DISCUSSION 
intuition. Is there an intuitive prediction or is all prediction 
dependent upon extrapolation ? 
Mackay: My guess is that when we make an intuitive 
judgment we are not in fact working without data, but are 
processing data in our brains in a manner which the technician 
would call “analogue” rather than “‘digital’’. In other words, 
it is more like adjusting weights in a balance than manipulating 
discrete counters. If intuitive judgment is at all like this, it is 
not surprising that we are not aware of it in the way we are of 
discrete thought-processes. When a medical man, for instance, 
declares that he is using intuitive judgment, or is basing his 
judgment on experience as well as on present data, it seems 
possible that what he is doing is to allow his past experience and 
present observation to mould the weights given to his various 
explicit data. ‘The outcome of the process can therefore be more 
faithful to fact; but it is still a form of extrapolation. 
Medawar: I think there is a danger of a mystique growing 
up around the process of diagnosis. I do not think there is any 
difference between a clinical diagnosis and any other kind of 
hypothesis devised by scientists, except that a diagnosis is a 
hypothesis relating to a particular patient on a particular 
occasion. There is the same element of the intuition in it as 
there is in any other act of hypothesis- making, and to pretend 
that there is something more is, I think, pure mystique. 
Brock: Jam in full agreement with ‘this, 
MacKay: ‘There is one important difference between 
hypothesis-making in medicine and law and hypothesis-making 
in other sciences. Part of the data that a clinician uses is his 
knowledge of what it 1s like to be a man. ‘This may be used just 
as rationally as other data, although it happens to be inter- 
nalized and unverbalizable, whereas in most other sciences we 
are able to verbalize all our data. I hope nobody wants 
irrational mystique; but I think it is important to recognize this 
distinction between judgments in human affairs and hypotheses 
in the more exact sciences. 
Medawar: Wuxley claimed that no machine could really 
devise a hypothesis and he gave the example of a brilliant 
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