Descartes assumed an ego where only raw thoughts existed as data.

Evidence

‘I think’ is his ultimate premiss. Here the word ‘I’ is really illegitimate; he ought to state his ultimate premiss in the form ‘there are thoughts’. The word ‘I’ is grammatically convenient, but does not describe a datum. When he goes on to say ‘I am a thing which thinks’, he is already using uncritically the apparatus of categories handed down by scholasticism. He nowhere proves that thoughts need a thinker, nor is there reason to believe this except in a grammatical sense. — Bertrand Russell, History of Western Philosophy, 2082

Categorization

• DEFINE: DEFINE clarifies the logical flaw in assuming a thinker behind every thought.
• corroborated: 2 independent passages support this claim — Bertrand Russell, History of Western Philosophy, 2082
• XREF: connects to: Descartes grounded certainty in thought, establishing mind as primary over matter. — Bertrand Russell, History of Western Philosophy, 2069