One of Euthyphro's proposed definitions of to hosion says: '[T]he pious is what all the gods love...'. Scholarly analyses of Socrates' refutation of this definition have focused on its validity or even its 'truth'. By contrast, this paper restricts itself to the refutation's logical structure, particularly the way Socrates juxtaposes the agreed-upon premises to derive a double or 'chiastic' contradiction. In this article, I lay out the details of Socrates' ingenious logical construction, without regard to its validity or fallaciousness, and (...) argue that the chiastic contradiction alone makes possible Socrates' refutation of Euthyphro's claim to expertise in the realm of to hosion. (shrink)