> talking of IQ in a quantitative way ("x points less")
I read that as a within a single individual, case A (no brain damage from cause C) vs case B (with brain damage from cause C), where using it as a shorthand for intelligence differences within a single individual makes it a useful shorthand for most readers, IMO.
I read that as a within a single individual, case A (no brain damage from cause C) vs case B (with brain damage from cause C), where using it as a shorthand for intelligence differences within a single individual makes it a useful shorthand for most readers, IMO.