How should a Stoic respond to political division and upsetting news?

The upsetting part of political news is never the event itself. It is the judgment you form about it. Epictetus states this as a general law of the mind: "Men are disturbed, not by things, but by the principles and notions which they form concerning things" (Handbook 5). A headline, a vote, a policy, an opponent's tweet: none of these things can enter your mind and disturb you directly. What disturbs you is the verdict you attach to it, the thought that this should not be happening, that these people are simply bad, that the world is falling apart.

This is easy to misread as a claim that political events do not matter, or that you should not care. That is not the argument. Epictetus is not telling you the news is fine. He is telling you where the disturbance actually comes from, so that you stop mistaking your own reaction for the world's fault. He sorts people into three stages on this point. The uninstructed person blames others for his bad condition. The person just starting philosophy blames himself. The one who is fully instructed blames neither others nor himself (Handbook 5). The goal is not self-blame in place of other-blame. It is seeing clearly enough that blame, of either kind, stops being the reflex.

Marcus Aurelius takes this directly into the territory of people you find infuriating. He opens Meditations 2 by telling himself what to expect from the day: he will meet the busy-body, the ungrateful, the arrogant, the deceitful, the envious, the unsocial (Meditations 2.1). This is not cynicism. It is preparation, the same way an athlete expects resistance before stepping onto the field. And his diagnosis of why people act this way is specific: it happens through their ignorance of what is good and evil (Meditations 2.1). Someone who has the wrong idea about what actually matters will act badly, predictably, the way someone with bad eyesight will misjudge distances. Marcus's response is not to write them off but to recognize that we are akin, made for cooperation like hands, feet, eyelids, the rows of upper and lower teeth. To turn away from them in anger is, on his view, to act against your own nature (Meditations 2.1).

Meditations 11.18 gives a longer sequence for the moment you actually feel provoked, worth having in mind when you open the news or a comment thread. Consider that people are made for one another. Consider what compulsions of opinion actually drive them. Consider that if they act rightly you have no complaint, and if they act wrongly, it is involuntary, from ignorance, since no soul willingly gives up the truth. Consider that you yourself do wrong often enough, and abstain from more faults out of cowardice or concern for reputation than out of real virtue. Consider that you rarely understand the full circumstances behind another person's act. Consider how brief a human life is. And last, the line that does the most work: it is not men's acts which disturb us, but our own opinions about those acts (Meditations 11.18). Take away the opinion that this is a catastrophe, that these people are simply enemies, and the anger goes with it.

None of this asks you to stop having political views or to stop acting on them. Voting, arguing a position, working for a cause: these are your own actions, and Epictetus places your own actions, your pursuits and aversions, squarely among the things in your control (Handbook 1). What is not in your control is how the vote goes, what other people believe, or what the news reports tomorrow. The discipline is to separate the two, so your energy goes into the action itself rather than into resentment at people who see it differently.

A concrete way to use this: before you open the news tomorrow, name in advance the kind of thing you expect to find there, the way Marcus names the busy-body and the ungrateful. Then ask, of whatever actually disturbs you, whether the disturbance is coming from the event or from your judgment about it. Usually it is the second. That does not make the event unimportant. It tells you where the actual work is.