As a matter of logic, of course judging an argument by it’s merits is the only way to go. There is one major problem however, most of us simply aren’t in a position to judge an argument by its merits, and given a skilled peddler of horseshit, attempting to judge an argument by its merits can easily lead us in the wrong direction thanks to what Julian Sanchez calls the “one way hash” argument.
These arguments are relatively easy to make, and just complex enough that they are both intelligible and intuitive to the layman. Refuting these arguments by contrast takes far longer, as one will likely have to explain a whole series of preliminary concepts before it’s really possible to explain why the talking point is wrong. Furthermore the horseshit peddler is only bound by what is plausible, while his opponent is bound more restrictively by both what is true, and what is known. This leads to a situation when laypeople who attempt to judge an argument by its merits are more likely to get it wrong.
Obviously, when it comes to an argument between trained scientific specialists, they ought to ignore the consensus and deal directly with the argument on its merits. But most of us are not actually in any position to deal with the arguments on the merits…
Give me a topic I know fairly intimately, and I can often make a convincing case for absolute horseshit. Convincing, at any rate, to an ordinary educated person with only passing acquaintance with the topic. A specialist would surely see through it, but in an argument between us, the lay observer wouldn’t necessarily be able to tell which of us really had the better case on the basis of the arguments alone—at least not without putting in the time to become something of a specialist himself. Actually, I have a possible advantage here as a peddler of horseshit: I need only worry about what sounds plausible. If my opponent is trying to explain what’s true, he may be constrained to introduce concepts that take a while to explain and are hard to follow, trying the patience (and perhaps wounding the ego) of the audience.
Come to think of it, there’s a certain class of rhetoric I’m going to call the “one way hash” argument. Most modern cryptographic systems in wide use are based on a certain mathematical asymmetry: You can multiply a couple of large prime numbers much (much, much, much, much) more quickly than you can factor the product back into primes. A one-way hash is a kind of “fingerprint” for messages based on the same mathematical idea: It’s really easy to run the algorithm in one direction, but much harder and more time consuming to undo. Certain bad arguments work the same way—skim online debates between biologists and earnest ID afficionados armed with talking points if you want a few examples: The talking point on one side is just complex enough that it’s both intelligible—even somewhat intuitive—to the layman and sounds as though it might qualify as some kind of insight. (If it seems too obvious, perhaps paradoxically, we’ll tend to assume everyone on the other side thought of it themselves and had some good reason to reject it.) The rebuttal, by contrast, may require explaining a whole series of preliminary concepts before it’s really possible to explain why the talking point is wrong. So the setup is “snappy, intuitively appealing argument without obvious problems” vs. “rebuttal I probably don’t have time to read, let alone analyze closely.”
If we don’t sometimes defer to the expert consensus, we’ll systematically tend to go wrong in the face of one-way-hash arguments, at least our own necessarily limited domains of knowledge. Indeed, in such cases, trying to evaluate the arguments on their merits will tend to lead to an erroneous conclusion more often than simply trying to gauge the credibility of the various disputants. The problem, of course, is gauging your own competence level well enough to know when to assess arguments and when to assess arguers. Thanks to the perverse phenomenon psychologists have dubbed the Dunning-Kruger effect, those who are least competent tend to have the most wildly inflated estimates of their own knowledge and competence. They don’t know enough to know that they don’t know, as it were.
This is exactly my post on why I accept anthropogenic global warming focused on the overwhelming consensus rather than the specifics of the argument itself.