↖ Homepage of the site 'What to do with your life?'
      

Why are all the theories formulated over the past 2000 years concerning living well together shaky?

Because they are based on simply plausible visions of humans, resulting from introspection.

Why hadn't we guessed historically the correct representation of what a human is? For example, in antiquity, the atom was divined, long before it was discovered via the modern scientific method. Certainly, at the same time, this theory which proved to be correct coexisted with others which were invalidated, but it still already existed.
The reason why this did not happen for the representation of humans is probably linked to the fact that cognitive dissonance, and more precisely its consequence which leads to lying to oneself in good conscience, is counter-intuitive. The philosopher Kant still believes that we choose to lie.

Go deeper

Refer to question 'What is a human?'