Full Idea
Locke says the doctrine of innate ideas is either reduced to triviality (that we have the potential to acquire knowledge and concepts, which makes all ideas innate), or to the absurd thesis that new-born children know logic, maths and metaphysics.
Gist of Idea
Innate ideas are trivial (if they are just potentials) or absurd (if they claim infants know a lot)
Source
report of John Locke (Essay Conc Human Understanding (2nd Ed) [1694], 1) by Nicholas Jolley - Leibniz Ch.4
Book Reference
Jolley,Nicholas: 'Leibniz' [Routledge 2005], p.113
A Reaction
A very effective attack. The defence would have to be the claim that there is no way for certain ideas to have entered the mind (because they are too basic, or too abstract, or too huge), so they could only arise from within the mind.