Probably right around the time Newt did his 'Contract with America'. Basically saying the gop would never work with the Dems - it's been game on ever since. This attitude unlike money HAS trickled down to all walks of life.
Everyone wants to be special and it is socailly acceptable to bash, trash and pussy grab any group one happens to disagree with.
Hope I'm not being too cynical. It is not the way I live my life. Not having a TV helps but the internet has plenty of it.

Society is becoming increasingly polarized. Personally I think this is because more and more people confuse their beliefs with their identity. As a consequence, they can't tolerate those beliefs being questioned, however gently; in some cases they can't handle simple passive not buying into it or being Not Part Of My Group. In that environment simple difference becomes an existential threat.

We see it consistently with authoritatrian / fundamentalist believers and how they treat unbelievers and even fellow Christians of other sects all the time. But sometimes, you see it in the disagreements between other groups -- men and women, political liberals and conservatives to be sure, sometimes even from surprising places. For example I had someone rip me a new one a couple of days ago right here on agnostic.com because -- well, frankly, I'm not sure why. Words were written down, assertions were made, but I was in the rare position that none of it made any sense to me and a lot of what was taken umbrage to was in "can't you take yes for an answer?" territory. In that case I think I just encountered a borderline personality disorder situation and unwittingly pressed some button or other. Who knows. I patted him on the head and let him have the last word; that seemed to be what he wanted.

This has always been true in human discourse (especially on the Internet!) but it does subjectively seem to be getting worse and anecdotally, I seem to be encountering it more often online and it seems to be getting more personal. The above-mentioned person cast aspersions upon my intelligence and my parentage for example, and just today I was castigated by a couple of women who have been very nice to me in previous discussions and now are assuming way too much about my personal beliefs and motivations and doubtless lowering their estimation of me as a human being because we've engaged on a different topic than we usually do, one on which we have less agreement apparently.

But guess what ... on the Internet you need thick skin and I have it. I am not under the illusion that I'm going to be liked here by one and all at all times. Heck, I no longer even have meaningful expectations of how I'll be treated at any given moment by my family anymore, much less total strangers.

But still, it does seem less civil in the past couple of years. Dare I lay that on Trumpism? Not sure if it's a cause or a symptom. Probably both. It certainly can be depressing at times.

The world is becoming more radical I'm afraid. It is my belief that most people fall somewhere in the middle.