You and I both know for the vast majority of people, this isn't possible. They just have to believe what someone else says.
I also know that you know, as important as doing the Math is, knowing what numbers to work with is at least as important.
Either of us could do the Math in 90+% of the other's field, but wouldn't know what assumptions/theory to use to get to the Math.
I have to believe someone's numbers in Finance, you have to believe that plane really will fly.
I always remember my second year of college I had a lab partner in an EE course that asked me "Which formula do I use for this problem?" I looked at him and said "That IS the problem. Once you know that, a monkey could take it from there." Now with the computers and software available, that's even more true than it was 50+years ago.