Cartesian Dualism is both wholly responsible for the worldview you probably hold now and probably the most disappointing thing to have happened to anybody ever in the last couple of hundred of years.
Here’s the deal. Dualism as defined by Descartes (hence Cartesian, our “C” this week) has two components:
1. The world is divided into two separate, distinct, dual realities (in an ontological sense; we’ll get to “O” eventually).
2. One of those “halves” is better than the other. This is where Descartes borrowed from Plato… reality must be ranked in a top-down hierarchy rather than represented in terms of an equal-but-different distinction.
This has been the case since Plato and the dawn of Christianity so it’s not like Descartes or modern feminists or me invented it; it’s super ingrained in the Western world and, quite simply, that’s that.
Here’s some dualist hierarchies (again–that means there are two groups and one is better than another) that you as an American and/or Western European probably at least to some degree assume, implicitly or explicitly:
[Note: I am NOT supporting these dualities as reality or even suggesting that they aren't super offensive, just saying they are wedded to the Western worldview so you are at the very least familiar with them]
Men are superior to women
Whites are superior to non-whites
Technology is better than nature
Wealthy people are better than non-wealthy people
Straight people are better than gay people
You get the picture. Cartesian dualism is maybe okay as a metaphysic (see “M” in like a dozen days) but for now let’s agree that it’s responsible for lots of people being shitty to lots of other people.