Karl Popper is a landmark figure in the philosophy of science.  His notion of “falsifiability” endures to this day and even appears in arguments about creation versus evolution.  But what does it mean for a theory to be falsifiable? And where does the idea stand in contemporary philosophy of science?  John and Ken test a few ideas on Popper and falsifiability with their Stanford colleague Denis Phillips, author of The Social Scientist’s Bestiary: A Guide to Fabled Threats to, and Defences of, Naturalistic Social Science.