Philosophers and mathematicians reacted in various different ways to this situation (= the discovery of Russell's parados). Poincare, who disliked mathematical logic and had accused it of being sterile, exclaimed with glee, 'it is no longer sterile, it begets contradiction'. This was all very well, but it did nothing towards the solution of the problem.
Source: My Philosophical Development, chap. 7：1959．
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