socialism - from Marxs definition was a step toward communism..
(the ideal of communism was when the state 'withered away')

however socialism has come to mean something else, generally
social programs for people - national health plan, pension plan etc..

Capitalism - as it is right now, however leaves out one major component.
that of the external costs, the environment, the commons, nature if you will. And unless a system accounts for third party external costs, then the destruction of the commons will continue..

Ie. dumping pollutants in the atmosphere, or oceans/lakes, overfishing,deforestation. etc.
and its not just a matter of assigning costs..

see Amory Lovins, Natural Capitalism as a proposal