=25.= 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 a 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.