small example

Neverthless ,it is certainly the way that we have made progress in the past.the classic example again is the Newtonian theory of gravity which tells us that the gravitional force between two bodies depends only on one number associated with each body,its mass, but is other wise independet of what the bodies are made of .Thus one does not need to have theory of structure and constitutions of the sun and the planets in order to caluclate their orbits.