First, a little explanation of NNL. NNL derives specific moral/practical norms by positing two things:
- (1) A set of basic goods--things that are intrinsically good/valuable/worthwhile for humans to pursue. So, they are always "worthy of pursuit." In other words, they are always "to-be-pursued." Also, the basic goods can make immediately intelligible one's action, and are thus reasons for action. This is very important: The basic goods are the fundamental reasons for action; the fundamental "building blocks" of practical rationality. Examples include knowledge, life, friendship, aesthetic experience, and excellence in play.
Let's consider an example. For instance, suppose you ask me, "Why are you running?" and I say, "To help my heart get stronger," to which you reply, "Why do you want to make your heart stronger?" If my answer is, "For the sake of my health, that I might live and live to the full," then this is a "question-stopper;" you can immediately see why I might want to do this, and thus health is a reason for acting that makes my action immediately intelligible; it immediately "make sense." This is because acting for the sake of someone's health is intrinsically valuable and worth doing.
This is the first part of NNL: There is a set of basic goods, as defined above.
- (2) A set of principles of practical reasonableness--these are principles or rules that tell us how it is reasonable to respond to instances of the basic goods. Examples include the golden rule, the prohibition against directly intending to harm a basic good for the sake of something else, rules against arbitrarily discriminating against the goods of certain people, the rule of being reasonably efficient in how one pursues one's plans, etc.
Much more needs to be said here obviously. Many books have been written. However, I don't need to get too much into the details of this for the sake of my post here. That's just the basic idea.
Now, one of the ideas about the basic goods that motivates some of the principles of practical reasonableness is the incommensurability thesis. Here is the thesis of incommensurability:
- (INC) For each basic good x, it is not the case that x offers all the goodness ("to-be-pursuedness") of some other basic good and more.
Now, the motivation for the incommensurability thesis, as I've stated it, is that it seems that each good is beneficial to humans in a way which none of the other goods is. It has a unique type of goodness. Health is good for us in a way that knowledge is not, which is good for us in a way that friendship is not, and so on. If on the other hand we supposed the contrary of incommensurability, then some basic good x would offer all the goodness and more of some other basic good, say y. But then it's hard to see how y could make one's action immediately intelligible (which is part of the definition of a basic good). After all, if someone says, "I did this action for the sake of y," then in some circumstances you can reasonably say, "Well, you should have acted for the sake of x instead, since it offers all the goodness and more of y. So why didn't you?" In which case y would not be a basic good, since acting for the sake of y should make one's action immediately intelligible, and in this case it doesn't. But that's a contradiction, since we assumed y is a basic good. So the incommensurability thesis is true.
Now, one objection is that it seems we should be able to prioritize the goods. Religion is more important than life, life is more important than knowledge, knowledge is more important than fun, and so on. This seems plausible to some. But, if NNL is right, none of these can be "weighed" against the others, since none of them offers all the goodness of any of the others and more. So, the objection goes, if incommensurability holds, then we can't prioritize the goods.
Now, as far as prioritization of goods, that can mean a number of things. If on the one hand talk of prioritization means that some (basic) goods are intrinsically better than others, then it seems this surely must contradict the incommensurability thesis. (Though even here I'm not sure; maybe there's a standard of "better than" which is not based upon having all the goodness and more of another? I don't know.)
If, however, it means that there is no correct way to choose at any given moment between different instances of basic goods, that certainly is not true, and it doesn't follow from incommensurability.
For instance, consider the classic case where I am playing chess and a child is drowning outside. If life and play are incommensurable basic goods, then it seems NNL is committed to saying I can permissibly keep playing chess even though there's a child drowning right outside my window.
The NNL response is to respond that to keep playing chess would be unreasonable not because the good of life is commensurable and greater than the good of play, but rather because I would violate some principle of practical reasonableness which dictates I rationally should save the child.
One way to do this, in terms of grave harms and minor goods, has been suggested by my friend Michael Skiles. I should note that the solution hasn't been formulated by other NNL theorists this way, but it seems a reasonable way to go, and I don't see anything in it that contradicts anything else NNL theorists have said.
Skiles suggests that the principle of reasonableness in play would be that choosing some goods over others might cause or allow grave harm to other people, and it'd be unreasonable for that reason to choose the good that leads to grave harm (since it's unreasonable to allow grave harm to others by one's choice of a minor good, when not choosing that good would have easily prevented such grave harm). By grave harm is meant harm such that it would prevent someone from living a reasonably fulfilled life. Harms can of course be more or less grave by this definition. So, in this case, I'd be allowing a grave harm to the child even though I could have easily prevented this by giving up a minor good (the playing of chess). Thus, I am being unreasonable if I do not get up and save the child, and thus I rationally ought to save the child.
Now, you might think that what I've just said contradicts the incommensurability thesis. After all, I'm now saying that instances of basic goods can be classified as "minor and great," and also that we can speak of "grave harm and minor harm." The problem with this objection is that, again, incommensurability, as defined by NNL, doesn't in itself say that there is no sense in which we can prioritize the goods. On the contrary, it would be very unreasonable to choose a game of chess over saving a kid outside from drowning! It's just that NNL would account for this by appealing to principles of practical reasonableness, such as the one I cited, and not by appealing to the idea that some basic goods offer all the goodness and more of the other. I will call the principle of practical reasonableness that gets us this result (HARM):
- (HARM) It is unreasonable to allow grave harm to others by one's choice of a minor good, when not choosing that good would have easily prevented such grave harm."
- (GG) An instance of a basic good counts as a grave good for a person if the having of that good would determine whether that person lives a reasonably fulfilled life.
- (MG) An instance of a basic good counts as a minor good if it is not a grave good.
- (GH) A harm counts as a grave harm if it is a privation of a grave good.
- (MH) A harm counts as a minor harm if it is not a grave harm.
Now, note that these definitions do not say anything about one good having all the goodness and more of any of the others, so prioritizing based on the "gravity" of the instances of the goods doesn't contradict incommensurability (since, as I said before, all incommensurability says is that none of the basic goods offers all the goodness and more of the others). So, this seems to present us with a legitimate way of getting the right conclusion of the case.
With that said, I want to raise an objection to the objector. Suppose that we modify the case a little bit, so that I'm playing chess against a computer that has the power to destroy all our knowledge and all our sources of knowledge, and will do so if I lose. In fact, why not throw all the beauty in there as well; if I lose, the computer will destroy all our knowledge and vaporize everything that's beautiful in this world. It's not entirely obvious to me that I rationally must stop playing chess to save the child. It will be a tough choice of course, but if we can prioritize the goods by saying life offers all the goodness of knowledge and more then it's not obvious why this would be a tough choice; it would seem to decisively deliver the false conclusion that I must stop playing chess.
Admittedly, we might conclude that even in this case we still rationally ought to save the child. But then I think it would still be because a proper instance of (HARM), along with some other principles of practical reasonableness, will deliver this verdict. And we still have to account for the intuition that it is no longer as obvious that we must do this. If the basic goods are incommensurable, then we can still at least account for the non-obviousness of our obligation to save the child. If they are commensurable, it's not clear how to account for this.
So, in sum, it seems that this argument against incommensurability doesn't work, since arguably NNL can account for our intuitions on these cases just as well as (and, actually, even better than!) people who deny it.
One final worry I'd like to mention: You might think that NNL solves the issue by arbitrarily positing principles of practical reasonableness that deliver the right verdicts. I would reply that first off, they are not arbitrarily posited, but argued for based on the nature of the basic goods and on the nature of rationality. See the work of Finnis, Grisez, Boyle, George, Tollefsen, Rhonheimer, and Murphy, among others. Second, though intuitions might guide the precise formulation of principles, they ultimately are argued for and shown to hold for independent reasons. Finally, if any moral oughts are also rational oughts, i.e. it is sometimes irrational to not do what is morally obligatory, then everyone must have some principles of practical reasonableness that connect the two. For instance, on the view I've been attacking, it seems the relevant principle would be something like this:
- (COMM): It is unreasonable to choose an instance of a basic good x over a basic good y if y offers all the goodness and more of x.
Everybody must choose some principles of practical reasonableness. One thing that distinguishes NNL from other views is which ones they choose, and I think this is what makes NNL so powerful a system.