It's a useful exercise to get overly precise and note that "All lives matter" but for most of us many don't matter much. My summer jobs in college were mostly lab work, and in microbiology labs I routinely autoclaved bacteria and killed organisms by the billions — and in the case of the TB bacilli took some grim satisfaction doing it. Working in a classic physiology lab in gastroenterology, I killed many rats, for which I feel vaguely guilty, and also dogs, one cat, and a rabbit or two — which contributed a bit to my later decision to do without eating mammal meat.So don't tall me "All life is sacred" if you're eating a hamburger or, for that matter, a carrot. People who talk that way either don't consider cows or carrots *really* alive or are arrogantly using a "clipped form" where "life" and "lives" is limited to humans — which is another way of denying real life to organisms we significantly call "sub-human."So obviously just about anyone but a fanatical Vegan or — and more so — a devout Jain makes distinctions about which lives matter enough to seriously influence their behavior toward them, most especially which lives can be taken casually, with, as we say, "no more concern than you would swat a fly," and which deaths can be ignored or mildly enjoyed: as in most eating and sanitizing and a lot of hunting and fishing.What's at stake is our "circle of concern": how far out we care about living beings from self to family and friends and pets to tribe and fellow citizens ... and whether or not the circle of at least abstract, intellectual concern includes big parts of the human species.The sentence "All Lives Matter" should be rejected out of hand because most of us just don't mean it. Certainly not for bacteria nor insects that bother us nor rats nor lambs nor steers; for many, the lives of men convicted of murder don't matter much, and many can rejoice in the deaths of enemy combatants. So we can reject the formulation "All Lives Matter" on the great principle of argument, "Cut the shit."If you want to revise that to "All Human Lives Matter," you need to admit that some matter to you a whole lot more than others, and that that's okay. And then we get to just who(m) we see as fully human and whom we see as really important — and that is where "Black Lives Matter" becomes a very important assertion.