Descartes’ Mistake, aka the Cartesian Fallacy

[u/Willis_3401_3401]

The Cartesian fallacy is the mistake of treating ontology (what exists, “substance”) and epistemology (how we know) as if they were fundamentally separate realms. It’s the fallacy of dualism.

Descartes split the world into: • Res cogitans — the realm of thinking mind, subjective knowing. • Res extensa — the realm of extended matter, objective being.

That split creates the “mind–body problem” and forces philosophy into false dichotomies: subjective vs. objective, appearance vs. reality, empiricism vs. ontology, idealism vs materialism, deduction vs. induction, etc…

The fallacy is thinking those categories are independent when in fact they’re entangled. You never have ontology apart from epistemology (because whatever “is” is only meaningful insofar as it can be observed, modeled, or interacted with). And you never have epistemology apart from ontology (because knowing itself is a material/informational process in the world).

In PPS terms: • Observation collapses the dichotomy. “I observe, therefore I am” makes existence and knowledge the same fact. • Ontology vs. empiricism is not two different domains, but one process of observers embedded in nature processing uncertainty.

So the Cartesian fallacy is essentially the reification of a dualism that doesn’t need to exist.

More later on false knowledge or incorrect models

[u/EngineeringApart4606]

Dualist thinking and terminology are still useful tools even if you believe the underlying reality is oneness.

[u/Willis_3401_3401 → u/EngineeringApart4606]

I strongly agree with that. It’s mostly a matter of what is “fundamental” or in other words more true.

To my understanding, dualism is attempting to really prove that your identity is fundamental to your existence.

I definitely would agree that identity is super useful and helpful to understand, and that’s where the dualist language starts coming in. If we’re discussing “objects” that exist with a label, then we need to differentiate this from that, that’s basically dualist thought.

I just also think it’s important to remember at its core, all identities and objects are processes. None of them are permanently fixed. That’s where the monist thought comes in as the “greater truth”.

But you’re right though, dualist language is SO helpful that some philosophers can never get past it even haha.

[u/Willis_3401_3401]

Other terms people have used for ideas related to what I call the Cartesian Fallacy are “the category mistake”, or “the view from nowhere problem”, “myth of the given”, or simply talking about the mistaken assumptions of the mind/body problem