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CAN ONE DERIVE AN “OUGHT” FROM AN “IS”?

11/18/2015

2 Comments

 
As mentioned in a recent post, many religious believers claim that without God there can be no objective right or wrong. This creates an understandable temptation among atheists to find an alternative basis for objective morality. And because atheists usually look for this alternative in science, they often begin by rejecting the well-known principle that one cannot derive an “ought” from an “is.”

One such atheist is Richard Carrier. He maintains that this principle is “not merely illogical, it's demonstrably false. We get an 'ought' from an 'is' all the time.”

Carrier's basic argument is that there are objective facts about what people desire, as well as objective facts about how to achieve these desires, and that “wherever both are an empirically demonstrated fact, the imperative they entail is [also] an empirically demonstrated fact.” So, for instance, consider the following example:

1. You want your car to run well
2. In order for your car to run well, its oil must be changed with sufficient regularity

3. Therefore, you ought to change your car's oil with sufficient regularity

Here, we have two “is” premises which (we can assume) state empirical facts, and an “ought” conclusion. And since the conclusion is supposedly derived from factual statements, Carrier believes it is “factually true independent of human opinion or belief.” He thinks he has solved the problem and that therefore the principle that one cannot derive an “ought” from an “is” should “never be uttered again.”

Well, sorry, but I'm going to utter it once again: One cannot derive an “ought” from an “is,” and it isn't hard to understand why. In deductive arguments, there cannot be anything in the conclusion that isn't already contained in the premises: All deduction does is “extract” some of the information included in the premises; it cannot add anything new. It follows that if the premises of a valid argument contain no “oughts,” then the conclusion cannot contain any “oughts” either (except in a trivial sense which is discussed in the note below).

And in fact it's easy to see what's wrong with Carrier's argument. That “you ought to change your car's oil with sufficient regularity” only follows if it is also the case that you ought to want your car to run well. In other words, there must already be an “ought” in the premises if the conclusion is to follow. Compare:

1. Manson wants to kill lots of innocent people
2. In order to kill lots of innocent people, one needs weapons
3. Therefore, Manson ought to get weapons

Is the conclusion here “factually true independent of human opinion or belief”? According to Carrier's argument, it is! But who seriously thinks that it is a moral truth that Manson should acquire weapons?

Nor is it difficult to come up with a counter-example to the first argument. Suppose Mary is an extreme environmentalist and disagrees that we ought to want our cars to run at all. Can we demonstrate to Mary the “fact” that you ought to change your car's oil regularly?

No one has ever successfully bridged the is-ought gap. If you want to maintain that there are objective moral truths, you ought to find some other way.


Note:
For anyone who might be interested, the trivial sense in which one can derive a conclusion that contains “ought” from premises that do not is as follows: Given that from p you can conclude p or q, one can validly argue something like,

1. The earth is round
2. Therefore, the earth is round or you ought to go fly a kite.

But this is irrelevant, as it is not a way to derive moral principles (the conclusion is true, but it does not actually say that you should go fly a kite).


​The quotations are from Richard Carrier, “Moral Facts Naturally Exist (and Science Could Find Them),” in The End of Christianity, ed. John Loftus, pp. 334-335


2 Comments
Tyler
3/18/2021 07:29:02 pm

One could make a distinction between rational oughts and moral oughts. There is nothing wrong with bridging the is-ought gap with respect to rational/hypothetical oughts in every example you gave. If you have a desire to have your car run well, then you ought to give it an oil change. That's just what "ought" means. The objective of those deductive arguments should be just to make explicit what an ought really is. Likewise, moral oughts are just a subset of hypothetical oughts. But moral oughts are special (so Carrier would claim) in that they universally apply to you regardless of your percieved immediate goals and desires. Hence, they are "objective" in this way. The moral ought is a prescription derived from the essential facts of your very being (in Carrier's case, your essential aversion to pain and dissatisfaction). Hume need to be taken to task for confusing moral discourse for hundreds of years, just as Descartes needs to be for separating mind and body as separate substances.

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Franz Kiekeben
11/9/2021 12:44:21 pm

Sorry I didn't reply sooner, but I just saw this (Weebly stopped notifying me of new comments for some reason).

Certainly it is the case that in order for a car to run well, its oil must be changed. This is a fact about reality. And generally speaking it is also the case that you want your car to run well – so let's just assume that is the case. But does it necessarily follow that you OUGHT to change your car's oil? No.

There is no logical contradiction involved in claiming both “you want your car to run well” and “you should not change its oil”. This is not the same as denying that, in order to get what you want in this case, you need to change the oil (if it was, it would be denying a fact about reality). What it is denying is that what you happen to want is what you ought to do.

You add that, according to Carrier, moral oughts are the same for everyone, that they are about avoiding pain and dissatisfaction (and presumably achieving well-being). But first of all, that's just obviously false. That's not what everyone is concerned with all the time, nor is it the only thing that matters for a lot of people (including me) when considering moral issues. Second, and worse, even if it were true, it still wouldn't follow that what everyone wants is what they ought to do (anymore than it follows that what any given individual wants is what he should do). It could be that desires of the human species as a whole are bad. (I'm not claiming this myself. I'm just pointing out that such a claim isn't necessarily false.)

A couple of years ago, I wrote another blog post on Hume's argument, in case you're interested:
www.franzkiekeben.com/blog/ought-and-is-revisited

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