In the process of trying to grow its message from a hashtag spawned by three activists into a national political movement, Black Lives Matter—a decentralized organization with official and unofficial Facebook pages, meet-ups, and blogs throughout America and the world—is splintering internally on how to express that message, and even defining what that message truly is.

After all, when an article says Black Lives Matter interrupted a campaign event, who is a part of Black Lives Matter, anyway? The answer to that question is even harder to answer.

The answer to that question might be a small group of people who self-identify as a “radical organization.” The answer to that question might also be anyone.

And the answer to that question might define the future of the American left, which has split over race, party politics, and the limits and powers of protesting since two activists took over a podium in Seattle seven days ago.