If there are any Republicans out there who haven't joined the presidential race, they'll probably be getting in soon — even if a Donald Trump campaign is too much to hope for.

With a remarkable 15 announced or soon-to-announce candidates, including such dynamos as Lindsey Graham and George Pataki, there's still one thing we haven't seen yet: the Republican candidates attacking each other. There's been a vague insinuation here and an implied criticism there, but no real verbal fisticuffs to speak of. But worry not: The negativity is coming, and when it does, it will come fast and hard.

The first contest of the primary season is still eight months away, but as it gets closer, each candidate will start seeing their relative place in the contest come into focus. And the more it does, the greater the incentive will be to take potential opponents down a peg.

Whoever's in front (if anyone actually moves to the front) will want to beat back challenges from below. Those behind will want to punch upward to pull down the leader. And everyone will want to strike out laterally to make sure they're the ones with a chance to climb upward.

Once the primaries begin, desperation will set in for some candidates, which inevitably leads them to sign off on nastier rhetoric and advertising than they ever thought they'd engage in. If all goes well, it'll be a spectacle of insults, attacks, and character assassination. Should be great fun.

Lest you think I'm being too cynical, let's not forget that just because you're criticizing another candidate instead of touting your own virtues doesn't mean you aren't contributing something valuable to the debate. There are reasons to vote for candidates, but there are also reasons to vote against them — and if their opponents don't tell us, we might not learn about them at all. As I heard a political consultant say once, no candidate is going to tell voters, "I hope you vote for me, but before you do, there are a few things you ought to know..." If Jeb Bush's diligent opposition researchers discover that Scott Walker once shot a man in Reno just to watch him die, then we should hope they'll share that information with the rest of us.

So when the race gets adversarial, we shouldn't reflexively condemn the fact that the candidates are criticizing each other. It's important to remember that when candidates are being "positive," they're just as likely to be feeding the voters pabulum. In fact, research on political advertising I did in my former life as an academic showed that positive ads were less likely to concern policy issues and more likely to contain inaccuracies than negative ads. What's more helpful to voters: showing them a soft-focus picture of my family and sharing my deep love for America, or telling them that the numbers in my opponent's tax plan don't add up?

There are better questions to ask than whether the candidates are being "positive" or "negative." Is the criticism they're making accurate and fair? Does it tell us something meaningful about the candidate being criticized? Is it relevant to the job he or she will be doing as president? If the answer to those is yes, then there's nothing wrong with it.

For instance, if I were running against the newest entrant, Lindsey Graham, I might note that while he touts his experience in foreign policy as the foundation of his campaign, on foreign policy questions he's perpetually wetting his pants in terror, which has some disturbing implications for his decision-making as president. Is there anything illegitimate about that?

But nobody's naïve here — we know that the accurate, meaningful, and relevant criticisms are likely to be fewer than the ones charging candidates with sins like insufficient ideological purity or dangerous flip-floppery, not to mention the ones that delve into the candidates' personal lives. And with so many candidates, the chances that the race will devolve into a thunderdome of pummelling and recrimination are pretty high. But in and of itself, that doesn't mean the Republican primaries will be any less edifying than they would be if they were entirely civil and polite. At least it'll be entertaining.