EgyptAir Flight 804's downing is a tragedy. But we still don't know what kind of tragedy. While Donald Trump's certainty that it was a terrorist act may assure some, and could even be accurate, this isn't how investigations like this work. Theories serve only as a way to guide this investigation, but it is facts that will tell us what actually happened. And that matters not simply for the future safety of the global aviation network, but for the stresses on America's own aviation apparatus.