What is the real thesis for A Modest Proposal?

What your answer is is more like the theme of the essay. The thesis would be what Swift actually proposes. His thesis starts in the title:

A Modest Proposal: For Preventing the Children of Poor People in Ireland from Being a Burden to Their Parents or Country, and for Making Them Beneficial to the Publick.

Swift's thesis is that if the poor simply ate their babies, the above would be accomplished.