hypothetical deductive theory (logical deductive)
A theory consisting of postulates and theorems. Postulates are assumptions that cannot be verified directly; theorems are deduced from the postulates, and they can be verified experimentally. if an experiment designed to test a theorem comes out in the predicted direction, its postulate is indirectly verified, and the theory gains strength. If the experiment does not come out in the predicted direction , the theory loses strength. A hypothetical deductive theory is consistently changing in light of experimental evidence.