Are humans rational? Sure, but they are also irrational. Are we driven by self interest? Yes, but we are also moved into other interest.
To pick a few extreme tendencies of human nature while ignoring their opposites -- opposites that are just as much a part of human nature -- as does modern economics, is wrong.
Modern life has made us split. Instead of whole people we are consumers, producers, 'economic agents' casting 'dollar votes', profit maximizers.
And then we behave largely, though not entirely, as modern economics describes us: not as people but as products.
But therein lies the beauty of God's gift to us -- that of free choice. We can never be completely conditioned! So how do we find our way out?
It is this watching of ourselves that allows us to see successively:
1. That our lives are unsatisfactory
2. That we are expressing a very limited number of extreme proclivities
3. That there is a system at work that shapes society
4. That it is possible to break out of the system
5. That we can live lives where we are no longer split but rather whole, expressing a beautiful range of tendencies lead by love.