Once you have a basic understanding of the policy possibility and the reasoning behind it—-what it says and why it says it—-the next step is to ask yourself whether and to what extent it is likely to address the concerns that motivate it in a way that is consistent with the beliefs, values, goals, and interests that underlie it.

The question, in short, is whether and to what extent it is likely to do what it is supposed to do.

In order to answer this question, you will once again need to approach the possibility on its own terms—-or, in other words, by provisionally accepting the validity of the concerns, beliefs, values, goals, and interests that motivate it. Thinking about whether and to what extent a possibility is likely to work on its own terms will develop and deepen your understanding of the possibility itself. But it will also help you to evaluate it. For the concerns, beliefs, values, goals, and interests that motivate a policy possibility provide the touchstone for evaluating it on its own terms.

If you think that the possibility is likely to what it is supposed to do, and not by chance but for the reasons that it is supposed to do it, then you will probably think that it is a sound policy possibility. You will, of course, still have to ask yourself whether or not you share the concerns, beliefs, values, goals, and interests that motivate it in order to decide whether or not to support it. But if you think that it is not very likely to work in the way it is supposed to, then you will probably not regard it as a sound policy possibility even if you do share the concerns, beliefs, values, goals, and interests that motivate it.

But how can you know whether a policy possibility will actually address the concerns that motivate it? How can you know whether it is consistent with the beliefs, values, goals, and interests that underlie it? How, in other words, can you know whether and to what extent it is likely to do what it is supposed to do?

Most people who put forth policy possibilities do so with the idea that the possibility will have ‘positive’ effects—-at least in the eyes of those who share their concerns, beliefs, values, goals, and interests—-if everything goes according to plan. But in order to evaluate a policy possibility, you need to think not just about what will happen if everything goes according to plan, but also about the likelihood of something not going entirely according to plan, and about the likely consequences of something going wrong.

You need to think, in other words, about the possible unintended consequences of adopting the policy possibility, and about the likelihood of their coming true.

‘How will this policy possibility be implemented if everyone embraces it and everything goes just right?’ may elicit one sort of answer. But ‘How, given our real-world political realities and economic necessities, is it likely to be implemented?’ may elicit another. The same holds true for ‘What impact is this policy possibility supposed to have on individuals, groups, institutions, and society at large?’ and ‘What impact is it likely to have, given the likelihood of something going wrong, and given the way it is most likely to be implemented in the real world?’

We cannot, of course, know any of these things with any real certainty. So we will always have to make a judgment, or hazard a guess, about them. And we may, of course, always be wrong. But this is true of almost everything and it is no reason not to make a judgment. For here, the point of asking these questions is not to reject a policy possibility because ‘there may always be unintended consequences’ or because ‘something may always go wrong’. It is to place ourselves in a better position to evaluate the possibility on its own terms.

If, after asking yourself these questions and thinking about them carefully and talking about them with others, you find yourself thinking that there may be some unintended consequences and things might not go entirely according to plan, but that the possibility is still more likely than not to work in the way intended—-then you can conclude that it is sound policy on its own terms. In that case, you will still have to decide whether or not you share the concerns, beliefs, values, goals, and interests that motivate it—-whether, in other words, it is sound policy on your terms. But if, after asking yourself the same questions and thinking about them just as carefully and talking about them with others, you find yourself thinking that there are just too many things that could go wrong, and that the consequences of their going wrong may all too easily prevent the possibility from achieving its goals—-that they contradict your beliefs, do not reflect your values, and even run counter to your interests—-then you may conclude that the possibility doesn’t even work on its own terms and that you need to look somewhere else if you share the concerns, beliefs, values, goals, and interests that motivate it.