Costly Signals

As I grow older, I pay less attention to what men say. I just watch what they do.
Andrew Carnegie

Someone mentioned the concept of «costly signals», IIRC from biology regarding, e.g., peacock feathers or huge horns/antlers.

I think something similar can be said when it comes to judging others. How well can you trust their positions to be a honest reflection of what they actually believe?

It doesn’t mean that they aren’t trustworthy, but you can gather little evidence if what they say (usually) has positive to neutral consequences. A bit more if they actually showing some behavior (more effortful than just saying something). If what they say (usually) has negative consequences, I think you can trust them more to be honest. And the most if they are doing something that (usually) leads to negative consequences.

Of course, if you still want to have something to do with them if what they do is usually regarded negatively is another matter. But then, the majority is often wrong.