Richard Wolin on the Frege comparison.
That philosophy and political conduct stand in necessary association with one another is by no means a self-evident truth in the annals of cultural history. An apparent refutation of their causal relation that is often cited is the case of the logician Gottlob Frege, who also happened to be a virulent anti-Semite. Certainly, we are instructed, Frege's anti-Semitism in no way redounds to the discredit of his logical theories. Nor can it in the least be claimed, conversely. that those theories contain the seeds of his anti-Semitism. To be sure, we may well hold Frege the historically existent individual in less esteem as a result of our awareness of his prejudicial sentiments. But it stands beyond doubt that in his case phiIosophy and life-conduct lie at a safe remove from one another.
Why should things be any different in Heidegger's case? Because Of the nature of his philosophy itself. One of the essential components of Heidegger's philosophy is the claim that Being and Time stand in necessary relation to one another, that Being itself contains an inalienable temporal dimension. As a "philosophy of existence," this means that the drama Of being human—Dasein's "factical' coming to presence—not only occurs in history, but is itself historical.
This is confused. Time, as investigated in Being and Time, temporality, is different from historical time, which began to preoccupy Heidegger a decade later. A dasein's historical time is contingent. Daseins at different times, in different cultures, might have different understandings of being. On the other hand, Ereignis, the appropriative moment that makes beings for dasein is always already going on; for daseins in igloos a millennium ago and for a cosmopolitan hipster in front of a screen today. After excursions down the paths of historical thinking, Heidegger reemphasized the universal nature of Ereigis in his seminars in the sixties. The ontology that makes beings possible, also makes logic, maths, science, and art possible. Either ontology is something universal, allowing for a logical understanding of beings that is also universal, or ontology is historically contingent, in which case Frege and modern logic must be contingent.