My solution makes the most sense, so that must mean it's the best
"twenty thousand may be reserved for breed"
There were a lot of poor women in Ireland who were forced to spend all of their time begging for food to provide for their children who were "all in rags". This use of pathos by Swift was used to make it look like he felt bad for the how the children were living.
Swift says " as to my own part, having turned my thoughts for many years upon this important subject" using ethos to explain that others have tried, but his solution makes the most sense.
Swift uses terminology meant to describe animals to describe people. He uses logos to describe how many children there are and how many "breeders" were available by saying "twenty thousand may be reserved for breed". He also describes how children could be prepared for consumption.
Call to Action
I am open to other opinions, but they must meet a certain criteria
This is when the satire is unmasked. Swift
By saying "after all, I am not so violently bent upon my own opinion as to reject any offer proposed by wise men", Swift is claiming he is open to other opinions on the subject, but it must meet certain criteria.