There isnt a you, practically, there is infact an Us, and as an organism, the rule of large numbers wins everytime, we select for what we think is right as a social collective/organism.
That kind of thinking is accepted in science, but not wide spread amongst the singular individuals.
Older cultures didnt need to check for anything, decisions probably evolved through intra generational symbolism and stories about ghosts and evil spirits. Life wont answer the why, it just is, and if we push itll just eat us.
In the same breadth, science is nature too. So whatever works, really.