This past year at the Global Atheist Convention in Melbourne, famed American cognitive scientist, philosopher and atheist, Daniel Dennett, delivered a speech entitled “How to Tell You’re an Atheist.”

Dennett, along with Richard Dawkins and the late Christopher Hitchens, might best be described as the Holy Trinity of atheism. Where Hitchens was a brilliant, militant and supremely eloquent orator, able to logically eviscerate believers left and right, and Dawkins was the scientist provocateur of the three, Dennett has been the more subtle tactician, combining the best of Hitchens and Dawkins without as much attention.

Dennett looks rather like a hybrid of a college philosophy professor and Santa Claus dressed in business-casual attire, which works to his favor: his grandfatherly, non-confrontational approach might be better able to convince the faithful to entertain atheism than Dawkins and Hitchens’ militancy.

Dennett begins the speech by talking about Anton Syndrome, in which people lose their sight but deny that they are blind; which leads quite naturally into matters atheism and theism. Dennett also references the Concorde Fallacy, or sunk costs, “when you’ve invested most of your life in something, turning away from that and deciding that that was not a good investment is very hard to do.”

Watch Dennett deliver his informative but whimsical speech below. Note the Pixies “Where Is My Mind?” as Dennett approaches the dais.