The difference that [which] makes a difference

The DTMD reseach group takes its name (The Difference That Makes a Difference) from Gregory Bateson's 'definition' of information, for which we* normally reference "Steps to an Ecology of Mind".  (Though actually he calls it Difference which makes a difference in Steps - he does use 'that' elsewhere).

* 'We' being members of the DTMD group, especially Magnus Ramage who introduced me to Bateson and especially to the DTMD definition.

I was checking a reference just now, and thought it would be useful to record what exactly he says about the definition.  Here, for reference, are all the instances of the phrase in Steps, with some of the surrounding discussion.

Sources: 

Gregory Bateson Steps to an Ecology of Mind.Collected essays in anthropology, psychiatry, evolution, and epistemology

I've checked the page numbers for two different printings:
 
1972 International Textbook Company Ltd, Aylesbury, UK. ISBN 0700201807. Copyright Chandler Publishing Company 1972

1987 reprint, Jason Aronson Inc. Northvale, New Jersey, London Copyright ® 1972, 1987 by Jason Aronson Inc. ISBN 0-87668-950-0 Downloaded from http://www.edtechpost.ca/readings/Gregory%20Bateson%20-%20Ecology%20of%20Mind.pdf 24/05/2016

1              Chapter “Double Bind, 1969”

“This paper was given in August, 1969, at a Symposium on the Double Bind; Chairman, Dr. Robert Ryder; sponsored by the American Psychological Association. It was prepared under Career Development Award (MH-21,931) of the National Institute of Mental Health.”

In any case, it is nonsense to say that a man was frightened by a lion, because a lion is not an idea. The man makes an idea of the lion.

The explanatory world of substance can invoke no differences and no ideas but only forces and impacts. And, per contra, the world of form and communication invokes no things, forces, or impacts but only differences and ideas. (A difference which makes a difference is an idea. It is a "bit," a unit of information.)

p276 (1987), p271-2 (1972)

2              Chapter “The Cybernetics of "Self": A Theory of Alcoholism”

"This article appeared in Psychiatry, Vol. 34, No. 1, pp. 1-18, 1971. Copyright © 1971 by the William Alanson White Psychiatric Foundation. Reprinted by permission of Psychiatry Section headed “The Epistemology of Cybernetics”"

A "bit" of information is definable as a difference which makes a difference.

p321 (1987), p315 (1972)

More correctly, we should spell the matter out as: (differences in tree) - (differences in retina) - (differences in brain) - (differences in muscles) -(differences in movement of axe) -(differences in tree), etc. What is transmitted around the circuit is transforms of differences. And, as noted above, a difference which makes a difference is an idea or unit of information.

p323 (1987), p317-8 (1972)

3              Chapter “A re-examination of “Bateson’s Rule*”, section “The problem redefined”

*”This essay has been accepted for publication in the Journal of Genetics, and is here reproduced with the permission of that journal”

The technical term "information" may be succinctly de-fined as any difference which makes a difference in some later event. This definition is fundamental for all analysis of cybernetic systems and organization. The definition links such analysis to the rest of science, where the causes of events are commonly not differences but forces, impacts, and the like. The link is classically exemplified by the heat engine, where available energy (i.e., negative entropy) is a function of a difference between two temperatures. In this classical instance, "information" and "negative entropy" overlap.

p386 (1987), p381 (1972)

4              Chapter “Form, Substance, and Difference”. 

“This was the Nineteenth Annual Korzybski Memorial Lecture, delivered January 9, 1970, under the auspices of the Institute of General Semantics. It is here re-printed from the General Semantics Bulletin, No. 37, 1970, by permission of the Institute of General Semantics.” 

But what is a difference? A difference is a very peculiar and obscure concept. It is certainly not a thing or an event. This piece of paper is different from the wood of this lectern. There are many differences between them—of color, texture, shape, etc. But if we start to ask about the localization of those differences, we get into trouble. Obviously the difference between the paper and the wood is not in the paper; it is obviously not in the wood; it is obviously not in the space between them, and it is obviously not in the time between them. (Difference which occurs across time is what we call "change.")

A difference, then, is an abstract matter.

p458 (1987), p457-8 (1972)

I suggest that Kant's statement can be modified to say that there is an infinite number of differences around and within the piece of chalk. There are differences between the chalk and the rest of the universe, between the chalk and the sun or the moon. And within the piece of chalk, there is for every molecule an infinite number of differences between its location and the locations in which it might have been. Of this infinitude, we select a very limited number, which be-come information. In fact, what we mean by information—the elementary unit of information—is a difference which makes a difference, and it is able to make a difference because the neural pathways along which it travels and is continually transformed are themselves provided with energy. The path-ways are ready to be triggered. We may even say that the question is already implicit in them. 

p460 (1987), p459 (1972)

[Carl Jung in Septem Sermones ad Mortuos, Seven Sermons to the Dead] points out that there are two worlds. We might call them two worlds of explanation. He names them the pleroma and the creatura, these being Gnostic terms. The pleroma is the world in which events are caused by forces and impacts and in which there are no "distinctions." Or, as I would say, no "differences." In the creatura, effects are brought about precisely by difference. In fact, this is the same old dichotomy between mind and substance. 

We can study and describe the pleroma, but always the distinctions which we draw are attributed by us to the pleroma. The pleroma knows nothing of difference and distinction; it contains no "ideas" in the sense in which I am using the word. When we study and describe the creatura, we must correctly identify those differences which are effective within it.

I suggest that "pleroma" and "creatura" are words which we could usefully adopt, and it is therefore worthwhile to look at the bridges which exist between these two "worlds." It is an oversimplification to say that the "hard sciences" deal only with the pleroma and that the sciences of the mind deal only with the creatura. There is more to it than that. 

First, consider the relation between energy and negative entropy. The classical Carnot heat engine consists of a cylinder of gas with a piston. This cylinder is alternately placed in contact with a container of hot gas and with a container of cold gas. The gas in the cylinder alternately expands and contracts as it is heated or cooled by the hot and cold sources. The piston is thus driven up and down. 

But with each cycle of the engine, the difference between the temperature of the hot source and that of the cold source is reduced. When this difference becomes zero, the engine will stop. 

The physicist, describing the pleroma, will write equations to translate the temperature difference into "available energy," which he will call "negative entropy," and will go on from there.

The analyst of the creatura will note that the whole system is a sense organ which is triggered by temperature difference. He will call this difference which makes a difference "information" or "negative entropy." For him, this is only a special case in which the effective difference happens to be a matter of energetics. He is equally interested in all differences which can activate some sense organ. For him, any such difference is "negative entropy."

p462-3 (1987), p461-463