sobomobo

Yeah! I more meant that you don't need to use the phrase "I want to get a PhD in Political Science because of X," but instead can just explain how a particular program will help you achieve your career and research goals.

Regarding style, I don't think you need to necessarily defend why you want to get a PhD. As others have said, almost all SOPs begin with description of research interests, then move to qualifications (i.e. why you feel prepared to do this research), and then explain why this particular program is a good fit (name a couple faculty members you'd like to work with, various research institutes on campus, etc.). You can put in a sentence or two at the end about how this particular program will help you achieve your career goals (usually that you want to conduct research and teach at a university). Here's a really useful compendium of application advice from various people in the field: https://people.fas.harvard.edu/~jkertzer/prospective.html If you're on academic twitter, profs often retweet useful advice about applications, dissertation writing, the job market, etc. so that's another great resource (also a huge time suck haha)

Just got Berkeley reject

I highly doubt that the position itself would be an issue, but if your writing sample is overly polemical it may hurt you by raising other red flags for committees. A lot of programs get applicants who really should be applying to policy or law schools and don't know what a PhD program is all about, so if you submit something written in a measured, academic tone it sends a stronger signal that you know what you're getting into. Secondly, if it the paper comes off as abrasive, it may raise questions about what kind of person you are. That might be an unfair assumption to make, but departments are generally quite small and committees are looking for people who will be able to get along with others. Admissions decisions sometimes seem really random because there are so many qualified applicants, but even if they don't like the tone of your paper I'm sure if the rest of your application is strong you will be fine!