From Stuart Henderson, Canberra, Australia
The “ultrafinitists” who seek to abolish the use of infinity in mathematics reminded me of the influential Dutch mathematician L. E. J. Brouwer, renowned for proving Brouwer’s fixed-point theorem. He went on to found an approach to mathematics that he called intuitionism, which included a rejection of the concept of actual infinity, though it admitted the idea of potential infinity. Intuitionism has since fallen into obscurity(9 August, p 28). Could the ultrafinitists be reinventing work of the past?
