Locke defines abstraction as such.
“The particular ideas received from particular objects become general, which is done by considering them separate from all other existences, and circumstances of real existence, as time, place, or any other concomitant ideas” P.293.
This is a sloppy definition and suffers from an ambiguity. I do not think that Locke meant the bolded “and” to be a logical and but rather he meant to use it to introduce a rewording of what came before it. If we broke down the sentence into its logical structure we see three sentences ‘considering them separate from all other existences’ which I will denote with a P, ‘considering them separate from all other circumstances of real existence’, Q, and ‘considering them separate from any other concomitant ideas’, R. That is to say (P ∧ (Q ∨ R)). Now P is very similar to R. To say ‘any other concomitant ideas’ means all other ideas with related existences, and wether or not you are considering an idea apart from all other existences or all related existances does not matter as you are still considering the idea completely alone. So now we can see that P and R are not just similar but are exactly the same. Then this means that Locke is saying is (P ∧ (Q ∨ P)). But this is going to be true regardless the truth of Q. It is just P and everything else after the ‘and’ is pointless. I can see no reason as to why Locke would include this unless he thought he was just reclaiming the previous statement. This creates a problem because P is not equal to Q. Locke has defined abstract ideas in two distinct ways. One is saying that abstract ideas are ideas considered separate from all other ideas and the other that abstract ideas are ideas considered separate from all other circumstances of real existence. These look very similar but the former, as Berkeley argues leads absurdities while the other is perfectly sound.
Look good?
edit: I have to take the bolded 'all's out for my argument to work. Can I do that.
edit2: that's a shitty argument for a number of reasons. I suck. Fuck Locke. :'( :'( :'(