You and I started learning how to get what we want from other people as soon as we were born. And all those crucial years of learning were before we had the cerebral capability to persuade by giving good sound reasons why it was in the person's best interests to do what we asked.
During these formative years, we formed the habit of getting what we want by non-reason-giving methods: By wheedling, by being sneaky or charming, by making people feel guilty, by subtle suggestion or obvious hinting, by nonverbally threatening to get angry, by asking again and again until people give in just to shut us up, and so on. The habits we formed, the methods of persuasion you and I learned to use were almost never a simple straightforward explanation of why the other person will be glad to do what we ask. And yet that is the best way to get what you want from people, and I'll tell you why.
To begin with, to use this method, you have to think about it. And in order to answer the question, How is this in their best interests? you have to discover if it is, in fact, in their best interests. If it isn't, you have no right to ask it. If it's not in their best interests, the person should refuse you. It is immoral of you to ask someone to do something that isn't good for them.
Even if the reason you give is simply it'll make me want to do you a favor when you need one, as long as that's true, it's a good reason. So the first reason I think you should use this principle is that it'll weed out any immoral requests you have.
Second, it's honest, so you'll be happier getting what you want using this method. When you're honest, you don't have to do things that make you unhappy — things like lying, being sneaky, throwing a fit, getting angry, making someone feel bad, being subtle or indirect — these things are unpleasant, uncomfortable, and don't produce enjoyment or satisfaction, even when they succeed. Honest methods produce less stress.
And the third reason this is a good way to get what you want is because it works better in the long run than any other method. You will get more of what you want, over time, with this method than with any other.
People respect honesty, and if you're honest and straightforward with people, they will learn to trust you. Then when you say I think you ought to do this because it's in your best interests, they will not shut you off like they do the tricky and underhanded persuaders (as soon as they catch onto the game). When you speak, your words will carry more weight. The people who know you will listen to you.
Also, we have a tendency to use all the indirect, roundabout ways to persuade, not because it's better than being direct, but because we've been in the habit of it since we were two years old. When you stop and pay attention to it, I'll bet you're surprised at how often you know good reasons that someone should do something, and you've been "trying to get" them to do it for a long time, but you've never actually told them why you think they should. It's kind of funny, really. It would be a lot funnier if it weren't so tragic.
You don't even have to "be persuasive" for this to be effective. In other words, you don't have to be charming or coy or clever. You can simply think it through and then say it simply: "I've read a lot of studies, and there seem to be more every day, that show people live longer and have less cancer and heart disease when they eat lots of vegetables. I want you to live a long time, so I think you ought to eat more vegetables."
Imagine someone saying that to you. Wouldn't it carry some weight, if only because of it's simplicity and directness? Now, of course, there are some people who would respond with "Yeah, whatever." They won't be persuaded. This method won't get you everything you want. It isn't perfectly effective, it is only more effective than any other method.
Let me be clear about this, in case you think more manipulative methods may work better. Yes, a more manipulative method may get this one thing with this one person better this one time. But your life is an ecology. Dishonesty to another person or sneakiness or phoniness effects your life beyond that one encounter. It's like the difference between a salesman who wants repeat business, and a salesman who comes into town to sell as many of his shabby doohickies as he can before he moves on to the next town. Sneaky, manipulative, dishonest methods will not create repeat business. It will ruin the reputation of the salesman.
If you are in a close relationship, the dishonesty will gradually erode your feelings of affection for each other and you'll grow more and more distant. This is a major cause of "falling out of love:" people are manipulating each other in dishonest or phony ways. Being something other than what you are is a form of lying, and when you lie, the other person doesn't know you as well, and so they are more distant from you, less intimate, less close. Same goes for you. You're not as much in love because you're not as open. You're somewhat closed off (to prevent a discovery of what you are really up to).
Honest, straightforward ways of dealing with people prevent you from feeling anxious about what others would think if they found you out, or anxiety about what you feel you are doing to someone when you take advantage of them, or negative feelings in general that these childish, emotionally-manipulating methods produce in everyone involved.
Practice this in your head beforehand. Think of something you want from someone else. Think of something you want them to do. Then imagine telling them straightforwardly why you think it's in their best interests to do it. Think of as many good reasons — good from the point of view of the other person — as you can, and imagine telling that person directly, without any coyness, game-playing, or emotional manipulation.
Now think of something else you want someone to do. And go through it again. Think up all the reasons the other person would want to do it. And imagine telling them.
You'll need to practice because you're not in the habit of it. You've got other habits that will tend to get in the way. Practice it with every little request you have for people. Make it a habit, and it will make a difference to you for the rest of your life.
Adam Khan is the author of Principles For Personal Growth, Slotralogy, Antivirus For Your Mind, and co-author with Klassy Evans of How to Change the Way You Look at Things (in Plain English). Follow his podcast, The Adam Bomb.