A.

    § 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’: …
    § 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. …
    § 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. …