The traditional definition of “knowledge,” first put forward by Plato, is a “justified, true belief.” That definition stuck for a few thousand years until Edmund Gettier wrote a famous paper in 1963. The eponymous “Gettier problems” outlined in the paper threw a wrench in the works for the field of epistemology, and philosophers have been trying to get things back on track ever since. In this episode we review some examples of Gettier problems and try to come up with our own responses. We also take a look at how elephants, Bruce Lee, Doctor Who, and Donald Rumsfeld help us understand how we know what we know.