Science Quote by Michael Behe

Behe’s sentence is built like a trapdoor: accept one key premise, and the floor drops out from under Darwinian gradualism. The phrase “requires a function to select” sounds like a neutral technical point, but it quietly narrows what counts as an evolutionary pathway to only those with immediately selectable payoffs. That’s the rhetorical move: evolution is framed as blind to anything that isn’t already doing its final job.

Then comes the carefully lawyered hedge, “if there is such a thing.” Behe signals restraint while still smuggling in a loaded category: “irreducibly complex,” his signature term from the intelligent design debates of the 1990s (especially Darwin’s Black Box). It’s less an empirical description than a challenge condition: find a system whose parts are all necessary for its current function, and he argues incremental steps can’t get you there. The next clause, “would have to arise as an integrated unit,” presses readers toward a binary choice: either the system appears all-at-once, or natural selection is helpless.

The subtext is strategic. Behe isn’t merely offering a hypothesis about molecular machines; he’s trying to shift the burden of proof. If evolutionary biologists can’t narrate a stepwise route with selectable intermediates, the implication is that some other kind of cause is needed. Critics note the narrowness of the setup: parts can be selected for different functions (exaptation), scaffolding can be temporary, and “function” itself can be partial, messy, and context-dependent. But as persuasion, the line works because it turns complexity into a courtroom question: produce a plausible chain of utility, or concede a gap.