This is bad (overgeneralized) advice. Empirical claims do require skepticism (on, say, this arbitrary 0-10 scale), but logically deducible claims are true. Period. There is no doubt, counter-example, or possibility of being wrong. Mathematics is a good example of what I mean. Given, say, Peano's axioms, it follows that 1+1 = 2. That's it. I don't need a belief scale. There is no possibility that statement isn't true--it is. This is the problem with these bite-sized philosophy videos: they spout overgeneralized advice, often with needless similes (e.g. we need an analogy with a capacitor...to understand a scale), and it's mistaken for philosophy.