Deductive reasoning is a scientific method that uses deduction to check or test theories and hypothesis.
Deductive reasoning consists of three steps, premise one, premise two and an inference. For Example, Premise one is all men are mortal, premise two is Sampson is a man. Thus, we infer that Sampson is a mortal.
Deductive Reasoning is the foundation of research and academic research in specific. In academic research we first make claims, gather data, and then test the claims or to be specific the hypothesis.
Inductive Reasoning makes broad claims about an observation. Data is gathered and then conclusions are drawn making it opposite to deductive reasoning.
The main difference between the two forms of reasoning is that deductive makes claims based on theory while inductive makes claims based on observations.
The main way that the two are used in the Lean six sigma world is inductive reasoning is used in Gemba walks and “management by walking around”, where the practitioner is observing the processes and then making decisions. While the entire DMAIC process under six sigma would be grouped under deductive reasoning as the practitioner theorizes a result, gathers data and tests if their results hold true.