Public demonstrations take many shapes, but the general, modern template of a peaceful protest that has emerged over the past several hundred years involves getting a group of people together in a public place in order to make a statement about something of possible public interest.
This might mean picketing a business that’s mistreating its workers (from the workers’ perspective, at least) in order to encourage that business to change how it operates by airing their concerns, or it might mean rallying, marching, or orchestrating some kind of public display meant to attract attention and garner press for a particular ideology, cause, complaint, or political party/candidate.
Demonstrations can be for something or against something, and they can be focused on an immediate outcome or a longer-term sort of play.
Some demonstrations grab attention and headlines by being disruptive, not just public: demonstrators may throw cans of soup at famous artworks in museums (which are protected by glass and thus, unharmed) to protest climate change, or they might host a sit-in at a diner where they know they won’t be served, occupying as many seats as possible in order to protest discriminatory laws and promote civil rights.
Evidence is mixed as to the effectiveness of different sorts of protest action in different contexts, but there does seem to be some support for the idea that the existence of a “radical flank” of a given movement (one that dramatically disrupts things and maybe even annoys people on a regular basis) can lead to more support for the moderate, less-radical version of the argument and the protestors who voice it.
There’s also evidence that combining shorter-term strategies with longer-term reform efforts can be more effective than either reform or protest, in isolation.
There’s also a large body of evidence (for this field of study, at least) that suggests nonviolent tactics are almost always way more effective than violent ones, and that a large number of participants in protest activities will almost always lead to more positive outcomes (from the perspective of those doing the protesting) than enthusiastic demonstrations by small groups of people.
It also seems that protests benefit from having aligned (or relatively aligned) people in power—politicians and other decision-makers (“elite allies”) who largely agree with the protestors—and that having cohesion within the protesting population (everyone asking for the same thing and voicing similar complaints) will tend to help their cause, as well.
These data points are imperfect and won’t apply in all contexts, and there are exceptions that fly in the face of (for instance) the norm of nonviolent demonstrations tending to do better than violent ones.
That said, the data we do have gestures at why those who oppose a given group of protestors often try to paint them as a small group of violent radicals, and often try to position them as being outside the mainstream. If they can successfully label demonstrators in this way, they stand a better chance of disempowering them and stripping away their legitimacy in the eyes of the public, and in the eyes of elites that might otherwise support them.
There’s also reason to believe that the “radical flank” approach can backfire, all unto itself, as extreme tactics can lead to annoyance and even hatred toward those engaging in those tactics, and if those radicals are generally perceived to be undifferentiated from their non-radical fellow travelers, that can further delegitimize everyone involved and the causes for which they’re fighting.
Interestingly, while some studies show the majority of people in some countries believe that protests seldom make a difference, they actual sometimes do—though usually not in the way protestors think (or seem to think) they will.
On occasion, a protest will result in relatively rapid changes in how things operate (government concessions to workers from a particular industry, for example), but usually the most significant impact demonstrators can hope for is an increase in awareness of the issue in question, alongside a small, slow change in the level of support the protestors’ stance on that issue enjoys.
Over time, then, protests and associated actions (like reform efforts within a governmental or economic system—people running for office and voting, alongside lawsuits and other legal actions) can result in huge, sweeping change, but even though folks on the ground might desire and demand that change happen immediately, in many cases that’s not in the cards: sometimes because those in power don’t have the ability to (for instance) “end racism” or “stop immigration,” and in some cases because the issues being protested are systemic, not the result of someone’s executive deciscion (poverty, for instance).
There are opportunities to make more targeted appeals that might be short-term actionable (like demanding shelter for the homeless in a particular city, rather than demanding an end to the poverty that makes some people homeless), but for some causes and in some contexts, playing a long-term game (aiming for awareness and mobilization over the course of decades, if necessary) with a sequence of short-term, concrete milestones along the way toward a more substantial outcome, seems to be the most consistently successful approach (historically, at least) to collective action.