in this subject. I am very grateful to Eric McLuhan for his patience in helping me find my way, and for reading this and suggesting (surprisingly few!) changes.

From UMR to LoM

Back in 1964, Marshall McLuhan published Understanding Media: The Extensions of Man (UM). In around 1972, the publisher came to McLuhan about doing a tenth anniversary edition. Marshall thought this was a great idea, a chance to address some of the criticisms he’d received in the years since UM came out. The main criticism he wanted to address was of the “that’s all fine and well, Marshall, but it’s not scientific” type.

So Marshall and Eric McLuhan (who was, at that time, Marshall’s assistant) set about what they referred to as UMR, or, Understanding Media Revised.

In order to address the question of a scientific statement, after a long search for how to actually define ‘scientific statement’, they borrowed from Sir Karl Popper: “something stated in such a manner that it could be disproved.” [LoM viii] So they set about to answer the question “what statements can we make about media that anyone can test — prove or disprove — for himself? What do all media have in common? What do they do?” [LoM, viii] After several weeks of searching, they came up with a solid four statements that could apply in all cases. Because they apply in all cases, they called them Laws. (For a more complete account of this, see the preface to LoM).

Long story short, what they ended up doing with UMR was way more than the publisher was interested in publishing as a tenth anniversary edition. Eric McLuhan managed to get Laws of Media: The New Science published by University of Toronto Press in 1988.

Tetrad - a group of four

‘Tetrad’ means ‘a group of four’ — as ‘triad’ means ‘a group of three’, and ‘dyad’ means ‘a group of two’, et cetera.

The McLuhans’ tetrad is a tool for exploring the effects of media (Figure/Ground analysis is another exploratory tool). It does this through asking four questions. For our purposes, we can define ‘medium’ as a human technology. ‘Artifact’ works as well — ‘an object made a human being.’ This could be a car or a fork, an iPhone or an app. Through testing, the McLuhans found that the field of study is even larger than that:

…we learned that they applied to more than what is conventionally called ‘media’; they were applicable to all the products of human endeavour, and also to the endeavour itself! One colleague at the university tried them on remedies for cancer, and found they worked. With another, my father tried business procedures; with another, Newton’s laws of motion. They worked!” [LoM, ix]

Here, then, are the four questions of the tetrad. Don’t feel you have to ask them in any particular order.

What does _______ enhance?

What does it make obsolete?

What does it retrieve?

And, when pushed to an extreme, what does it reverse or flip into?

ENH (enhance)

First, extension: as an ‘extension of man’ (subtitle to UM) every technology extends or amplifies some organ or faculty of the user.” [LoM viii]

Amplify. Extend. Speed up. Intensify. Increase. Upgrade. Improve the quality, value, reach of… . Every new medium enhances some human faculty or function, or builds upon an existing medium.

OBS (obsolesce)

Then, the attendant ‘closure’: because there is an equilibrium in sensibility, when one area of experience is heightened or intensified, another is diminished or numbed.” [LoM, viii]

Obsolete doesn’t mean dead — just no longer in charge. Out of date. Out of fashion. Version 1.0 when v.2.0 is out. What does the new medium take over from? What does it make unnecessary?

REV (reverse)

…a third, with a chapter of its own in UM (‘Reversal of the Overheated Medium’): every form, pushed to the limit of its potential, reverses its characteristics.” [LoM, viii]

When pushed, a medium will reverse it’s characteristics. For instance, the highway is meant to speed up traffic, make travel easier, but when you have too many cars on the road at once, you get a traffic jam — this is the flip or “reversal of the overheated medium”. The phrase “tipping point” is the point of reversal.

RET (retrieve)

At first we thought retrieval entailed only the recasting of whatever formed the content of the new form. That is does (the content of any medium is an older medium) and considerably more.” [LoM, viii]

Reclaim. Bring back. Revival. Retro. This is the etymology of media, its roots. What’s old is new. There’s nothing new under the sun. Every medium also retrieves some previous medium. To answer this question can be very difficult and requires a lot of knowledge of history and the past.

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We found these four … and no more. He [Marshall] spent the rest of his life looking for a fifth, if there be one, and simultaneously trying to find a single case in which one of the first four doesn’t apply.” [LoM, viii]

There is not one single answer to the questions. There are usually many. Answering the questions can be playful, a game. Treat it like brainstorming, allow answers to come without judgement — worry about judging them later.

The way in which you set out to answer the questions can help or hinder you. The best way I’ve found to do tetrads is with pen and paper. In the centre of the paper write the medium in question, and then write (clockwise, from top left, or around 10 o’clock) ENH, REV (2 o’clock), OBS (4 o’clock), RET (8 o’clock). Then, start to build the tetrad outward. This is, if only visually, a powerful technique in that you’re moving outward to infinity, not into an increasingly smaller, limited space.

It is not necessary to ask them in any particular order. Mix it up. Don’t get stuck — if you don’t get answers right away, move on, let it simmer.

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Thanks for reading. Please get in touch if you have any questions or comments, I’m always happy to hear from you.