In A Modest Proposal, what is Swift's main point? What is the speaker's main point? How the speaker uses persuasion? How does Swift use irony?

A Modest Proposal is one of the wittiest and well-written satirical texts ever. In this text, the speaker is arguing that Ireland's impoverished citizens can better themselves financially by selling their young children to the rich for food. The speaker persuades the reader by concretely organizing his argument (ie: firstly, secondly....sixthly), stressing the benefits to all involved (tavern industry, the poor, the rich, the government), and using favorable statistics to back his argument (cost of raising a child vs. selling one as food for profit. For example:

Thirdly, Whereas the maintainance of an hundred thousand children, from two years old, and upwards, cannot be computed at less than ten shillings a piece per annum, the nation's stock will be thereby encreased fifty thousand pounds per annum, besides the profit of a new dish, introduced to the tables of all gentlemen of fortune in the kingdom, who have any refinement in taste. And the money will circulate among our selves, the goods being entirely of our own growth and manufacture.
Fourthly, The constant breeders, besides the gain of eight shillings sterling per annum by the sale of their children, will be rid of the charge of maintaining them after the first year.

Swift's aims are two-fold. First, he wants to mock government officials' and politicians' rhetorical discourse. Swift is suggesting that politicians often lose sight of the actual people involved in the issues they are discussing, so the solutions they put forward are widely impractical (such as his proposal is). Secondly, Swift is able to put forward his own actual argument, but having his speaker seemingly refute it:

Therefore let no man talk to me of other expedients: Of taxing our absentees at five shillings a pound: Of using neither cloaths, nor houshold furniture, except what is of our own growth and manufacture: Of utterly rejecting the materials and instruments that promote foreign luxury: Of curing the expensiveness of pride, vanity, idleness, and gaming in our women: Of introducing a vein of parsimony, prudence and temperance: Of learning to love our country, wherein we differ even from Laplanders, and the inhabitants of Topinamboo: Of quitting our animosities and factions, nor acting any longer like the Jews, who were murdering one another at the very moment their city was taken: Of being a little cautious not to sell our country and consciences for nothing: Of teaching landlords to have at least one degree of mercy towards their tenants. Lastly, of putting a spirit of honesty, industry, and skill into our shop-keepers, who, if a resolution could now be taken to buy only our native goods, would immediately unite to cheat and exact upon us in the price, the measure, and the goodness, nor could ever yet be brought to make one fair proposal of just dealing, though often and earnestly invited to it.