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. 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.