I recently encountered a critique of Arthur Lovejoy's well-known book on the "great chain of being." I've discussed that book in this blog , focusing on what it says about theodicy, that is, efforts to justify the ways of God to man. But the critic I encountered recently, Jaakko Hintikka, the fellow portrayed here, focuses on the "principle of plenitude." So let's look at that for a moment, gentle reader. The P of P is one of the "unit ideas" in Lovejoy's account of the great chain. It is one of the atoms that came together to form that molecule. In Lovejoy's formulation, the P of P is the idea that every kind of creature that is possible is also actual. In one form, this means that in the fullness of time, anything that is not the case now either once was the case or at some time will be the case, as when Descartes wrote that due to the laws of nature "matter takes on, successively, all the forms of which it is capable....