Plenty has been written about arguments and how they can be bad: sins against good sense are called "fallacies" and there are many lists of them. Some of the more popular fallacies have become household names - ad hominem attacks, the appeal to authority, and everyone's favorite the straw man argument.
Likewise, cognitive psychologists have done much to name and catalogue the various ways in which our minds can decieve us. Under the blanket name of "biases" many of these are well known - there's confirmation bias, cognitive dissonance, rationalization, and so on.
There's a reason why so much has been said about fallacies and biases. They're out there, and they're a problem. When you set your mind to it, you can find them almost anywhere - no matter who you are. This, for example, is written by someone who believes that HIV does not cause AIDS. By most standards, this makes him a kook. And he probably is a kook, about AIDS, but he’s not stupid. He makes some perfectly sensible points about cognitive dissonance and the psychology of science. And here, he offers further words of wisdom:
I have no satisfactory answer to offer, unfortunately, for how AIDStruthers could be brought to useful mutual discussion.
Here’s a criterion for whether a discussion is genuinely substantive or not, directed at clarification and increased understanding: no personal comments adorn the to-and-fro. If B appears not to understand what A is saying, then A looks for other ways of presenting the case, A doesn’t simply keep repeating the same assertions spiced with “Why can’t you…?”, and the like. [Added 28 December: Another hallmark of the non-substantive comments is that the commentator not only keeps harping on the same thing but does so by return e-mail, leaving no time to consider what s/he is replying to; see Burun's admission of suffering from that failing.]
One lesson from experience is that the aim of Rethinkers cannot be to convince the AIDStruthers. It soon becomes a sheer waste of time to attempt to argue substance with them; a waste of time because you can’t learn anything from them, and they are incapable of learning anything from you. Rethinkers and Skeptics should address the bystanders, onlookers, the unengaged “silent majority”. There seem always to be with us some people who cheerfully continue to believe that the Earth is only about 6,000-10,000 years old, and many other things that most of us judge to be utterly disproved by factual evidence.
The lesson here is that you don't have to be right in order to notice that people who disagree with you are irrational, or that much of the opposition to your belief is dogmatic. The sad fact is that stubborness and a tendency to dogmatism are a part of human nature and it's very hard to escape from them; likewise, it's very hard to make a complex argument without saying something at least technically fallacious (that witty aside? Ad hominem attack!)
The point is that none of this matters. If something is true, then it's true even if everyone who believes it is a dogmatic maniac. So it's certainly true even if the only people you know who believe it are idiots. What's the chance that you've argued with the smartest Christian ever, or the best informed opponent of homeopathy? In which case - the fallacies and biases of the people you have argued with certainly don't matter. In an argument, the only thing of importance is what the facts are, and the way to find out is to look at the evidence.
If you're taking the time to name and shame the fallacies in someone's reasoning or to diagnose their biases, then you're not talking about the evidence - you're talking about your opponent(s). Why are you so fascinated by him...? To spend time lamenting the irrationality of your opponents is unhealthy. The only people who have a reason to care about other people’s fallacies and biases are psychologists. Daniel Kahneman got half a Nobel Prize for his work on cognitive biases - it's his thing. But if your thing is HIV/AIDS, or evolution, or vaccines and autism, or whatever, then it's far from clear that you have any legitimate interest in your opponent's flaws. In all likelihood, they are no more flawed than anyone else - or even if they are, their real problem is not that they're making ad hominem attacks (or whatever), but that they're wrong.
So when barely-coherent columnist Peter Hitchens writes in the Daily Mail about wind farms
If visitors from another galaxy really are going round destroying wind turbines, then it is the proof we have been waiting for that aliens are more intelligent than we are.The swivel-eyed, intolerant cult, which endlessly shrieks – without proof – that global warming is man-made, has produced many sad effects.
The point is not that people who believe that global warming is man made are not a cult. They're not, but even if they were, it wouldn't matter. The swiveliness of their eyes or the pitch of their voice is not obviously relevant either.
Of course, if you're out to have fun bashing heads, or writing columns for the Daily Mail, then go ahead. Learn the names of as many fallacies and biases as you can (including the Latin names if possible - that's always extra impressive) and go nuts. But if you're serious about establishing or discussing the truth about something, then there is only one set of biases and fallacies you ought to care about – your own.