There are many economic theories, but I don't know any that asserts that in such a general way.
There are many economic theories, but I don't know any that asserts that in such a general way.
Adam Smith argued that landlords (those living off land rents) had interests aligned with the common good, as did wage laborers, but that capitalists in general had interests divergent from and often opposed to the common good of society. (See, An Inquiry into the Nature and Causes of The Wealth of Nations, Book I, Chapter 11.)
Or because nobody actually believes it. Even the more staunch laissez-faire defender believes some self-beneficial acts to be contrary to the common welfare, like stealing or getting reelected after promoting anti-market policies.
Likewise, anti-capitalists argue that many self-beneficial actions are also beneficial to society, like demanding to be paid fair wage or even taking control of their means of production. "Workers, unite!" is not a call for self-sacrifice.
People cherry-pick the bits and pieces that make their actions look good and ignore the rest.
Sure, but that's not an economic theory.
But when you look at the real world rational actors is often not much more than an euphemism for greedy actors. Exceptions not withstanding. While real-world capitalism without doubt enabled an enormous gain of total wealth that is hard to imagine in more fair - or whatever you want to call it - economic systems I see no way that you could argue that it was the best option at least for the last couple of decades or that we should or even could go on in the same way.
An example: http://www.amazon.com/The-Great-Deformation-Corruption-Capit...
What you won't find is agreement over what exactly is wrong with the current system, what exactly causes those problems, and what to do about setting to solve them.