'm not sure how 'some' comes into play.
but 'there exists' is like an infinite OR connective
and 'for all' is like an infinite AND connective.
since both AND and OR can connect truth-valued terms to make a new term,
it is reasonable to allow 'there exists' and 'for all' to do so as well.

'some' as a connective doesn't make sense to me, as there is no way 
to talk about the truth value of a term made up using 'some'.
Unless you increase your truth-universe to include a bigger range of
values, and as an exer