How Many Ways Are There to Win at Sandwalk?

At University of Toronto professor Laurence Moran's blog Sandwalk, named for Darwin's famous "thinking path," I've followed a discussion of the evolution of de novo chloroquine resistance by malaria (which I wrote about here). The exchange has touched on a few issues that seem to confuse people easily.

One is how we should view the probability of winning something. In questioning my malaria numbers, a commenter remarked that it's misleading to focus retrospectively on a single event, such as...