Staccato is simply an articulation, and one not unique to the piano, therefore it's definition is more fundamental than anything pianistic. Well Rainer at least you admit they won't sound staccato because the instrument can't make staccato there.
Indeed I do admit that, and I never intended to imply otherwise. As you rightly say it is an articulation, but there are nevertheless two aspects to it. One is the effect you get (or hope to get, i.e. shortened notes), the other is what you do to (try to) make that effect happen (though it may be a slightly oversimplified way of putting it, basically you "jab" at the notes, and this has the side-effect of making them louder).
The point I have been trying to get across is that generally on the piano you would tend to give a staccato note the same overall weight of volume
(a term I would loosely define as the product of volume and duration (not a simple linear product, though, but one which takes into account the note's decay envelope)) as you would give a non-staccato note in the same context. Since a staccato note's duration is shorter, its volume needs to be increased in order to keep its weight the same. This is an important side-effect of trying to play staccato on the piano. Since in the present context the absence of dampers makes the primary
effect (reduced duration) impossible to achieve, I suggest the composer may (or must) be aiming for the side-effect instead
. By instructing you to try to play
staccato, he expects you to "jab" at the notes as you would if you were playing in an octave with dampers.
The passage is directed to be played ppp, which I may add is difficult to accomplish and actually causes the pianist to be on the verge of dropping notes meant to be played.
Aha! This is most interesting, and I believe it favours my proposed solution to the mystery. By inviting you to "jab at" the notes, the risk of such unintentional drop-outs is reduced.
Perhaps more simply and straight forward (lex parsimoniae), Ginastera just didn't understand the limits of the piano and I have been giving him too much credit.
Hmm, I'm not sure about that. It may be simpler to dismiss the composer as ignorant than to try to understand what he had in mind, but it's not an approach I would take lightly. Every self-respecting composer should be aware of the limitations of all the instruments he writes for, and from the guy's biography it seems he was also an eminent teacher
of composition, so I suspect you would be unjustly disrespecting him.