Tetrad: Concept

The Resonating Interval:
Exploring the Process of the Tetrad
By Anthony Hempell

The Tetrad: Concept
McLuhan proposed the tetrad as an alternate means for discussing the effect of technology on society. Instead of using a model based on causality, the tetrad organizes an artifact as a "resonating interval": an object which transcends time; and is affected by both its own attributes and the environment which surrounds it. As McLuhan and Powers explain:

...the tetrad performs the function of myth in that it compresses past, present, and future into one through the power of simultaneity. The tetrad illuminates the borderline between acoustic and visual space as an arena of spiraling repetition and replay, both of input and feedback, interlace and interface in the area of imploded circle of rebirth and metamorphosis. (p.9)

The main thrust of the tetrad is to create a "comprehensive awareness" of both the artifact and its surroundings. Creation of tetrads requires the user to strive for a mental balance between acoustic and visual space, requiring the cognitive power of both left and right hemispheres of the brain.

The Process of Tetrad Creation
The tetrad is arrived at through a process of asking questions, based on historical, social, and technological knowledge of the subject:

What does any artifact enlarge or enhance?
What does it erode or obsolesce?
What does it retrieve that had been earlier obsolesced?
What does it reverse or flip into when pushed to the limits of its potential?

These questions result in a set of four effects, namely: enhancement, obsolescence, retrieval, and reversal. These four elements are in a resonant relationship (or "interchange") with one another; the parts of the tetrad are in a complementary relationship:

Table 3: The relationship of tetradic elements

Retrieval is to obsolescence as enhancement is to reversal Retrieval is to enhancement as obsolescence is to reversal
What is brought back, must also render something obsolete; what is enlarged will always do so at the expense of others. What is retrieved is an outgrowth of the enhancement (an ancient version of the same metaphor). What is obsolesced creates opportunity for reversal.

The tetrad is commonly displayed graphically, with the four elements as points of change on the continuum:

Table 4: Elements of the tetrad

Enhancement
(figure)
The amplification of effects, focus on the practical. Creation of vortices of power; solution to previous problem.

The recovery of values and insight that was once lost or eroded. The transition of ground to figure.
Retrieval
(figure)

Reversal
(ground)
The reverse of enhancement; the unexpected dissatisfactions. Pushed to its limits, the artifact flips on its user; creation of new problem.

The erosion of formerly significant artifacts. The transition of figure to ground.
Obsolescence
(ground)

Forward to Tetrads: Past

Retrieval is to obsolescence as enhancement is to reversal	Retrieval is to enhancement as obsolescence is to reversal
What is brought back, must also render something obsolete; what is enlarged will always do so at the expense of others.	What is retrieved is an outgrowth of the enhancement (an ancient version of the same metaphor). What is obsolesced creates opportunity for reversal.