Tabula Rasa was a legitimate Psychology theory in the mid 1900s for a handful of years. A lot of wild and downright evil experiments were done to try and prove it, and they consistently came up empty. So it was thrown away as a scientific approach to how humans work and think.

But the Left literally builds its foundation on the notion of it, its why they say things like "teach men to not rape," even though they don't use the actual term anymore due to its negative connotation.