If there is one thing many political ideologies have in common, it is that they attempt to end what they perceive to be oppression. And leaving aside very unorthodox definitions (like say religious fundamentalists’ “oppression” of liberal choice), it seems very clear that these ideologies, whether liberalism, socialism, ecologism, anarchism etc. have a common understanding for what oppression is. Indeed, one could say that it is a matter of degree for how much oppression should be eliminated, with ideologies like anarcho-primitivism and ecologism at the far end since they oppose any kind of oppression of animals and nature.
The question then is why has no one attempted to unify these oppressions into a common theory, in order to address them head on? In physics for instance, there are attempts at a theory of everything in order to understand the universe. This seems especially important for oppression given that to end it in all of its forms it is important to understand its various causes and functions.
The immediate rebuttal is “oppression” is just a word, and can describe any number of things which have nothing to do with each other. This is, of course, true in a sense. As Simone de Beauvoir pointed out for patriarchy, many forms of oppression seem to predate things like the state or capitalism and can act independently of it. Thus a lot of political factionalism, or even complete differences in ideology, can be explained as an attempt to address different issues.
But this is not to say that there has been no progress in this issue. One technique to address multiple, overlapping oppressions has been intersectionality. Indeed, if this was just a vague descriptor then even this theory would not be viable. Of course oppressions vary extremely as do their causes and functions, but it is still worth trying to attempt to solve it as a single problem. As movements like Occupy Wall Street showed, there has been too much of an emphasis prior to the economic crisis on single-issues which often coincide and feed off one another. Without a proper understanding of oppression, activists will be trapped in an endless game of whack-a-mole where one form of oppression is restrained but another, inter-related one regenerates in its place.