We. The Revolution

Before every negotiation/speech, you get a chance to try out one argument per statement and see their response (to select arguments on controller, press / to select the right side menu first. Press / to select the emotion menu again if you want to reveal an emotion after). Bad arguments have red highlight, good arguments have green highlight, and the worst/best have very pronounced highlights respectively. For this achievement, you want to choose all arguments with the heavy green highlights. From what I can tell, every emotion automatically has two arguments they work with and two arguments they work against, but the best/worst argument of the two will differentiate depending on the specific topic so you have to try to use context to figure out what the best arguments are per negotiation. I recommend doing this in most of the early negotiations that only have 3 arguments that need to be made, as some of the later ones have 4, 5, or maybe more arguments that you have to make. The achievement says negotiations, but I believe it also works on speeches (not 100% confident on that). I'm still figuring out the emotion/argument correlation, and I will update if I have a chart I'm confident on, but I will say that manipulate seems to work for 90% of cases for me.

Edit: I came across this chart recently. It appears to be accurate from what I've tested so far - https://steamcommunity.com/sharedfiles/filedetails/?id=22524...