Reviewing Thomas Kuhn’s ‘The Structure of Scientific Revolutions’ – Postscript

Kuhn’s postscript was written 7 years after the publication of his book. In the postscript he addresses many of the criticisms that have been raised against ‘The Structure of Scientific Revolutions’ and it is therefore important for those wanting to come to a better understanding of his seminal work. Having written this over 7 years Kuhn had a great deal of time to reflect on the criticisms levelled against his book and to further refine his understanding which is evident from the text. Kuhn’s work is subtle enough but condensing 7 years of reflection on the responses to his work means that the postscript is dense with complex ideas and I don’t think it is meaningful to say that it can be or should be easily summarised. The strength of Kuhn’s work is not that it is didactic but that it relies on the reader to engage with the material.

Kuhn proceeds to move through the main criticisms of his texts. Paradigms are a starting point for the postscript. Kuhn explains that the term paradigm has different meanings for him which he utilises in his book. Indeed one of these meanings is associated with a great deal of controversy.  He writes that a scientific community have received a standardised training. Different schools settle their competitions quickly and professional opinion is ‘unanimous’. These communities are the units for creating paradigms but paradigms are not essential for the development of an ‘isolated’ community. Indeed in this sense, the scientific community consists of a global community of scientists which is then narrowed down into specialised scientific communities. This is brought home when Kuhn tells us that there was no physics community before the mid-nineteenth century when it was preceded by an intersection of philosophy and mathematics. Kuhn also notes that theories of matter were under discussion by a number of different communities.

Kuhn describes the transition that occurs during a paradigm change. Revolution is a special renegotiation of relationships within a community which might consist of a small number of people.  Crises can be generated by groups other than those that experience them. Kuhn suggests that his description of paradigm is vague and develops his argument with the use of a disciplinary matrix. In the disciplinary matrix, there is the symbolic representation, the shared belief and the values of the scientific community.

Are Kuhn’s Assertions Supported or Challenged by 21st Century Neuroscience?

In the postscript, Kuhn discusses visual perception. Are the sensations of two viewers the same? There is a lot of processing involved in becoming aware of sensations with different pathways from stimulus to sensation. I think perhaps it is easier to talk about perception than sensation which occurs at an earlier stage in the process. Kuhn is therefore asking us to consider whether two people or communities with their different backgrounds would experience the same perceptions of identical stimuli as though they are living in ‘different worlds’. These different groups are of course the different scientific communities with their different models of phenomenon. Kuhn’s arguments aren’t meant to be interpreted in a concrete way but I thought it was a useful example of how Kuhn’s material can be engaged. There was a recent study by Gallant and colleagues from 2011 which I thought was a really great study (see review here). I won’t go into it in too much detail but will summarise it by saying that the researchers were able to correlate the activity in one brain region – the visual cortex with moving images witnessed by their subjects. They were then able to reconstruct witnessed moving images on the basis of the brain activity alone.

Reconstruction of Video Images in Gallant’s Lab

Video Reconstructions of Clips Presented to 3 Subjects. The average of the best-fit clips is on the left, while those on the right are the best fit clips. Each row represents a single subject.

In the second video, the reconstructions from 3 subjects can be seen. Above the 3 rows is the video that was shown to the three subjects. Then there are three rows each of which corresponds to a subject. The first video in the row represents the video that was reconstructed from that subject’s brain activity by the software. The remainder of the videos on the row are those witnessed by the subject which were the nearest matches and which were averaged out to reconstruct the video. What is meant by ‘nearest matches’ is that the brain activity of the subject when witnessing those videos was similar to the brain activity when they were the test video. By this means the researchers approximated the video clip that the subject was watching and in effect were able to reconstruct the video the subject was watching on the basis of their brain activity alone – a quite remarkable achievement.

In returning to the question posed by Kuhn it is clear that each subject’s reconstructions draws parallels with different sets of images that they had been exposed to. The software algorithm selected different movie clips for each subject to approximate the pattern of brain activity that was generated when they viewed the clip of interest. Unfortunately there is a limit to how much we can infer from these results particularly as these results are also a function of the software algorithms that were being used. However we can use these results to comment on Kuhn’s analogies in several ways. Firstly we can say that Kuhn may indeed be correct in assuming that different people perceive the same stimulus on the basis of different past experiences and this is why the 3 subjects in the second video appear to be drawing on different previously witnessed video clips (remember though that this may be an artefact of the software). However we may also say that regardless of the previous experience, the subjects are operating in the real world and this is an important constraint. Subjects can use as many prior experiences to shape their perception of the stimulus as they want but unless they get their perceptions right in certain important ways, they’ll be walking into the proverbial lampost. Finally we can also say that the perceptions that appear to be occurring here are doing so in real time and in some ways are perhaps still at a fairly low level in the perceptual apparatus. The filtering is almost immediate and doesn’t suggest the type of rich context and abstract reasoning qualities we might associate with some of Kuhn’s concepts. The visual cortex ‘wants’ to discern form, colour and motion. Kuhn’s scientists want to discern the world constrained by the limits of a model built of multiple logical inferences and empirical observations. However the point is that Kuhn has powerfully invoked the inner experiences of the scientist and once this is granted, the subsequent discussion must become entangled in questions about conscious experience, about the very nature of the mind. Nevertheless the question of science is inextricably linked to questions about mind since science is a function of the mind. Although a set of laws may quite correctly describe certain features of the universe, it is only through the mind that these laws become alive. Without the mind they are objects – ink on paper, etchings on stone or electrons passing through circuit boards. And to become alive in the mind, the laws, the whole corpus of science must negotiate the mind in order to become alive and relevant in the world. Appealing to the mind is part of the package of science whether it is recognised or not.

Incommensurability, Puzzles and Values

If I was to read Kuhn’s postscript next week I would probably write a very different review because of the way in which his material must be engaged. For this review there were a few concepts that grabbed my attention. Kuhn talks about incommensurability. This is the phenomenon through which scientists from different communities have models which explain the same phenomenon but which entail different incompatible languages. This is one phenomenon for which Kuhn appears to have been criticised vociferously. Ironically he is clear that his concept has not been understood – Kuhn’s science has been labelled as subjective or suggesting that there is no ‘truth’ in science. However we may say that Kuhn and his critics models of science are incompatible. Part of this incommensurability arises from science as a function of the community. Kuhn talks about puzzle solving which was a key feature of his work. Kuhn’s idea is that the there is normal and revolutionary science. Once the revolution in science has occurred, the puzzle solving of normal science takes place. I like Kuhn’s framing of the puzzle as a ‘group licensed’ way of seeing the world. Finally I thought Kuhn’s further discussion of values was interesting. Kuhn asks us to consider what would happen if consistency was not a value in science. At such times it is clear that science can be deconstructed in a more profound way and that such analysis could even result in a more productive reconstruction. Kuhn’s work is a Magnus Opus, an illustration of the rewards of the seemingly abstract discipline of historical analysis which shows that looking closely at what has gone before can light the road ahead.


Thomas Kuhn. The Structure of Scientific Revolutions. Narrated by Dennis Holland. (Paperback originally published in 1962). Audible. 2009.


For a review of the Introduction see here.

For a review of Chapter 1 see here.

For a review of Chapter 2 see here.

For a review of Chapter 3 see here.

For a review of Chapter 4 see here.

For a review of Chapter 5 see here.

For a review of Chapter 6 see here.

For a review of Chapter 7 see here.

For a review of Chapter 8 see here.

For a review of Chapter 9 see here.

For a review of Chapter 10 see here.

For a review of Chapter 11 see here.

For a review of Chapter 12 see here.

For a review of Chapter 13 see here.

In Support of Method – Critique of Feyerebend’s ‘Against Method’ see here.

An index of the site can be found here. The page contains links to all of the articles in the blog in chronological order. Twitter: You can follow ‘The Amazing World of Psychiatry’ Twitter by clicking on this link. Podcast: You can listen to this post on Odiogo by clicking on this link (there may be a small delay between publishing of the blog article and the availability of the podcast). It is available for a limited period. TAWOP Channel: You can follow the TAWOP Channel on YouTube by clicking on this link. Responses: If you have any comments, you can leave them below or alternatively e-mail Disclaimer: The comments made here represent the opinions of the author and do not represent the profession or any body/organisation. The comments made here are not meant as a source of medical advice and those seeking medical advice are advised to consult with their own doctor. The author is not responsible for the contents of any external sites that are linked to in this blog.


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