How economic inequality harms societies

Richard Wilkinson TED lectures
http://www.youtube.com/watch?v=cZ7LzE3u7Bw

Rational decision making?
http://www.ted.com/talks/dan_ariely_asks_are_we_in_control_of_our_own_decisions.html

Irrational economics TED lecture
http://www.youtube.com/watch?v=UbfIWn_Rt1k

Externalities
http://www.youtube.com/watch?v=h68BQjMJNNA