Now, my attack is not against everyone who finds Heidegger helpful (some of my best friends are heideggerians!). And it is probable that if you mostly read Heidegger for the metaphysics, you might not need to take seriously his fascism (maybe). However, there exists Heideggerian environmental philosophy, Heideggerian Left political philosophy, Heideggerian ethics, etc. If you want to engage Heidegger for politics and ethics, you are going to have to seriously deal with his fascism. Not brush it aside, excuse it, call it lamentable or naive, but face it head on. And doing so means confronting the fact that Heidegger's political comments are not somehow exterior to his philosophy, but are throughly bound up in his fascism. The Chronicle article is very strong here (in a few other places, less so):
Moreover, many of Heidegger’s key concepts appear to overlap with those of fascism—though experts have never, until perhaps now, seen them linked explicitly to Jews. For example, the philosopher is scathing in his criticism of modernity’s wayward drift, the soullessness and ahistoricity of the cosmopolitan, and the rule of technology and science. He believed that the answer to this crisis of civilization lay in the revolutionary empowerment of the ethnic nation, or Volksgemeinschaft. And not just any Volk could pull mankind off its destructive path, but rather specifically the German Volk.This is very much the argument of Charles Bambach's excellent (if sympathetic) book, Heidegger's Roots. As Deleuze and Guattari said in A Thousand Plateaus, "We're tired of trees. We should stop believing in trees, roots, and radicles. They've made us suffer too much." Understanding Heidegger means understanding that his fears of the anonymous other, of free floating intelligence, and of rootless peoples are fears that bound up in a particular kind of fascism. It doesn't mean it has to be fascist, but you can't ignore that connection, either. It also means understanding Heidegger's idea of what it means to be a philosopher, and the importance of philosophy (later, of thinking), is bound up with its own vision of hierarchy and authenticity. Perhaps Heidegger is most fascist in his conception of what it means to do philosophy itself.
"We regularly see terms in Heidegger’s work like das Volk, ‘homelessness,’ ‘uprootedness,’ and ‘worldlessness,’" says Florian Grosser, a Heidegger expert in the philosophy department of the University of St. Gallen, in Switzerland. Such terms, he notes, were the standard vocabulary of Europe’s anti-Semitic right, regularly applied to Jews. But in Heidegger’s published work, "it’s not Jews he’s talking about, but rather the fate of modern man. So, if indeed he goes further in the notebooks, Mr. Grosser says, "we’re going to have to look at exactly how he connects these concepts to Jews. It could be very problematic."
And we need to be careful in understanding his thinking. It has become common to claim that the critique of biopolitics is rooted in Heidegger, particularly his critique of en-framing (see, variously, Nancy, Campbell, and Wolfe. All excellent books, regardless of my next point). I understand where this is coming from, but we cannot disassociate Heidegger's critique of technology and en-framing from his broader commitments with those critiques. Specifically, his critique of technology and en-framing are based in a broader commitment to authenticity, particularly authenticity around death. This understanding of authenticity is the very thing that makes the Holocaust itself unthinkable for Heidgger (for this argument, see Todd Presner's Mobile Modernity, chapter six, "Auschwitz." He is really good on this argument, and I wish I had seen this book while writing "Beyond Biopolitics"). I would add to Presner's argument that Heidegger's critique of technology and en-framing is also connected to his divide between the human animal and other animals. In other words, rather than critiquing en-framing being the beginning of understanding the biopolitical, it replicates the biopolitical by by advocating for the proper and authentic disposition of bios.