No safe defense
In this crazy world, there's no simple procedure you can follow, no finite checklist or fixed ritual you can obey to ensure that your reasoning has been defensible and your actions just. There is a sense in which you are never safe. There's no one you can trust; the full force of your skepticism must be applied to everything. It may be tempting to seek out some authoritative book, like the Bible, or the Feynman Lectures on Physics, and trust that everything in the book is true. But the book is only probabilistic evidence about the state of the world, however strong. Authorities can be trusted exactly as much as a rational evaluation of the evidence deems them trustworthy, no more and no less.