Not only do the Italians feed them, they sell bags of birdseed to tourists, who in turn feed the pigeons.
The Italians choose not to feed them, but sell all the feed to tourists.
mnli hypothesis: The Italians choose not to feed them, but sell all the feed to tourists. premise: Not only do the Italians feed them, they sell bags of birdseed to tourists, who in turn feed the pigeons.