Portmore's book is aptly titled. It is about oughts, options, and their relation. It is clear, careful, and chock full of arguments. On the downside, these virtues did tend to make the book dense. Without careful study, it is easy to get lost in the details. My aim in this review is to give an informal presentation of some main points, which hopefully will whet your appetite for the technical details.

The book is primarily a work of what I call structural metaethics. Different normative theories disagree about what ultimately matters. Maximizing act utilitarianism holds that what ultimately matters is just net aggregate well-being. One version of Kantianism holds that what ultimately matters is just autonomy, and so on. Portmore abstracts away from such disagreements. He is focused on how a normative perspective, such as morality or practical rationality, must be structured, especially insofar as it issues verdicts that one ought to do something. His thought is that we can resolve some normative puzzles simply by getting these structural issues clear (cf. pp. 277–8).

Chapter 1 argues that what you ought to do is a function of how good your options are with respect to what ultimately matters, whatever that happens to be. (Hereafter I often suppress the qualifier “with respect to what ultimately matters.”) As a first pass, you ought to φ just when φ is your best option. This first pass captures an intuitive relation between oughts and obligations: you ought to do whatever you are obligated to do. When you are obligated to φ, it is the only option that is sufficiently good, and so it is also the best option. Hence, the first pass entails that you ought to do it. On the other hand, when there is more than one sufficiently good option, then what you ought to do can go beyond what you are obligated to do. Perhaps all you are obligated to do is send your mother a card for her birthday, but you ought to do even more and send her flowers too (pp. 10–11).

The first pass of “ought” needs refinement. For Portmore, an “option” is just something that is assessable for deontic status, e.g., assessable as (im)permissible or what ought (not) to be done (p. 13). There is nothing in this definition that tells us that all options are created equal. Perhaps some options are privileged, such that they get their deontic status in virtue of how good they are in comparison to the alternatives. And perhaps some options get their deontic status in a derivative way, depending on how they relate to the privileged options. To make room for such a possibility, we should accept:

(My statements of Portmore's key principles ignore some technical details and are not official.)

The rest of the book largely focuses on what our options are, which options are privileged, and how options are ranked in terms of what ultimately matters. To identify our options (as Portmore defines “options”), we need to identify which things have deontic status. In Chapter 2, Portmore argues that deontic statuses play two important roles, and these roles constrain which things can be options. First, deontic statuses are action-guiding or “directive” (p. 50). Action-guidance is felicitous only if the guidance concerns something under your control. Morality does not demand that you end world hunger, because it is out of your control whether world hunger is ended. In other words, the action-guiding role of deontic statuses presupposes that options are within your control.

Certain deontic statuses, such as obligations, also have a second role: they are inculpatory. That is, if you do not do what you are obligated to do and lack a suitable excuse, then you are blameworthy. But you are not blameworthy – or, more generally, accountable – for doing something when that thing is not under your control. Hence, the inculpatory role of deontic statuses also presupposes that options are within your control.

What does it take for something to be within your control? It requires more than that you can do something, because you can do some things by sheer luck. I am terrible at golf. We are all astonished when, on number 18, I hit a hole-in-one. Since I did hit a hole-in-one, I could have hit that hole-in-one. But it was not one of my options, because hitting a hole-in-one was not in my control. It was pure luck (pp. 70–1).

Chapter 3 further clarifies the operative type of control. You might think that an option is something you can do in the situation just by choosing. This would explain why I do not have the option to hit the hole-in-one; while I can do it, I cannot do it just by choosing. The problem with this suggestion is its focus on volitional control. I generally cannot choose which beliefs, desires, and intentions I have, and yet I can still be obligated to believe that the earth is spherical, to desire the success of my children, and to intend to go on a diet. Having such beliefs, desires, and intentions is in my control only insofar as I can have such attitudes in response to (apparent) reasons. The moral is that, for something to be an option, it must be in my rational control (99–100), and it must be in my rational control now and not just in some future time (§3.1). Together, then, chapters 2 and 3 defend:

Now that we know what our options are, Chapter 4 provides an account of which options are privileged. Professor Procrastinate is invited to review a book. His overall best option is to accept the invitation and complete the review. Yet if he accepts the review, he predictably will procrastinate and never complete it, which is the worst outcome. This seems to give us two conflicting verdicts: (1) the professor ought to accept and complete, but (2) it is false that he ought to accept. What gives?

Notice that the two conflicting verdicts concern options at differing levels of specificity. Accept and complete is more specific than accept, which does not specify whether the review is completed. Portmore holds that this difference matters:

When we apply maximalism to the Professor Procrastinate case, we find that the second verdict is spurious. Accept and complete is the best maximally specific option, so that's the maximal option that he ought to do and verdict (1) is true. Since the nonmaximal option accept is entailed by the privileged option that ought to be performed, verdict (2) is false and the professor ought to accept (cf. p. 126).

At least, that's how things go if the professor can repress his procrastination. If the professor's procrastination is irrepressible, then he does not have rational control over whether he completes the review, and thus accept and complete is not even an option. On this way of understanding the case, the first verdict is false and the second is true, i.e., it is false that the professor ought to accept (pp. 156–61).

By now, Portmore has separately defended rationalism and maximalism. Chapter 5 argues that the combination of rationalism and maximalism has various further virtues. In Chapter 6, reasons come to the fore. Opt for the Best is an account of ought in terms of what ultimately matters. A natural thought is that what ultimately matters should correlate with reasons, so that the following claim is also true:

A main point of this chapter is to extend maximalism about options to maximalism about when we have most reason.

Chapter 7 argues, roughly, that privileged options are ranked, not on the basis of how good they actually are, but on the basis of their expected utilities. That is because sometimes, at the time of the decision, it is indeterminate (i.e., there is no fact of the matter) about what the actual outcome will be. The conclusion, Chapter 8, provides a helpful summary of the book's arguments, especially those in Chapters 2–7. If I have done my job, you will have a taste of the book's arguments but be left wanting more. The only thing to do now is read the book!