Quacks Like a Duck — String Theory and the Duck That Wasn't
The duck test is one of the cleanest heuristics in the epistemological toolkit: if it walks like a duck and quacks like a duck, treat it as a duck. It works because surface signs are usually entangled with underlying causes. Ducks walk the way they do because of their anatomy; they quack because of the shape of their bill. The surface and the substance are not independent. When you correctly read the surface, you have usually correctly identified the substance underneath. ...