Hypothesis is guessing, or if you please starting a question. A phenomenon is observed having something peculiar about it. Rumination leads me to see that if a certain state of things existed, of whose actual existence I know nothing, that phenomenon would certainly occur, or at any rate, would in all probability occur. I say, By George, I wonder if that is not the very state of the case! That is hypothesis. The justification of my attaching the slightest weight to such a mere guess is, that there are just these three modes of inference, and neither Deduction or Induction can furnish me with any new idea. Unless I can get to the bottom fo things by hypothesis, I may as well give up trying to comprehend them. But not only that; but just as the general advantage of the inductive procedure admits of deductive proof, so induction in its turn shows that hypotheses have a very decent chance of turning out satisfactory, or at least answering well and being helpful for a long time.