Perfect logician

It doesnt really say that you need to decide wether the boy is given back or eaten so there is a lot of possibilities of his fate. The guess that she should say you will eat my kid is a paradox alone. If you say you will give him back it is a risk. Though you can say, "You will eat my kid if I answer incorrectly," and vice versa, "You will give him back if I answer correctly," just say them both and you are set.