A good theory explains why something holds; it has as few moving parts as possible, each of which is critical to the explanation, and none of which can be sacrificed without doing great violence to the explanation. Moreover, a good theory is (usually) consistent with other good theories; good theories fit together in a sensible way. Furthermore, a good theory usually has greater reach than it was formulated to solve. That is, it solves problems that were thought to be unrelated to the original problem that the theory was meant to solve. For instance, the explanation that the seasons are caused by the tilting of the earth's axis is a good explanation. It explained the seasons in an elegant way that was straightforward and impossible to fiddle with without destroying the explanation; it also explained why opposite seasons prevailed in the northern and southern hemispheres.
Theory
Theory
Theory
A good theory explains why something holds; it has as few moving parts as possible, each of which is critical to the explanation, and none of which can be sacrificed without doing great violence to the explanation. Moreover, a good theory is (usually) consistent with other good theories; good theories fit together in a sensible way. Furthermore, a good theory usually has greater reach than it was formulated to solve. That is, it solves problems that were thought to be unrelated to the original problem that the theory was meant to solve. For instance, the explanation that the seasons are caused by the tilting of the earth's axis is a good explanation. It explained the seasons in an elegant way that was straightforward and impossible to fiddle with without destroying the explanation; it also explained why opposite seasons prevailed in the northern and southern hemispheres.