On The Daily Show for 10 October 2015, Roy Wood Jr. asked some White folks what they made of the Million Man March Commemoration slogan "Justice or Else," specifically what was meant by the "or Else." Wood got answers indicating "it sounds threatening" with more specifics from one young woman including, "like riots, like violence, shit [bleeped out] going down" and several more phrases indicating bad things like "blood, gore, death." Wood responded "You get all that from 'or Else'?!" The young woman answered back "It's a wide-open category, open for interpretation" — and Wood got the great laugh line I hear as "No wonder White folks write all the horror movies; [you?] just conjure up crazy shit in your heads."
Wood's next line — a transition back to the Million Man March — was, "So I guess a slogan demanding fairness and equality can easily be interpreted by certain people as murder and mayhem"; and he returned to the march and got the specific answer, to "or Else" in this context: a nicely anticlimactic one, that the "or Else" planned was holiday economic boycotts.
As one with some experience in the propaganda and protest biz, and a one-time teacher of courses with the word "Rhetoric" in the title, I'll get pedantic enough to say the young White woman was exactly right on "or Else": "Its a wide-open category, open for interpretation," which is what makes it effective.
It's like the phrase "by any means necessary," or like a US President saying "No options are off the table." To use an example out of Orwell's Nineteen Eighty-Four and recent history: Does "by any means necessary" include throwing "sulphuric acid in a child's face" if that is thought necessary in the struggle (whatever struggle)? Was the President of the United States threatening to bomb Teheran off the face of the Earth? Probably not, but strategic bombing is an option: obviously; with a couple of bombs the US blew most of Hiroshima and Nagasaki off the face of the Earth, and we and the British did a pretty thorough job more conventionally destroying Dresden.
Similarly, in a sense, with demonstrations.
During the National Student Strike of 1970, my group at the University of Illinois did a good job of keeping things peaceful (even if we didn't do well getting media coverage: "No blood, no news," as one newsroom exec told us explicitly). Still, we were aware that we had a limited window of opportunity to negotiate with the U of I administration: "As long as they look at a delegation of us and see a mob at our backs," however peaceful, or small, the actual crowd, we had leverage to deal.
Demonstrations are a way of exerting power in Hannah Arendt's sense in On Violence: large numbers of people gathering together in concerted action. From the point of view of The Powers that Be, however — always and inevitably — large demonstrations carry an implicit threat: the crowd may get violent, and its very existence is at least somewhat disruptive.
And that is fine. "Power concedes nothing without a demand," as Frederick Douglass said, and at least on occasion the demand must be backed up, minimally by the threat of disruption.
Which returns us to perceived threats.
In the US everything political, to overstate a bit, is at least "inflected" by race, and the racial (or racialist or racist) aspect with the White understanding of "or Else" is a generalized White fear of Blacks on the solid as well as pathological grounds that we Whites as a group have ripped off, exploited, and otherwise injured American Blacks as a group, and those Blacks might well want restitution ... and some might want revenge.
So let us cut the crap: "or Else" is always an open-ended threat made more effective in this instance because US Whites generally see Blacks as a threat to start with and because the Powers that Be see any massing of the masses as a potential danger. If the "or Else" is merely "a slogan demanding fairness and equality" with the threat no more than an economic boycott — well that is something for which Whites should be grateful, but also something demonstration organizers shouldn't repeat too often.
Open-ended threats open to nervous if not paranoid interpretation — can work nicely.