Description:
<jats:p>The later Wittgenstein holds that the sole function of mathematical propositions is to determine the concepts they invoke. In the paper this view is discussed by means of a single example: Wittgenstein's investigation of the concept of a regular heptagon as used in Euclidean geometry (i.e., the Euclidean construction game with ruler and compass) and in Cartesian analytic geometry. Going on from some well-known passages in Wittgenstein’s <jats:italic>Lectures on the Foundations of Mathematics</jats:italic>, and completing these passages, it is shown that Wittgenstein’s view makes perfectly good sense and can be very well defended.</jats:p>