Fresh Breezes in the Philosophy of Mathematics


Extracted from an article by Dr. Reuben Hersh in:
American Mathematical Monthly
August - September 1995, pp 590-591

Philosophies of Mathematics:

I like to compare philosophy of mathematics today to philosophy of science in the 30's and 40's. That subject was dominated by logical positivists: Rudolf Carnap and his friends of the ``Wiener Kreis'' (Vienna Circle). As a result of taking Bertrand Russell and Ludwig Wittgenstein too seriously, they believed they knew the correct methodology for scientific work: (1) state the axioms; (2) give correspondence rules between words and physical observables; (3) derive the theory, as Euclid derived geometry, or Mach derived mechanics.

It was noticed after a while that what logical positivists said had little in common with what scientists did or wanted to do. New ideas in philosophy of science came from Karl Popper, Tom Kuhn, Imre Lakatos, Paul Feyerabend. These subversives disagreed with each other. But they all thought philosophers of science could think about what scientists actually do, not bring presuppositions and instructions for scientists to ignore.

Philosophy of mathematics is overdue for its Popper, Kuhn, Lakatos, and Feyerabend. It's overdue for analysis of what mathematicians actually do, and the philosophical issues therein. In fact, this turn is taking place. Wittgenstein and Lakatos helped start it. In recent years Michael Polanyi, George Polya, Alfred Renyi, Leslie White, Ray Wilder, Greg Chaitin, Phil Davis, Paul Ernest, Nick Goodman, Phil Kitcher, Penelope Maddy, Michael Resnik, Gian-Carlo Rota, Brian Rotman, Gabriel Stolzenberg, Robert Thomas, Tom Tymoczko, Jean Paul van Bendegem, and Hao Wang have participated.

Here are some ideas some of these people hold.

  1. Mathematics is human. It's part of and fits into human culture. (Not Frege's abstract, timeless, tenseless, objective reality.)
  2. Mathematical knowledge is fallible. Like science, mathematics can advance by making mistakes and then correcting and recorrecting them. (This ``fallibilism'' is brilliantly argued in Lakatos' {\em Proofs and Refutations}.)
  3. There are different versions of proof or rigor, depending on time, place, and other things. The use of computers in proofs is a nontraditional version of rigor.
  4. Empirical evidence, numerical experimentation, probabilistic proof all help us decide what to believe in mathematics. Aristotelian logic isn't necessarily always the best way of deciding.
  5. Mathematical objects are a special variety of social-cultural-historical object. We can tell mathematics from literature or religion. Nevertheless, mathematical objects are shared ideas, like Moby Dick in literature, or the Immaculate Conception in religion.