All models are wrong, but some are useful

All models are approximations. Assumptions, whether implied or clearly stated, are never exactly true. All models are wrong, but some models are useful. So the question you need to ask is not "Is the model true?" (it never is) but "Is the model good enough for this particular application?"

George Edward Pelham Box, Alberto Luceño e Maria Del Carmen Paniagua-Quinones, "What Can Go Wrong and What Can We Do About It?" in Statistical Control by Monitoring and Adjustment (2nd Edition), 61.