15 The function of the infinitive phrase: To recover from a tragedy takes time.
Object
Adverb
Adjective
Subject

I think the correct answer is object.

paine is arguying that they had tried everything before coming to the conclusion that they needed to fight for their freedom.

argument: "every quiet method for peace hath been ineffectual."

claim 1: "our prayers have been rejected with disdain; and only tended to convince us, that nothing flatters vanity, or confirms obstinacy in kings more than repeated petitioning and nothing hath contributed more than that very measure to make the kings of europe absolute."

claim 2: "wherefore, since nothing but blows will do, for god’s sake, let us come to a final separation, and not leave the next generation to be cutting throats, under the violated unmeaning names of parent and child."