=66.= The term ‘metaphysical’ is defined as having reference primarily to any object of knowledge which is not a part of Nature--does not exist in time, as an object of perception; but since metaphysicians, not content with pointing out the truth about such entities, have always supposed that what does not exist in Nature, must, at least, _exist_, the term also has reference to a supposed ‘supersensible reality’: 110 =67.= and by ‘metaphysical Ethics’ I mean those systems which maintain or imply that the answer to the question ‘What is good?’ _logically depends_ upon the answer to the question ‘What is the nature of supersensible reality?.’ All such systems obviously involve the same fallacy--the ‘naturalistic fallacy’--by the use of which Naturalism was also defined. 113 =68.= Metaphysics, as dealing with a ‘supersensible reality,’ may have a bearing upon _practical_ Ethics (1) if its supersensible reality is conceived as something future, which our actions can affect; and (2) since it will prove that _every_ proposition of practical Ethics is false, if it can shew that an eternal reality is either the only real thing or the only good thing. Most metaphysical writers, believing in a reality of the latter kind, do thus imply the complete falsehood of every practical proposition, although they fail to see that their Metaphysics thus contradicts their Ethics. 115 B. =69.= But the theory, by which I have defined Metaphysical Ethics, is _not_ that Metaphysics has a logical bearing upon the question involved in _practical_ Ethics ‘What effects will my action produce?,’ but that it has such a bearing upon the fundamental ethical question ‘What is good in itself?.’ This theory has been refuted by the proof, in Chap. I, that the naturalistic fallacy is a fallacy: it only remains to discuss certain confusions which seem to have lent it plausibility. 118 =70.= One such source of confusion seems to lie in the failure to distinguish between the proposition ‘This is good,’ when it means ‘This _existing_ thing is good,’ and the same proposition, when it means ‘The existence of this _kind_ of thing would be good’; 118 =71.= and another seems to lie in the failure to distinguish between that which _suggests_ a truth, or is a _cause_ of our knowing it, and that upon which it _logically_ depends, or which is a _reason_ for believing it: in the former sense fiction has a more important bearing upon Ethics than Metaphysics can have. 121 C. =72.= But a more important source of confusion seems to lie in the supposition that ‘to be good’ is _identical_ with the possession of some supersensible property, which is also involved in the definition of ‘reality.’ 122