A reader writes:

The only metaphors that make sense are too graphic and cruel for popular use (domestic

FROGAndyLyons:Getty

violence is one example), because the "boiled frog phenomenon" is distinctly human, not animal, activity. Boiled frog scenarios depend upon a shared cognitive reality (he loves me, I need this job, the earth has always been this way) displacing or rendering moot an indisputable physical reality (he beats me, I can find a job that doesn't give me ulcers, the climate is changing). The great thing about the animals we surround ourselves with is that they don't tend to allow thinking to interfere with perceiving what's actually happening.

So what if it's untrue? Even if thousands of conceptual frogs are boiled daily, it's a useful way to talk about a human tendency that's otherwise impossible to talk about in rational, unloaded terms.

Fallows weighs in and Glenn Beck didn't actually kill a frog.