MY FLOWCHART FOR DECIDING IF SOMETHING IS TRUE

1. FOUNDATION CHECKS - try to make a list of why you think The Idea is true, and check the veracity of each foundational mini-idea which comprises The Idea. Google works pretty good if you can figure out how to ask the right questions. Also in this step think hard about how you arrived at The Idea: When and where is the first time you remember thinking it, did somebody else tell you it was true or have you spent time developing it entirely?
2. DEDUCTION NOT INDUCTION - go back and think about your life and think of situations in which you saw The Idea play out. Try to confirm that you have a lot of data-points for The Idea. A true idea will be visible in many different iterations, places on earth, times humans have been alive, situations large and small, etc. What experiences have you had that led to the inception of The Idea? Also try to think of situations when The Idea is not true, and see if you can further refine The Idea itself. Do that lingusitics thing, "what is a chair? What is not a chair? Why did The Idea play out here but not there?"
3. CHECK YOUR EGO - because our brains do not give us a perfect representation of the world around us, and because our ego wants to preserve itself at any cost, we have to think about why The Idea exists; does it allows us to avoid unpleasant thoughts or things, or if The Idea somehow gives us pride or correctness or intelligence over others -then its probably not true, just a pleasant thought. This part is about dissecting away your personal investment in The Idea from the true veracity of The Idea.
4. TALK TO OTHERS - talking to people about The Idea serves several purposes: (a) to double-check all of your computations. (b) to get more data on the problem or issue in general. (c) It also serves to refine your concept of The Idea: The idea is more likely to be true if it can be explained clearly, multiple ways, and expressing it out loud to someone else tends to force us to get to the most succinct version.
5. DEVILS ADVOCATE - think about why The Idea might not be more widely accepted, 'follow the money' to see who benefits if The Idea is true or false. Identify at least three reasons why The Idea might not be true, and see if any of those can fail to be disproven.