Tools For Detecting Rationale
This is a very broad subject. Philosophers have written volumes on this subject for thousands of years and have come up with various theories of knowledge. The following link might help with the overall picture: Epistemology | Stanford Encyclopedia of Philosophy Imam Farahi also presented his theory of knowledge. If you meant to ask a narrower question, please clarify.
@faisalharoon A bundle of gratitude sir. You were very patient and kind. I would definitely go through all the material you have shared. May Allah give lots of happiness