In her 1979 paper “Cognitive Repression in Contemporary Physics”, Evelyn Fox Keller describes the scientific viewpoint associated with classical (i.e. Newtonian) mechanics as based on a pair of conjoined assumptions. Firstly, that the subject of scientific knowledge is strictly separable from the possible objects of such knowledge; and secondly, that it is possible to establish a direct correspondence between what is known of each such object and its actuality. According to this viewpoint, “nature” is both objectifiable and ideally knowable by a scientific subject which stands apart from that nature in order to observe it.
We have here an operation of dividing-and-regluing very like that described by Laruelle as characteristic of philosophy
(and, indeed, Laruelle would likely describe Fox Keller’s account as true of a certain philosophy-of-science, or philosophical epistemology, rather than of science itself as a practical stance). The immanent Real is split into an objectifiable domain of distinct entities, and a transcendental order of knowledge which proposes to organise those entities into a world (“the scientific worldview”, let’s say). Rather than thinking “according to the Real”, or from the premise that both “knower” and “known” are immanent to the same reality (and thus share a fundamental identity), the stance Fox Keller describes is “decisional” in Laruelle’s sense: it begins by making a cut, and by giving itself the authority to repair that cut.
Fox Keller observes that the principles of objectifiability and knowability break down in the face of quantum mechanical phenomena: they cannot be maintained simultaneously, and every attempt to do so produces metaphysical monsters in the guise of “interpretations” of quantum mechanics (as Derrida once put it: coherence in contradiction indicates the force of a desire). Her Piagettian reading of the resistance
to non-classical epistemology in terms of affective positions is suggestive (in that smug “clever men in white coats are really just big babies” sort of way that has never quite seemed to go out of vogue, for reasons I could probably venture some pseudo-psychological explanations for myself), but doesn’t particularly help us resolve the problem of how to develop such an epistemology.
Susskind describes the situation as follows: in a classical system, we are confident of always being able to make a “gentle enough” measurement that the system being measured is not perturbed: the apparatus is able to determine how the system would behave if the apparatus itself were not present. This is, in fact, perfectly possible a lot of the time. Within a quantum system, however, measurement is carried out by means of operations* which participate in the total behaviour of the system itself, such that we are always observing the outcome of what I will call an effectuation. Any such effectuation is the effectuation both of a measurement and of a new state of the system. Both (classical) objectifiability and (classical) knowability are untenable under these conditions; the former because the apparatus of measurement is not strictly separable from the system being measured, and the latter because the process of obtaining information about one aspect of the system may render information about another aspect inaccessible.
This is helpful, but doesn’t go quite far enough. If we had not measured the particle’s position, we should have been able to measure its momentum (and vice versa); but this does not mean that, at some moment prior to measurement, the particle necessarily had
both position and momentum (i.e. possessed some complete, if hidden, state in which both position and momentum were simultaneously inscribed). Rather, measurement-of-position and measurement-of-momentum are distinct operations that effectuate one value at the expense of being able to effectuate the other.
A thoroughgoingly immanent account of how science proceeds will be one which sees scientific theory-building, measurement and knowledge-formation as effectuations of the same Real, rather than the work of one kind of agent – the detached scientific knower – upon one kind of patient – “Nature”, etherised upon a table. That is one way of looking at the problematic with which Laruelle is engaged, and of understanding why the “quantum” has taken on such a totemic significance for him in his later work.
- As Susskind also reminds the reader, an operator
is a mathematical entity, which acts on state vectors to produce new state vectors. It does not, however, change physical reality – rather, it describes how a real-valued measurement is derived from a state vector in a quantum system. How the state of that system changes in the process of carrying out the measurement is a quite different matter. Accordingly, I have corrected “operator”, where it appears above, to “operation”. Caveat lector, as always when I’m trying out new stuff.