It is a conceit of modern liberalism that the main way people change is that they are presented with "good arguments" against the way they have been living or the decision they have been making, and therefore change it.
This is nonsense. (We we'll get to why liberalism chooses to embrace this nonsense later, perhaps tomorrow.)
Plato described the importance of the periagoge, the turning around the psyche, in the pursuit of philosophy. One could not successfully pursue philosophy, per Plato, unless one had experienced this turning around of the psyche, away from the shadows and towards the light. Why would this be?
I'm going to explain this in a Buddhist framework, because today, that is the one I feel like working with. For Buddhists, the person who has not undergoing the turning around is living in samsara, a world of illusions created by the ego. Their will is directed towards achieving the fleeting satisfactions available in the world of samsara. And reason is the servant, not the master, of the will. And thus, the person living in samsara will direct their reason towards:
1) Figuring out the means of achieving their samsaric ends; and
2) Justifying why those ends are really the ones worth pursuing.
Given this set of directions, it should be easy to see why an argument suggesting that the person is pursuing an unworthy end is worthless: their reason has been given the task of justifying that end, not of determining whether or not it is justified. The reason here is like an army given the job of defending a hill: arguments that the hill is not worth defending are understood as tricks, as attempts to capture the hill. Reason will seek, not to consider whether they are good arguments that might be decisive, but to defend the hill from their assault. That, after all, is the task this person's reason has been assigned!
If you have ever tried, say, using argument to convince a friend, who is in the throes of lust, that it is not a good idea to seduce his neighbor's wife, you may have a sense of what I am talking about here. Caught up in a samsaric desire, your friend is "immune to reason": in fact, his will has deployed his reason like an advance army clearing the territory of obstacles. It utilizes a bewildering variety of defenses against your attempts to dissuade your friend: "My neighbor treats her like crap!" "Marriage is just an outdated convention!" "Monogamy is unnatural to human beings!"
The point is not whether any of these statements are true or false: the point is that they are not being used in a search for the truth. They are weapons, being used to seize a strategic objective.
In Buddhism, the turning around of the psyche is characterized as the embrace of the dharma, the way of truth. The will turns away from ego-driven desires and towards the "right path." And now, with the will directed towards truth, philosophy is possible, since the will now directs reason towards finding out what is universally true, rather than finding out what aids the fulfillment of samsaric desire. And now, after the periagoge, arguments among two followers of the dharma about whether it is right to sleep with your neighbor's wife might get somewhere, since both have wills that orient their reason towards seeking the truth of the matter, rather than seeking to defend the pursuit of what the ego wants anyway.
But before the periagoge, arguments are of almost no use in this regard. (They will work fine, of course, when they are about the practical means of achieving some desire: whether I-95 or I-81 is a better road to take to get to Washington.) Emotional appeals, the force of personality (that is why Plato held personal instruction far more important than his writings), personal example, works of art: all of these are far more effective than arguments at changing the will. If you doubt me, ask yourself: What did Jesus focus on: philosophical arguments about moral behavior, or parables, and the performance of miracles?
(The above way of putting things has been inspired by my recent reading of Claes Ryn's Will, Imagination, and Reason.)