The successive versions [of the program] appear as successive levels of elaboration. It is apparently essential for each level to make a clear separation between what it does and how it works. The description of what it does, the definition of its nett effect, requires introduction of the adequate concepts, and both examples seem to show the way in which we can use power of abstraction to reduce the appeal to be made upon enumeration. (E.W. Dijkstra - Stepwise Program Construction. EWD227, February 1968) Scientific thought includes intelligent thinking [...]. A scientific discipline emerges with the - usually rather slow! -- discovery of which aspects can be meaningfully studied in isolation for the sake of their own consistency -- in other words, with the discovery of useful and helpful concepts. Scientific thought includes in addition the conscious search for useful and helpful concepts. (E.W. Dijkstra - On the Role of Scientific Thought. EWD447, August 1974)

By: Haim Kilov and Ian Simmonds

Published in: RC20544 in 1996

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