Suppose that you and I want to get together for lunch. We agree on a place and time − El Burrito Gordo at noon on Wednesday. To get there on time, I must leave my house at 11:00 am, and so that’s what I do. But suppose that, as I’m driving down a small country road, I come across an accident. There’s a car in a ditch, badly mangled, and a person lying next to it, obviously injured pretty seriously. I look around and see no one else. I think of calling someone on my cell phone but find that I can’t get any signal. So, now, what to do? If I take the time to help the injured person, I’ll miss our lunch. If I keep our date, I’ll leave him unaided.

This simple story brings out a couple of important points. First, I can have a good reason (a good moral reason) to do one thing and also have a good reason (again, a good moral reason) to do another thing, and yet be unable to do both things. In the story, I have a good reason to give aid to the injured person (he needs my help) and also a good reason to meet you (I agreed to do so), and yet I am unable to both help him and meet you. Secondly, what I ought to do all things considered is presumably to act in accordance with the strongest reason that I have. In the story, the reason to help the injured person is likely to be stronger than my reason to keep our date, so what I ought to do all things considered is not to meet up with you but to help him instead. (Of course, we can easily imagine a different case in which we would reach a different verdict − one, for example, in which the injury is minor but meeting on time is for some reason very important.)

Let me now introduce some terminology that reflects the points just made.

A distinction is to be drawn between (a) what is overall morally obligatory, morally right, or morally wrong, on the one hand, and (b) what is prima facie morally obligatory, morally right,  or morally wrong, on the other.

As for (a):

To say that an act is overall morally obligatory, or that one has an overall moral obligation to perform it, is to say that there is conclusive moral reason to perform it, that is, that from the moral point of view one must do it, all things considered.

To say that an act is overall morally wrong is to say that there is conclusive moral reason not to perform it, that is, that from the moral point of view one must not do it, all things considered.

To say that an act is overall morally right is to say that it is not overall morally wrong, that is, that from the moral point of view one may do it, all things considered.

(The difference between “morally obligatory” and “morally right” is this: if an act is morally obligatory, it is the only morally right thing to do. However, an act can be morally right without being morally obligatory, since there might be some other morally right option that one could choose instead; in such a case, the act may be said to be “morally optional.”)

As for (b):

To say that an act is prima facie morally obligatory, or that one has a prima facie moral obligation to perform it, is to say that there is some moral reason to perform it.

To say that an act is prima facie morally wrong is to say that there is some moral reason not to perform it.

To say that an act is prima facie morally right is to say that there is some moral reason to perform it. (You will have noticed that this definition matches the definition for prima facie moral obligation. That is deliberate. There is in fact a subtle distinction to be made here, but it’s not one that we need worry about.)

Notice that, by definition, an act cannot be both overall morally obligatory (or even just overall morally right) and overall morally wrong. However, since it can happen that there both is some moral reason to perform an act and also some moral reason not to perform it, an act can be both prima facie morally obligatory (or prima facie morally right) and prima facie morally wrong.

Notice also that moral reasons vary in strength; some are stronger than others. Some acts (e.g., causing someone severe harm) may be seriously prima facie morally wrong while others (e.g., causing someone minor harm) are not so seriously prima facie morally wrong. Thus, in the little story I just told, I had a prima facie obligation to meet with you, but I had a stronger conflicting prima facie obligation to help the injured person.

An act is overall morally obligatory if the moral reason or reasons to perform it are stronger than, i.e., outweigh or override, whatever moral reasons there are not to perform it. Thus, in the story, my overall moral obligation was to help the injured person and not meet with you.

An act is overall morally wrong if the moral reason or reasons not to perform it are stronger than, i.e., outweigh or override, whatever moral reasons there are to perform it. Thus, in the story, it would have been overall morally wrong for me to meet with you.

The stronger a moral reason (a prima facie moral obligation) to do something is, the more difficult it will be for some contrary or conflicting moral reason (or prima facie moral obligation) to override it, and so the more likely it will be that it would be overall morally wrong to fail to satisfy it.

***Here is a good place to stop and consider Questions 12, 13, and 14 on the Practice Questions for Module 1.***

Instead of saying that an act is prima facie morally obligatory, we may say that there is a prima facie moral duty to perform it. There is a famous thesis, according to which moral rights of a certain kind (often called “claims”) correspond with prima facie moral duties as follows:

The Correlativity Thesis:
X has a moral right against Y that Y do (or not do) A just in case Y has a prima facie moral duty to X to do (or not to do) A.

This thesis will come in handy later when we talk specifically about certain moral rights.

The Correlativity Thesis makes the following kind of claim: P “just in case” Q. Here, “just in case” is supposed to be understood as saying that P is equivalent to Q; that is, that P and Q “come to the same thing”; that is, that if P is the case, then so is Q, and if Q is the case, then so is P. To see what, according to the Correlativity Thesis, the link between rights and duties comes to, consider these two examples.

For our first example, suppose that Brown (Brown = X) has a moral right (sometimes called a “right to life”) against Green (Green = Y) that Green not kill him (killing = A). Then, according to the Correlativity Thesis, Green has a prima facie moral duty to Brown not to kill him.

For our second example, suppose that Smith has made a promise to Jones to meet him and that, as a result, Smith (Smith = Y) has a prima facie moral duty to Jones (Jones = X) to meet him (meeting = A). Then, according to the Correlativity Thesis, Jones has a moral right against Smith that Smith meet him.

Notice that, given the Correlativity Thesis, it can happen that it is sometimes overall morally right to fail to satisfy someone’s moral right. This may sound odd, but it’s a very important point. Even if Jones has a moral right against Smith that Smith meet him, it might be overall morally wrong for Smith to meet Jones − he might, for example, be faced with an emergency (such as the one described in the story above) that provides him with a stronger reason to do something other than meet Jones, even though Jones has a right to Smith’s meeting him. This shows that determining who has rights and what rights they have is not always all that is required for figuring out just what ought, overall, to be done. How strong the rights in question are will also be relevant. We’ll see this important point coming into play in, for example, our discussion of the morality of abortion.

***Here is a good place to stop and consider Question 15 on the Practice Questions for Module 1.***