L.E.J. Brouwer´s intuitionism: a revolution in two installments

There are two main periods in Brouwer´s foundational activities. The first one is covered by the dissertation of 1907 and subsequent papers. The second one starts in 1918 with the introduction of choice sequences. Both periods have their own specific characteristics. The first period is less mature, with a stronger critical component, the second is more the scholarly presentation of a program and its consequences. In this paper we will try to sketch the development of ideas and notions in both period and the technical realization of the foundational aspects. An extensive treatment of the topics of this paper will be published in a volume on “History and philosophical significance of proof theory”