<The following is a portion of Larrys Text, wikification is encouraged. This notice will be removed when it is wikified...>
Naturalism, sometimes also called definism, holds that ethical terms can be defined; the meaning of ethical sentences can be given in totally non-ethical terms. So to question (1), "Can the meaning of ethical sentences be restated in other words that do not use normative concepts like ?good? and ?right??" the naturalist answers, "Definitely." Why? Because ultimately, goodness and right are natural properties; they are ultimately properties of things that can be located in the natural world. So then here?s a definition of "naturalism":
Naturalism is the view that ethical sentences express propositions, and that they can be reduced to nonethical sentences.
Notice that this definition has two parts, the part that comes before the "and" and the part that comes after the "and." Let?s take a closer look at each part.
First, there?s the notion that ethical sentences express propositions. Well, what exactly does that mean? I?ve already told you what propositions are; they are, roughly, what meaningful sentences are supposed to be about. So if an ethical sentence does express a proposition, then there is indeed something that the sentence is about. It?s not like the claim, "Mary is a good person," is about nothing. It?s about Mary, and it?s identifying her goodness.
To get a better idea of what it means to express a proposition, compare this to something that doesn?t express a proposition. Say I?m minding a convenience store, and I see a thief pick up a candy bar and run. I just manage to exclaim, "Hey!" When I say, "Hey!" I?m not expressing a proposition. I?m not saying, "That?s a thief there"; I?m not saying, "that thief is getting away"; I?m not saying, "that thief really annoys me." I?m not saying anything at all, really. And that?s the point: it?s not a proposition that I?m expressing. Rather, it?s an emotional state that I?m expressing. I am surprised and angered and I express my surprise and anger to the thief by saying "Hey!"
So what the first part of the definition of "naturalism" says is that ethical sentences do express propositions. They aren?t just emotional outbursts, as though I were saying, "Hey!" or "Yay for Mary!" They are actually expressing propositions that can be true or false. And derivatively, you can say that ethical sentences themselves are either true or false.
That?s another important way to explain what it means for ethical sentences to express propositions; if they express propositions, they?re either true or false. So if you?re a naturalist then you think ethical sentences are either true or false. So for example, it can be true or false that Mary is a good person. It can be true or false that stealing and lying are always wrong. On the other hand, if you think the sentence, "Mary is a good person" can?t be either true or false -- if you say that, then you?re not a naturalist. To be a naturalist, you have to think that ethical sentences are either true or false.
And notice, if I say that ethical sentences merely express emotions, as though they they were just exclamations like "Hey!" and "Yay for Mary!" then I don?t think ethical sentences are true or false. Consider this: "It?s true that ?Hey!?" Or this: "It?s false that ?Yay for Mary!?" Well that doesn?t make any sense. Mere expressions of emotion, mere outbursts, aren?t true or false. They can be appropriate or inappropriate. If Mary happens to be an ax murderess, then it?s totally inappropriate for me to say, "Yay for Mary!" But it?s not false to say that, because mere emotional expressions aren?t true or false: only sentences that express propositions can be true or false.
OK, this has been all by way of getting you to understand the first part of the definition of "naturalism," and that part reads, "the view that ethical sentences express propositions." Let?s give that view a name: call it cognitivism. So cognitivism will be the view that ethical sentences express propositions. Having explained this view, it?s going to make it easier later on to understand so-called noncognitivism, because noncognitivism specifically denies this view.
But now what about the second part of the definition of "naturalism"? The second part says that ethical sentences "can be reduced to nonethical sentences." Now you?re going to have to remember this notion of reduction from our discussion of the mind-body problem. I told you that philosophy is interconnected and interdependent -- well, it really is! Anyway, so what does it mean to say that ethical sentences can be reduced to nonethical sentences? It just means that you can state the meaning of ethical sentences in other words, in sentences that don?t include any ethical terms like "good" and "right." All this talk of good and bad, right and wrong, moral and immoral, and so forth -- that?s all just shorthand for some complex propositions about what human beings need, or desire, or what gives them pleasure, or what secures their long-term happiness, and so forth. So this notion that ethical sentences can be reduced to nonethical sentences really amounts to saying that ethical sentences are a kind of shorthand, a kind of very useful abbreviation, for claims about nonethical facts about human needs, desires, and so forth.
Now, when we discuss the theory of value, I?m going to give you some theories of what "good" means. So I?ll be giving you a few examples of how you could reduce talk of goodness to talk about other things -- like pleasure, or happiness. So really you could look at the theory of value as a way of thinking naturalism through; the theory of value can be regarded as an attempt to figure out how to reduce goodness to nonethical properties; and for that matter, the theory of conduct, as we?ll see, can be regarded as an attempt to figure out how to reduce moral obligations and permissions to nonethical properties as well. So if you are wondering how on earth we could ever reduce ethical sentences to nonethical sentences, just wait, because we?ll be looking at some examples of such reductions.