The concealed weapons tactic is an effective argumentation technique, particularly useful for a surprise attack in a debate.
It is a somewhat deceptive tactic, but it can be ethically used as a counter-tactic against blatant disinformation, bad-faith arguments, and other deceptive practices.
To explain how it works, let’s say you’re arguing with climate change deniers. They deny that the Earth is warming due to human activity. One of the arguments they use is that even if there is some rise in temperature, it is all explained by variability in solar activity.
Let’s also say that you have proof that solar variability doesn’t account for it. However, rather than using this evidence to immediately refute their BS, you hold it off. You let them dwell on what they think is your missing evidence, and this way they give it a lot more weight.
Quintilian on the Concealed Weapons Tactic
Quintilian, one of the most prominent Roman rhetoricians, explained the concealed weapons tactic this way:
"While the battle still rages, the task of luring on our adversary when he has once committed himself to error, and of forcing him to commit himself as deeply as possible, even to the extent at times of being puffed up with extravagant hopes of success, requires great prudence and skill. It is, therefore, wise to conceal some of our weapons: our opponents will often press their attack and stake everything on some imagined weakness of our own, and will give fresh weight to our proofs by the instancy with which they demand us to produce them."
So there are a few basic elements to this tactic.
First, you hold back some evidence that supports your position. Simply don’t mention it and your opponent will likely assume you don’t have it.
Second, your opponent, mistakenly thinking you don’t have it, will focus on the supposedly missing proof. Now that your opponent has called attention to it, your proof gains much more weight.
Finally, when you bring up the proof, it will have a much more powerful refutational effect. And maybe — just maybe — it will make the misinformation peddlers a little bit more afraid to use bad-faith arguments the next time.
References:
Quintilian, Institutes of Oratory (Book VI, Chapter IV, 17)