Paper: Frequentism and Bayesianism: A Python-driven Primer (Jake VanderPlas)

This is the final version – ready to be reviewed.
"unknowable" helps because it emphasizes that often we don't care about the particular, true value of a parameter, but only the effect it has on our own experiments. That's particularly true in practice when using effective models, where the "true value" of the parameter likely has no real meaning.

This doesn't make that very clear though, so I think it can be removed.