Science Quote by Alfred Russel Wallace

Wallace is doing what great scientists do when they’re cornered by a bad objection: he changes the scale of the argument so the objection collapses under its own weight. The line is a rebuke to the claim that if we can’t fully explain the ultimate origins of natural processes, we’re barred from explaining complex outcomes built from them. His analogy is pointed: you don’t need a complete theory of metallurgy or plant development to recognize that steamships and railways have origins in human design, incremental tinkering, and intelligible chains of cause and effect. Ignorance of deeper “first causes” doesn’t erase the evidence right in front of you.

The subtext is a defense of historical inference, the kind Darwin and Wallace relied on when reconstructing evolution from fossils, biogeography, and variation. In the 19th century, critics often tried to force evolutionary theory into an impossible standard: explain life’s ultimate beginnings, or admit defeat. Wallace’s move is to expose that standard as selectively punitive. We accept partial knowledge in every other domain of explanation; we don’t demand a complete account of chemistry before allowing ourselves to understand engineering.

There’s also a tactical humility here. Wallace isn’t claiming omniscience about nature’s deepest laws; he’s insisting that workable explanations can be real without being total. The rhetorical strength comes from treating scientific reasoning as continuous with everyday reasoning: we infer origins from patterns, constraints, and traces. The target isn’t skepticism itself, but the kind that pretends to be principled while really just trying to veto unwelcome conclusions.