We seem to be suffering from the loss of teaching logic – not complex “formal” logic, but basic logic as it has existed since the time of Aristotle, especially how to avoid basic logical fallacies.

I claim no expertise in logic myself. Indeed, I often regret the lack of logical instruction in my education. But exposure to even the most basic logical fallacies makes it difficult to tolerate a lot of what passes for argument in current public discourse.

One basic logical error is commonly known as “affirming the consequent.” Someone says, “If it’s raining, then the ground outside will be wet.” Someone else points out: “The ground outside is wet” and from this concludes: “therefore, it must be raining.” This is an obvious logical fallacy. The ground might be wet for any number of reasons – someone might be watering the lawn, for example – rain being only one reason among many for the ground becoming wet.

So, too, in politics we hear arguments that go something like this: “If the president’s policies work, then unemployment will go down. Unemployment has gone down. Therefore the president’s policies worked.” But this too is an obvious logical fallacy. Unemployment might have gone down for any number of reasons. The problem here is one of mistaking correlation with causality. If X comes after Y, this doesn’t necessarily mean X was caused by Y.

There are more high-power lines in some county; there also happen to be more cases of cancer in the same county. Have the high-power lines caused the cancer? It doesn’t necessarily follow. But plenty of people like to jump to that conclusion. We’d need a lot more evidence than mere correlation to conclude there was causality involved.

Another logical fallacy is the ad hominem fallacy, so-called because it is an appeal against the person making the argument rather than against the argument itself. Someone says “2 + 2 is 4″ and the reply is: “But you’re a bigoted homophobe.” Now, it may in fact be true that the first person is a bigoted homophobe (although that would presumably have to be proven, not merely asserted), but even if it were true, it doesn’t follow that 2 + 2 isn’t 4.

A despicable man who cheats on his wife might be quite right when he says that copper conducts electricity; it counts nothing against his argument to point out that he is a terrible man. Terrible men make legitimate arguments all the time, and although we might wish it weren’t the case, absolutely saintly men and women can at times make terrible arguments. Either way, ad hominem arguments – argument attacking the one making the argument rather than the argument itself – are logically fallacious, and it doesn’t take a philosophical genius to see this.

And yet so much of contemporary political discourse is comprised of just such ad hominem attacks. Someone says, “We need to increase taxes to balance the budget” and the response is: “I can see you’re one of those high-spending liberals.” Another person argues that the way to decrease the budget deficit is to cut taxes on investment, and he hears: “You conservatives are always trying to enrich the 1 percent on the backs of the poor.” It doesn’t matter whether the speaker is really a liberal or not, or whether he is in the slightest interested in wealthy people. Attacking an opponent’s character seems sufficient for some people to imagine they’ve defeated an argument.

All logical fallacies are a problem, and if they go uncorrected, serve only to confuse argumentation. But there is, I would suggest, something especially violent about ad hominem arguments. These are not only logical mistakes, they are personal attacks. And as the stakes get higher and the arguments weaker, the more vicious the attacks tend to become. Wives and friends start getting attacked. It turns out you are friends with some notorious liberal. Gotcha! Your arguments are clearly bogus. One of the biggest problems we face in contemporary politics is the degree to which people mistake this pointless give-and-take for actual argument.

I once had a disturbing discussion with a young man who, after some minor back-and-forth, said: “Oh, you’re using logic; I don’t accept that form of Western imperialism.” Not only did his every statement depend upon logic of a basic sort – such as “To deny is not the same as to affirm” – but more tragically, in making this absurd claim, he was insulating himself from any counter-arguments that might have taught him something new.

Similarly, the tendency that frightens me most about current political discourse is the degree to which we have by our ad hominem attacks essentially insulated ourselves from the arguments of others. This is done in many ways, from “I won’t listen to a fascist hater” to “You egg-head intellectuals are never going to convince us that Trump isn’t the right man for president.” Really? Isn’t that just an admission of invincible ignorance? Can you imagine saying to Pope John Paul II or Pope Benedict: “You egg-head intellectuals are never going to convince us that abortion is wrong.” Should we take this as condemnation of them or you?

Egghead intellectuals make mistakes; but then again so do plumbers, cops, and saintly mothers. So let’s forget the ad hominem foolishness and get to the substance of the argument; that we so often don’t helps explain why we increasingly get fistfights instead of dialogue. Attack a person’s arguments, and he can respond with arguments. Attack a person’s integrity or, more ignorantly, his wife’s integrity, and expect something different.

If you’re conservative, not having liberal friends should be counted against you, not for you. The reverse is true for liberals. We need discussion partners of intelligence and good will to help us test our positions as gold is tested in fire.

Either way, responding to ad hominem attacks with more ad hominem attacks only doubles down on dumb.