I have one model of persuasion I would like to explore today and one I would like to reject. I am sure these models have names that are known to people who study persuasion, but I don’t know what they are and today, I really don’t care.
The context in which I have been hearing the model I want to reject is the present substantial and growing rejection of President Trump’s leadership. That’s just the context. Someone is open in principle to the case that President Trump has failed badly in his duties. She, to assign gender arbitrarily, is open to evidence that you are going to present. Here’s the question. I think it is a bad question, but let’s start with it. How much evidence is it going to take?
The major flaw in that question is that it presupposes that more evidence is going to be better than less evidence. That’s true up to a point and then it stops being true. Let’s examine some analogies.
How heavily should a state tax tobacco products? The advantage to the state of taxing tobacco products is that: a) the state gets to keep the money and b) there is a disincentive (higher cost) to using tobacco products. So you would think that the higher you raise the tax, the better. Except that that really isn’t true. There is a level of taxation at which covert means of importing tobacco (black market) become profitable and at that point, you start losing the money you wanted to raise. There is a tipping point. The higher the taxes, up to that point, the more you make; after that point, you start making less. Or, briefly, “more” is worse.
The alternative model presupposes that there is no response. Nothing in the alternative model suggests a tipping point after which “more” is worse. Imagine a wall that resists the pressure you are putting on it. You put X pressure on it; then X + 1; then X + 2. Finally the wall breaks down
In the beginning, I introduced a Trump supporter, a woman, whom I am trying to persuade. Being unsophisticated and also deeply committed to the data I have, I am trying to persuade to abandon her case that he has been a good president.
So I say that President Trump has asked for and received the help of foreign spy agencies in defaming his opponent. I have five pieces of evidence that is true. I say that President Trump has led the country poorly in response to the pandemic. I have five pieces of evidence. I say he has begun and pursued an unnecessary and costly trade war with China. I have five pieces of evidence. The evidence is all really good. Irrefutable, really. So I ought to win this one, right?
She seems receptive to the first point. President Trump has been receiving aid from the Russians. She accepts the first argument in support, and the second, and…eventually…the third. But something is starting to go wrong. Her agreements are slower and seem more ambivalent. If I knew anything at all about the signs of the tipping point, I would pay attention to them. But I don’t. I’m just increasing the logical force, imagining that she has no options.
But she does, of course. She can just get up and leave, which the wall could not. She could deny the accuracy of the evidence by making the evidence-gatherers self-interested.  Finally, she could reject me, her friend, as a source of information about President Trump. I have cherrypicked the data; I have a hostile emotional bias; I am just trying to embarrass her.
This is like the topic of evolution is some southern school districts. If you try too hard to
establish the “truth,”  you show the problem. You show how the theory of evolution provides efficient solutions to that problem and you prepare to move on. But the responses of the class become slower and more ambivalent. But you proceed because you have Science on your side and what choice to they have?
But you are putting at risk the relationship of trust these students have in their parents and in the local Baptist church, where all their friends meet. That’s a lot of emotional drag. These students are not like the wall; they are like the black market in tobacco.
So they respond by trying to separate “fact” from “theory.” This is deadly. In science, it isthe facts that support the theory. The school board makes up little stickers that say (Evolution is a theory, not a fact) and stick them in the text where assertions about the adequacy of the evolutionary point of view are asserted. Page after page, lies are told about the relationship of facts to theories.
And if that separation doesn’t work, they can move on to the denial of science broadly. As President Trump said on his recent visit to California, “Science really doesn’t know.”  Failing that, they can “home school” their children using anti-evolution biology texts.
When you get to that point, you realize that you should have stopped earlier. The conditions that prevail after the tipping point has been passed are: a) the whole set of arrangements for weighing evidence are are scrapped, b) the relationship between you and the person who trusted you to be fair is damaged, and c) they might just leave and set up institutional arrangements that will prevent evidence from being presented at all. Those are really bad outcomes. Everyone loses; even the ones who think they won.
What to do.
First, accept the tipping point model. When you push beyond that, you yourself become the point at issue and when that happens you will lose the argument and possibly the relationship.
Second, make room for a little time to adjust to the topic. The first response you get is partly skepticism about the information and partly wariness of you as a presenter, but it may be partly just the novelty. She says, “I have never heard anyone say that about the President before.” That’s three separate stresses on the listener, but the last one may just dissipate on its own. By the next time you talk—and if you don’t bully her, there may well be a next time—it won’t be new anymore and there will be only two stresses. And the two remaining stresses may have weakened as well.
Third, agree with her as much as you can. There is very little to be gained in identifying a political figure that is important to her as “evil.” If you can share a goal with her—protecting the intelligence services of the United States—you can reduce the argument to the best way to do that. Reducing President Trump’s mistakes to “understandable failures” might be a good thing to do first. It establishes that they are failures and it sustains the relationship you have with her. It moves less quickly to the tipping point. You can come back next time to question just how “understandable” they are.
Finally, don’t gloat. Gloating makes the discussion a zero-sum game. Everything that makes her feel bad, makes you feel good. She experiences the pain you are causing her—which is bad enough—but if she also experiences the pleasure you take in inflicting that pain, she may leave the discussion and the relationship on those grounds alone. A point that you make, sympathizing with her about how hard it is to really believe the corruption is that widespread, does put you on one side and her on the other but only factually. Emotionally, you are—or could be—on the same side. And if you can’t feel about the issue the way she does, you can still feel about her emotional response the way she does.
The point is this. If there is a tipping point—a point at which you become the issue—then you need to understand that there will be no more persuasion when you pass it. If you are interested in persuasion, you need to respect that. There are things you can do to move the tipping point a little further away. Sometimes these will be costly to you, but you have to remind yourself about what you are trying to do and to do the things that will help you.
Make the case. Make it repeatedly. Don’t gloat if you’re winning. Save the relationship.
 This does not challenge the data themselves; only the motive in collecting the data. It’s not a refutation, but it is always available in time of need.
 “Truth” is not a viable concept in scientific writing. There are theories that are well supported and others that are poorly supported. Sometimes, as in the case of evolution, the support is so deep that you just start with it as a presupposition. But, of course, “presuppositions” aren’t true or false. They are just a good place to start.
 There is the temptation to ask what the alternative is, but I have resisted that so far.