Any suggestions on ways to deal with a senior who constantly instigates fights about general topics like politics or current events?

Can’t argue without an audience. Give it no audience whatsoever. The minute it starts, leave, no exceptions

We are so divided in our country now that I just can't be around it to tell the truth. I leave.
In my own household my partner is soooo much more into the daily political drivel that is soooo repetitive. That just goes on and on and on and on. And is so predictable. I don't want it and I try to enforce not speaking over much about the same old story. I garden. I read. I walk. I cook.
I am 78. I have my one vote and cast it the best I can.
If you notice, with all the talk talk talk, no one's mind is really changed. Not a vote is changed but that it doesn't come from within.
I just make certain, and it's easy in these times when we can't meet up anyway, that I have an escape route, and I make "The Great Escape" whenever necessary to my own mental well-being.

Have you ever tried agreeing with him and moving on to another subject?

My dad doesn't even watch the news, but let someone tell him anything and off he goes. I will just acknowledge what he is saying with an "oh yeah, that is one way to look at it." Then we are off to the next rodeo.

Once you realize that you will never win, you can start looking for ways that shut him down without the drama of an argument. Because it takes two to argue, if no one engages he doesn't have an opponent.

I don't like advocating this, but I suggest you get right in your parent's face and lay down the law. The important thing is to remember that your parent is not arguing to make a point, but rather to command attention.

I was not raised in a family that argues, so when I married my husband, my FIL was a new experience to me. He, too, loved to start trouble with endless political topics, but he considered his pontificating to be "discussions." One-way discussions, but discussions nonetheless. With a family of seven kids, seven in-laws, and 18 grandchildren, he was in his element holding court at every family event (and there were multiple such family events every year).

I was always respectful but largely ignored him when he'd try to bait me, but he finally went over the line when he started in on my youngest son. He was berating him, talking over him, and ignoring the excellent argument my son was giving in opposition to his. I guess I forgot my "respect your elders" training, and I'd had enough. I got right in his face and just said very quietly, "LAY. OFF. MY. KID."

Amazingly, he never pulled that stuff again with anyone in my family. I'd drawn the line in the sand, and he got a clear message of what I'd put up with and what I wouldn't. No one had ever done that to him.

It's really sad that he never saw the damage he did, because when he died three years ago, his grandchildren weren't too upset by it. They don't have fond memories of their grandfather, and as he passed on his annoying habits to a couple of his sons, his legacy of being obnoxious continues, albeit to a lesser degree. Still, my daughter refuses to go to any family events, and I can't say I blame her.

Few people continue to argue with the wall (though some do so). Who are you trying to convince when you argue back? Because you won't convince THEM. Simply say "That is an interesting point of view; can you repeat it for me". When they do just say "I am going to give that some serious thought". or "I hadn't considered that". Or "I so appreciate your point of view". You know. Pretend you are a Psychologist and give them nothing.
It works. As hard as it is in the beginning, and as many times as you will leave with the tongue bleeding from having been clamped down on, it gets easier and easier and easier, and ultimately it becomes FUN! If a sort of sadism.
There is absolutely nothing so frustrating as someone who will not argue with you, right?

Set boundaries.

If I had met my ex husband’s extended family ahead of time I would never have married him.

My line in the sand was a year or two after we married. There was a big family birthday party in a local Asian restaurant. 25 or more people, ranging from 90+ to my son who was 6. Uncle Jim started in on the racist jokes. I could not believe it.

I stood up and told him my son was not going to be exposed to the garbage coming out of his mouth and he should be ashamed to be talking like that in front of his granddaughters too. I would not spend another moment listening to him.

I gathered up my son and went to leave the restaurant. You could have heard a pin drop. The family were shocked, nobody had ever spoken back to Uncle Jim as he was known for his temper. They were even more shocked when he apologized to me and my son and promised to mind his language. He never spoke that way again in front of me.

For OP’s situation, you are allowing one person to dictate your socializing. I would very clearly state that he is not welcome to join in when you have friends over. If he does, then new living arrangements must be found within the month.

Also if you are paying the cable bill, electric bill, etc., you have every right to decide what is watched on TV’s in the public areas of your house. Me, I would block Fox News or whatever station he is watching.

My Dad does not live with me. He watches various crazy podcasts that are full of conspiracy theories. If I call into question the crap he is saying, his standard response is that I am mentally challenged and have no right to challenge him. But he is a retired teacher who hates to have his authority questioned, especially by a woman.

Grey rock is the best answer, the more you do it the easier it is.

OMG, I can relate to your dilemma. My 97 year old father lives with us and watches Fox News 24/7 in our family room - even though he has his own tv in his bedroom. I finally “had it out” with him yesterday and said “Don’t you get tired of watching the same thing all day? I am tired of listening to it. Do you want me to write a list of channels that might have other shows to interest you?”. We “got into it” and he accused me of trying to control him and what he watched. My reply was “No, I’m just tired of hearing the tv all day/ same old stuff”. He went into a pout and turned the tv off. He acts like a child and is now being a martyr sitting in the chair hunched over with his eyes closed. I’m not taking the bait - it’s so peaceful and quiet before he gets up in the morning and after he goes to bed at night. We, too, have stopped socializing because he interjects and takes over the conversation with his political opinions. I agree with Midkid58 - you just have to confront him; the negativity will take over your soul.

Ugh.

You've just described my 68 yo DH.

While WFH he has had the TV on to FoxNews 24/7 and has gotten so incredibly amped up about EVERYTHING...he's really hard to live with, and being 80% deaf and refusing to wear his HA's, he's very loud and comes across like an old fart.

Last week he was trying to engage our daughter in some debate and he will not bend to listen to anyone else's POV. He is RIGHT and that's that. She simply ignored him. That made him so mad.

I did tell him, and have been telling him, that WE (both of us) are completely IRRELEVANT at this stage of our lives. Nobody wants to hear what we have to say nor care what we think. (I told him that as a white woman, I have NEVER been 'relevant' and our kids have always thought my ideas and ideals are stupid)

He will go down swinging, I swear. I tell my kids if he gets out of control, they should simply, quietly pack their kids and leave. And they do.

If I had a dollar for every time somebody asks me what's 'wrong' with my DH, I'd have a bundle. I know the deafness and the endless loop of right wing blather has made him much worse.

What's wrong is that he only sees one side of anything and nothing anyone says or does is even allowed into his brain.

You're not going to change your parents. Don't argue with them. My DH LOVES a good argument, but he also loves making other people look/feel stupid.

In our case, before I can let him retire, he HAS to get some counseling. So much anger---and though I try to divert his attention, he is a real pill. During COVID I have taken many long, endless drives and have kind of self isolated in the basement. I may go a whole day and not speak to him at all.

I just got put on a new med as my heart is acting up---tachycardia--brought on by, you guessed it STRESS. And I KNOW DH is the major source of that.

Be absolutely straightforward with your dad and mom. They wander into political arenas or any other area you aren't comfortable with and let them know that is not appropriate and tell them you won't put up with it. My kids have done this and it has helped a little, tiny bit.

Some family members like to talk politics and some get all up in the air at times. I try to change the subject, but a few minutes later back to arguing from one of them. Told over and over we do not want to discuss politics. Ends up in a heated conversation. Now it is better because we ignore them and do not add fuel to the fire. Visiting is much nicer and peaceful.