Moreover, , and indeed Heidegger's philosophy in general, has been presented and engaged with by thinkers such as Dreyfus (e.g., 1990) and Rorty (e.g., 1991a, b) who work somewhere near the interface between the contemporary European and the analytic traditions.
A cross-section of broadly analytic reactions to Heidegger (positive and negative) may be found alongside other responses in (Murray 1978). In 1933 Heidegger joined the Nazi Party and was elected Rector of Freiburg University, where, depending on whose account one believes, he either enthusiastically implemented the Nazi policy of bringing university education into line with Hitler's nauseating political programme (Pattison 2000) or he allowed that policy to be officially implemented while conducting a partially underground campaign of resistance to some of its details, especially its anti-Semitism (see Heidegger's own account in ).
The reasons for this incompleteness will be explored later in this article.
One might reasonably depict the earliest period of Heidegger's philosophical work, in Freiburg (1915–23) and Marburg (1923–6), before he commenced the writing of itself, as the pre-history of that seminal text (although for an alternative analysis that stresses not only a back-and-forth movement in Heidegger's earliest thought between theology and philosophy, but also the continuity between that earliest thought and the later philosophy, see van Buren 1994, 2005).
The philosophical character of Heidegger's involvement with Nazism is discussed later in this article. Exactly when this occurs is a matter of debate, although it is probably safe to say that it is in progress by 1930 and largely established by the early 1940s.
If dating the turn has its problems, saying exactly what it involves is altogether more challenging.
Although he didn't leave the Nazi party, he did attract some unwelcome attention from its enthusiasts.
From this platform he proceeded to engage deeply with Kant, Kierkegaard, Nietzsche, and, perhaps most importantly of all for his subsequent thinking in the 1920s, two further figures: Dilthey (whose stress on the role of interpretation and history in the study of human activity profoundly influenced Heidegger) and Husserl (whose understanding of phenomenology as a science of essences he was destined to reject).In 1915 Husserl took up a post at Freiburg and in 1919 Heidegger became his assistant.Heidegger spent a period (of reputedly brilliant) teaching at the University of Marburg (1923–1928), but then returned to Freiburg to take up the chair vacated by Husserl on his retirement.For the young Heidegger, then, it is already the case that phenomenological analysis starts not with Husserlian intentionality (the consciousness of objects), but rather with an interpretation of the pre-theoretical conditions for there to be such intentionality.This idea will later be central to, and elaborated within, , by which point a number of important developments (explained in more detail later in this article) will have occurred in Heidegger's thinking: the Husserlian notion of formal ontology (the study of the a priori categories that describe objects of any sort, by means of our judgments and perceptions) will have been transformed into (a neo-Aristotelian search for what it is that unites and makes possible our varied and diverse senses of what it is to be); Husserl's transcendental consciousness (the irreducible thinking ego or subject that makes possible objective inquiry) will have been transfigured into (the inherently social being who already operates with a pre-theoretical grasp of the a priori structures that make possible particular modes of Being); and Husserlian intentionality (a consciousness of objects) will have been replaced by the concept of a god that one should respect—what unites all the different modes of Being is that they realize some form of presence (present-ness) to human beings.