Sam Harris’ erroneous dismissal of the is/ought gap


I finally started to read Sam Harris’ The Moral Landscape: How Science Can Determine Human Values to see what all of the controversy was about. I went into to the book with a somewhat negative impression, but I’m keeping an open mind. So far, the book has surprised me a bit. There are some genuine nuggets of good thinking. For example, I found Harris’ critique of moral relativism quite fun. Whether or not it’s a good critique is an entirely different matter (my knowledge of ethics isn’t good enough to tell).

However, many of my fears have already been realized. Sam Harris doesn’t actually show how science can determine human values. He just makes an assumption about utilitarianism and does an exercise in applied ethics. It’s not entirely useless, but it’s not that useful either. He also makes some outright terrible arguments. One example is his rejection of the is/ought distinction put forward by David Hume. Here’s the passage of interest:

Many moral skeptics piously cite Hume’s is/ought distinction as though it were well known to be the last word on the subject of morality until the end of the world. They insist that notions of what we ought to do or value can be justified only in terms of other “oughts,” never in terms of facts about the way the world is. After all, in a world of physics and chemistry, how could things like moral obligations or values really exist? How could it be objectively true, for instance, that we ought to be kind to children?

But this notion of “ought” is an artificial and needlessly confusing way to think about moral choice. In fact, it seems to be another dismal product of Abrahamic religion—which, strangely enough, now constrains the thinking of even atheists. If this notion of “ought” means anything we can possibly care about, it must translate into a concern about the actual or potential experience of conscious beings (either in this life or in some other). For instance, to say that we ought to treat children with kindness seems identical to saying that everyone will tend to be better off if we do. The person who claims that he does not want to be better off is either wrong about what he does, in fact, want (i.e., he doesn’t know what he’s missing), or he is lying, or he is not making sense. The person who insists that he is committed to treating children with kindness for reasons that have nothing to do with anyone’s well being is also not making sense.

I think Harris is correct to suggest that people who say that we can never derive an ought from an is are wrong. Hume never said that in his original essay and just because there’s a gap between is statements and ought statements doesn’t mean we can never bridge it. The problem is that Harris never shows us how to get there. He merely says that any notion of “ought” should be about the well-being of conscious creatures.

Take his example. Harris is trying to say that:

1. Treating children with kindness makes them happy

2. Therefore, we ought to treat children with kindness

But these are two completely different kinds of claims and it’s not immediately obvious that 1 necessarily implies 2. It only becomes obvious when you assume that we ought to maximize the well-being of conscious creatures. So all Harris ends up actually saying is:

1. Treating children with kindness makes them happy, increasing their well-being

2. We ought to maximize the well-being of conscious creatures

3. Therefore, we ought to treat children with kindness

So how does Harris get away with sneaking in an unscientific prior? He simply claims that everyone does this:

We must smuggle in an “unscientific prior” to justify any branch of science. If this isn’t a problem for physics, why should it be a problem of a science of morality? Can we prove, without recourse to any prior assumptions, that our definition of “physics” is the right one? No, because our standards of proof will be built into any definition we provide. We might observe that standard physics is better at predicting the behavior of matter than Voodoo “physics” is, but what could we say to a “physicist” whose only goal is to appease the spiritual hunger of his dead ancestors? Here, we seem to reach an impasse. And yet, no one thinks that the failure of standard physics to silence all possible dissent has any significance whatsoever; why should we demand more of a science of morality?

This argument reminds me of a problem in philosophy of science known as theory-laden observations. This is when the observations made by an investigator are influenced by some theoretical model he/she is using. I’ve talked about the Prout Hypothesis and how it lead to incorrect observations regarding molecular weights. There are dozens of more examples. However, while our observations might be informed by some theoretical apparatus, they are not determined by it:

Another point that serves to get the “theory-dependence of experiment” in perspective is that, however informed by theory an experiment is, there is a strong sense in which the results of an experiment are determined by the world and not by the theories. Once the apparatus is set up, the circuits completed, the switches thrown and so on, there will or will not be a flash on the screen, the beam mayor may not be deflected, the reading on the ammeter mayor may not increase. We cannot make the outcomes conform to our theories. (Chalmers 1999: 39-40)

Even though a physicist (or any field of science) makes prior assumptions before he studies the workings of the universe, these assumptions are ultimately constrained by observation and subject to change. As our tools of observation improve, our theories about the universe will change and the definition of physics will change. Unlike science, ethics doesn’t benefit as much from observation. No doubt, as Harris claims, that as our understanding of brain states advances, we can improve the well being of conscious creatures and “improve” our understanding of ethics. But this only works if we assume that morality is about maximizing the well-being of conscious creatures. How can observation change our initial ethical assumption? Is that even possible? This seems like a big difference between science and ethics, a difference that Harris conveniently overlooks. Moreover, many, if not all, of these assumptions are agreed upon by physicists before analysis is undertaken. For example, almost all physicists will agree on the definition of an atom. That is evidently not the case for terms like “morally good” and “morally bad”.  And Harris doesn’t really provide a good reason why we should choose “well being” as the set definition for morally good as opposed to many other definitions put forward by other moral theories. This doesn’t even touch upon the problems with Harris’ moral theory, utilitarianism, but I’ll leave that to the experts.

To be fair to Harris, I haven’t finished his book yet, so my judging could be premature. But I have my doubts. If he did address these important questions, there wouldn’t be dozens of critical reviews of his book. If he did make a real contribution to moral theory, his book wouldn’t be receiving so much scorn from important academic circles. Either way, it’s still a fun read. The writing is provocative and it’s worth taking a look at. Nevertheless, given the main goal Harris set out to make, the book is a complete failure.


The Methodenstreit and Myth of the Scientific Method

Book review: Sam Harris’ The Moral Landscape by Russell Blackford

You Can’t Derive Ought from Is by Sean Carroll

About Sam Harris’ claim that science can answer moral questions by Massimo Pigliucci

Sam Harris is wrong about science and morality by Brian Earp

The Facts Fetish by Thomas Nagel

Sam Harris – The Moral Landscape (review) by Luke Muehlhauser

Sam Harris vs. Sean Carroll on Science and Morality by Luke Muehlhauser

Toward a Science of Morality by Sam Harris


1. Chalmers, A. F. What Is This Thing Called Science? Indianapolis: Hackett Pub., 1999. Print.

2. Harris, Sam. The Moral Landscape: How Science Can Determine Human Values. New York: Free, 2010. Print.



Filed under Home, Philosophy

2 responses to “Sam Harris’ erroneous dismissal of the is/ought gap

  1. I agree with your criticisms, especially in your first half here. Oversimplification creeps in. Is and Ought are more complicated than this. One criticism I read somewhere about Harris that sticks in my mind is that using well-being as a moral benchmark can easily run into problems with other important criteria, such as justice–a criminal’s family may be unhappy if the criminal goes to jail, but in the long run…. Similarly, most parents would dread the thought that whatever makes a child happy should trump all other considerations. I wrote about the book here:

    • Thanks for the comment. In the child example he would probably respond with some like “suffering is sometimes good”. As he says in the introduction, “it seems clear that ascending the slopes of the moral landscape may sometimes require suffering.” However, Utilitarianism leads to a bunch of measurement problems that Harris doesn’t address. Your first example was a good example of one. He just says that someday science will probably have an answer for them.

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