2011-10-02
Explanation
This comic reimagines the childhood game of "playing doctor" -- where kids innocently examine each other -- as "playing Doctor of Philosophy." A girl asks a red-haired boy named Bobby if he wants to play Doctor of Philosophy. He agrees. She then says, "I'''ll show you mine, a posteriori, if you show me yours, a priori." Bobby replies, "Okay, but only if you can show a definite causal link between the two events."
The terms "a posteriori" (knowledge derived from experience/observation) and "a priori" (knowledge derived from reason alone, independent of experience) are fundamental concepts in epistemology. The girl is playfully offering an exchange of empirical and theoretical knowledge. Bobby'''s demand for a "definite causal link" raises the stakes to a higher philosophical standard. The girl responds, "That'''s easy: it'''s happened that way every time in the past." Bobby reluctantly accepts with "...okay, fine." But as he walks away, the girl runs off shouting, "Fool! Induction is impossible!" Bobby cries, "Hey! No fair!"
The punchline references the Problem of Induction, famously articulated by philosopher David Hume: just because something has happened consistently in the past does not logically guarantee it will happen in the future. The girl tricked Bobby by offering inductive evidence (past experience) as her causal link, then pulled the rug out by invoking the philosophical critique of induction itself. The votey panel shows the girl contentedly reading a book by David Hume, saying "So practical!" -- an ironic comment since Hume'''s philosophy is famously impractical in everyday life, yet the girl found a very practical use for it: winning a game against Bobby.