Abstract: Popular discussion of utopian possibilities and apocalyptic risks from new technologies is sometimes dismissed as ungrounded millennial hysteria. In this essay I reflect on the various types of historic, pancultural millennialism. I then suggest how contemporary forms of secular techno-utopian and techno-apocalyptic discourse reflect these millennialist types and their characteristic biases to over- or under-estimate catastrophic risks, and adopt fatalistic or inappropriate stances toward risk reduction. Then I suggest that awareness of these characteristic millennialist cognitive biases help us separate grounded assessments of catastrophic risks from their attendant psycho-cultural baggage. By carefully parsing our hopes and fears about the future from the characteristic dysfunctions of millennialism we can tap millennialism’s energy without being led astray by it. (Download the PDF)