# L. E. J. Brouwer

**Luitzen Egbertus Jan Brouwer** ForMemRS (27 February 1881 – 2 December 1966), usually cited as **L. E. J. Brouwer** but known to his friends as **Bertus**, was a Dutch mathematician and philosopher, who worked in topology, set theory, measure theory and complex analysis.

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## Quotes[edit]

- The viewpoint of the formalist must lead to the conviction that if other symbolic formulas should be substituted for the ones that now represent the fundamental mathematical relations and the mathematical-logical laws, the absence of the sensation of delight, called "consciousness of legitimacy," which might be the result of such substitution would not in the least invalidate its mathematical exactness. To the philosopher or to the anthropologist, but not to the mathematician, belongs the task of investigating why certain systems of symbolic logic rather than others may be effectively projected upon nature. Not to the mathematician, but to the psychologist, belongs the task of explaining why we believe in certain systems of symbolic logic and not in others, in particular why we are averse to the so-called contradictory systems in which the negative as well as the positive of certain propositions are valid.
- as translated by Arnold Dresden from: Brouwer, L. E. J. (1913).
*Intuitionism and formalism*. Bulletin of the American Mathematical Society, 20(2), 81–96. (quote on p. 84)

- as translated by Arnold Dresden from: Brouwer, L. E. J. (1913).

## Quotes about Brouwer[edit]

- In 1908 Brouwer introduced for the first time "weak counterexamples", for the purpose of showing that certain classically acceptable statements are constructively unacceptable (Brouwer 1908). Too much emphasis on these examples has sometimes created the false impression that refuting claims of classical mathematics is the principle aim of intuitionism.
- A. S. Troelstra and D. van Dalen in: Constructivism in Mathematics, Vol. 2, Elsevier (1988), pp. 8–9