Thomas Kuhn, in The Structure of Scientific Revolution, refuses the cartesian philosophical paradigm because he separates observational stiumulus from interpretation and from sensation/interpretation itself (see Kuhn [1962], pp. 120- 135). Is it correct, in other terms, to argue that Descartes identifies stimulus, sensation/perception and interpretation, whereas Kuhn separates the three elements, by considering them three different processes?

If yes, can we say the following? ---->

a) for Kuhn stimulus and sensation/perception are two different unconscious processes, whereas interpretation is the only deliberative one.

b) Descartes identifies stimulus and interpretation because he doesn't care about the fact that stimulus and sensation/perception are unconscious processes but interpretation is a deliberative one.

  • 2
    The issue is with the so-called Theory-ladenness of observations : " observations are said to be "theory‐laden" when they are affected by the theoretical presuppositions held by the investigator. " The main source of this view is Norwood Russell Hanson with his work Patterns of Discovery (1958) (see SSR, footnots page 27,78,113). Sep 24, 2018 at 11:16
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    Regarding Kuhn, see Postscript to SSR (p.195) : "What I have been opposing in this book is therefore the attempt, traditional since Descartes but not before, to analyze perception as an interpretive process, as an unconscious version of what we do after we have perceived." And p.196 : "But talk like this of seeing and sensation here also serves metaphorical functions as it does in the body of the book. We do not see electrons, but rather their tracks or else bubbles of vapor in a cloud chamber. We do not see electric currents at all, but rather the needle of an ammeter or galvanometer." Sep 24, 2018 at 11:23
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    "I have repeatedly acted as though we did perceive theoretical entities like currents, electrons, and fields, as though we learned to do so from examination of exemplars, and as though in these cases too it would be wrong to replace talk of seeing with talk of criteria and interpretation. The metaphor that transfers 'seeing' to contexts like these is scarcely a sufficient basis for such claims. In the long run it will need to be eliminated in favor of a more literal mode of discourse." Sep 24, 2018 at 11:24
  • Conclusion : Kuhn has no "theory of mind" or of perception in place, as opposed to Descartes' one. He his speaking "metaphorically", in the absence of a scientific theory of perception. Sep 24, 2018 at 11:25
  • thank you for your useful and helpful comments @MauroALLEGRANZA!
    – franz1
    Sep 24, 2018 at 15:07

1 Answer 1


See Descartes and the Pineal Gland :

In the Treatise of man, Descartes did not describe man, but a kind of conceptual models of man, namely creatures, created by God, which consist of two ingredients, a body and a soul. “These men will be composed, as we are, of a soul and a body. First I must describe the body on its own; then the soul, again on its own; and finally I must show how these two natures would have to be joined and united in order to constitute men who resemble us”

The bodies of Descartes’ hypothetical men are nothing but machines [...]. The working of these bodies can be explained in purely mechanical terms. Descartes tried to show that such a mechanical account can include much more than one might expect because it can provide an explanation of “the digestion of food, the beating of the heart and arteries, the nourishment and growth of the limbs, respiration, waking and sleeping, the reception by the external sense organs of light, sounds, smells, tastes, heat and other such qualities, the imprinting of the ideas of these qualities in the organ of the ‘common’ sense and the imagination, the retention or stamping of these ideas in the memory, the internal movements of the appetites and passions, and finally the external movements of all the limbs”

Thus, we have stimuli : "the reception by the external sense organs of light, sounds, smells, tastes, heat and other such qualities", and perception : "the imprinting of the ideas of these qualities in the organ of the ‘common’ sense and the imagination".

The pineal gland played an important role in Descartes’ account because it was involved in sensation, imagination, memory and the causation of bodily movements. [...] He explained perception as follows. When the sensory organs are stimulated, [...] image of the sensory stimulus appears on the surface of the pineal gland. It is this image which then “causes sensory perception” of whiteness, tickling, pain, and so on.

“It is not [the figures] imprinted on the external sense organs, or on the internal surface of the brain, which should be taken to be ideas—but only those which are traced in the spirits on the surface of the gland (where the seat of the imagination and the ‘common’ sense is located). That is to say, it is only the latter figures which should be taken to be the forms or images which the rational soul united to this machine will consider directly when it imagines some object or perceives it by the senses”.

Imagination arises in the same way as perception, except that it is not caused by external objects.

I think that "interpretation" is not part of Descartes' theory of mind.

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