A Modest Proposal is told in the first person point of view from an unnamed narrator. The Proposer never gives away his identity, because he's more interested in solving all of Ireland's woes. We can't really trust his agenda (because he wants to eat kids, no biggie), and we can definitely see his personal biases creep in. On the plus side, he has some good recipe ideas. Check out our "Character Analyses" to read up on Swift's multiple identities.
Here's the tricky part: Jonathan Swift's perspective is definitely mixed in with his fictional narrator's. Of course, you can argue that an author always leaves a bit of their own personality in the characters they create. But in this case, Swift is employing a form—the political essay—that he frequently took pretty seriously in order to produce a wicked satire. Try this on for size:
I can think of no one objection that will possibly be raised against this proposal, unless it should be urged that the number of people will be thereby much lessened in the kingdom. Therefore let no man talk to me of other expedients. (28)
In early editions of A Modest Proposal, the expedients (or suggestions) that Swift mentions were italicized to show that he was actually serious (source).