It results from the conclusions of Chapter I, that all ethical questions fall under one or other of three classes. The first class contains but one question—the question What is the nature of that peculiar predicate, the relation of which to other things constitutes the object of all other ethical investigations? or, in other words, What is meant by good? This first question I have already attempted to answer. The peculiar predicate, by reference to which the sphere of Ethics must be defined, is simple, unanalysable, indefinable. There remain two classes questions with regard to the relation of this predicate to other things. We may ask either (1) To what things and in what degree does this predicate directly attach? What things are good in themselves? or (2) By what means shall we be able to make what exist in the world as good as possible? What causal relations hold between what is best in itself and other causal relations hold between what is best in itself and other things? (§ 24 ¶ 1)

In this and the two following chapters, I propose to discuss certain theories, which offer us an answer to the question What is good in itself? I say advisedly—an answer: for these theories are all characterised by the fact that, if true, they would simplify the study of Ethics very much. They all hold that there is only one kind of fact, of which the existence has any value at all. But they all also possess another characteristic, which is my reason for grouping them together and treating them first: namely that the main reason why the single kind of fact they name has been held to define the sole good, is that it has been held to define what is meant by good itself. In other words they are all theories of the end or ideal, the adoption of which has been chiefly caused by the commission of what I have called the naturalistic fallacy: they all confuse the first and second of the three possible questions which Ethics can ask. It is, indeed, this fact which explains their contention that only a single kind of thing is good. That a thing should be good, it has been thought, means that it possesses this single property: and hence (it is thought) only what possesses this property is good. The inference seems very natural; and yet what is meant by it is self-contradictory. For those who make it fail to perceive that their conclusion what possesses this property is good is a significant proposition: that it does not mean either what possesses this property, possesses this property or the word good denotes that a thing possesses this property. And yet, if it does not mean one or other of these two things, the inference contradicts its own premise. (§ 24 ¶ 2)

I propose, therefore, to discuss certain theories of what is good in itself, which are based on the naturalistic fallacy, in the sense that the commission of this fallacy has been the main cause of their wide acceptance. The discussion will be designed both (1) further to illustrate the fact that the naturalistic fallacy is a fallacy, or, in other words, that we are all aware of a certain simple quality, which (and not anything else) is what we mainly mean by the term good; and (2) to shew that not one, but many different things, possess this property. For I cannot hope to recommend the doctrine that things which are good do not owe their goodness to their common possession of any other property, without a criticism of the main doctrines, opposed to this, whose power to recommend themselves is proved by their wide prevalence. (§ 24 ¶ 3)

The theories I propose to discuss may be conveniently divided into two groups. The naturalistic fallacy always implies that when we think This is good, what we are thinking is that the thing in question bears a definite relation to some one other thing. But this one thing, by reference to which good is defined may be either what I may call a natural object—something of which the existence is admittedly an object of experience—or else it may be an object which is only inferred to exist in a supersensible real world. These two types of ethical theory I propose to treat separately. Theories of the second type may conveniently be called metaphysical, and I shall postpone consideration of them till Chapter IV. In this and the following chapter, on the other hand, I shall deal with theories which owe their prevalence to the supposition that good can be defined by reference to a natural object; and these are what I mean by the name, which gives the title to this chapter, Naturalistic Ethics. It should be observed that the fallacy, by reference to which I define Metaphysical Ethics, is the same in kind; and I give it but one name, the naturalistic fallacy. But when we regard the ethical theories recommended by this fallacy, it seems convenient to distinguish those which consider goodness to consist in relation to something which exists here and now, from those which do not. According to the former, Ethics is an empirical or positive science: its conclusions could be all established by means of empirical observation and induction. But this is not the case with Metaphysical Ethics. There is, therefore, a marked distinction between these two groups of ethical theories based on the same fallacy. And within Naturalistic theories, too, a convenient division may also be made. There is one natural object, namely pleasure, which has perhaps been as frequently held to be the sole good as all the rest put together. And there is, moreover, a further reason for treating Hedonism separately. That doctrine has, I think, as plainly as any other, owed its prevalence to the naturalistic fallacy; but it has had a singular fate in that the writer, who first clearly exposed the fallacy of the naturalistic arguments by which it had been attempted to prove that pleasure was the sole good, has maintained that nevertheless it is the sole good. I propose, therefore, to divide my discussion of Hedonism from that of other Naturalistic theories; treating of Naturalistic Ethics in general in this chapter, and of Hedonism, in particular, in the next. (§ 25 ¶ 1)

The subject of the present chapter is, then, ethical theories which declare that no intrinsic value is to be found except in the possession of some one natural property, other than pleasure; and which declare this because it is supposed that to be good means to possess the property in question. Such theories I call Naturalistic. I have thus appropriated the name Naturalism to a particular method of approaching Ethics—a method which, strictly understood, is inconsistent with the possibility of any Ethics whatsoever. This method consists in substituting for good some one property of a natural object or of a collection of natural objects; and in thus replacing Ethics by some one of the natural sciences. In general the science thus substituted is one of the sciences specially concerned with man, owing to the general mistake (for such I hold it to be) of regarding the matter of Ethics as confined to human conduct. In general, Psychology has been the science substituted, as by J.S. Mill; or Sociology, as by Professor Clifford, and other modern writers. But any other science might equally well be substituted. It is the same fallacy which is implied, when Professor Tyndall recommends us to conform to the laws of matter: and here the science which is proposed to substitute for Ethics is simply Physics. The name then is perfectly general; for, no matter what the something is that good is held to mean, the theory is still Naturalism. Whether good be defined as yellow or green or blue, as loud or soft, as round or square, as sweet or bitter, as productive of life or productive of pleasure, as willed or desired or felt: whichever of these or of any other object in the world, good may be held to mean, the theory, which holds it to mean them, will be a naturalistic theory. I have called such theories naturalistic because all of these terms denote properties, simple or complex, of some simple or complex natural object; and, before I proceed to consider them, it will be well to define what is meant by nature and by natural objects. (§ 26 ¶ 1)

By nature, then, I do mean and have meant that which is the subject-matter of the natural sciences and also of psychology. It may be said to include all that has existed, does exist, or will exist in time. If we consider whether any object is of such a nature that it may be said to exist now, to have existed, or to be about to exist, then we may know that that object is a natural object, and that nothing, of which this is not true, is a natural object. Thus, for instance, of our minds we should say that they did exist yesterday, that they do exist to-day, and probably will exist in a minute or two. We shall say that we had thoughts yesterday, which have ceased to exist now, although their effects may remain: and in so far as those thoughts did exist, they too are natural objects. (§ 26 ¶ 2)

There is, indeed, no difficulty about the objects themselves, in the sense in which I have just used the term. It is easy to say which of them are natural, and which (if any) are not natural. But when we begin to consider the properties of objects, then I fear the problem is more difficult. Which among the properties of natural objects are natural properties, and which are not? For I do not deny that good is a property of certain natural objects: certain of them, I think, are good; and yet I have said that good itself is not a natural property. Well, my test for these too also concerns their existence in time. Can we imagine good as existing by itself in time, and not merely as a property of some natural object? For myself, I cannot so imagine it, whereas with the greater number of properties of objects—those which I call the natural properties—their existence does seem to me to be independent of the existence of those objects. They are, in fact, rather parts of which the object is made up than mere predicates which attach to it. If they were all taken away, no object would be left, not even a bare substance: for they are in themselves substantial and give to the object all the substance that it has. But this is not so with good. If indeed good were a feeling, as some would have us believe, then it would exist in time. But that is why to call it so is to commit the naturalistic fallacy. It will always remain pertinent to ask, whether the feeling itself is good; and if so, then good cannot itself be identical with any feeling. (§ 26 ¶ 3)