Moore's substitution is taken for granted. It takes place, without asserting itself, in silence, an unnoticed ellipsis, from its very author, who asserts a few lines later that nothing can take the place of "good". But this silence actually contains many things. It is an evocative silence. This ellipse, which as such is akin to a region of non-being, is charged, in all its emptiness, with all the authority of the past.

What we see here is a twofold disappearance of the concept of value.

Firstly, 'value' disappears as an inconsistent concept, since there is an analytical identity between good and value. Value is merely a synonym for the word good (and has as its content only that of the word "good"; it is an empty shell). "Value" would retain all the dignity of a consistent concept if at least a synthetic identity were affirmed with the concept "good", which is not the case.

But above all, "value" itself disappears as a synonym, since Moore keeps repeating that nothing can be substituted for "good" (in direct contradiction with the substitution he himself has just made). If all we can say is that "good is good", we are not even allowed to assert that "good is value", even in the tautological sense.
In other words, the concept of value still had the 'dignity' of a synonym, an empty shell. Now it has been stripped of its dignity. "Value' is no longer even a synonym, it is a shadow, a word that disappears as soon as it is uttered, the equivalent in moral philosophy of what the point is in mathematics: something that has no length, width or thickness, that is nothingness rather than being.

Moore's book is therefore fascinating in that it condenses and sums up this phenomenon at work in the history of moral philosophy: the disappearance of the concept of 'value' in favour of the concept of 'good'.

2) The confusion of good/ value/ price/ duty/ existence

The passage we have just studied is not the only one in which this confusion occurs. In fact, Moore continues - despite his intention - to give synonyms to the word "good". For example: Whenever he thinks of intrinsic value, or intrinsic worth, or says that a thing ought to exist, he has before his mind the unique object—the unique property of things—that I mean by good ¹.

No less than four concepts are now analytically identified with the good: price, value, duty, existence (or, if we prefer, "ought to exist"). "Ought to" refers to a "duty" or "moral obligation".
In other words, to be good is to have a price, to have a value, or to have the duty to exist.
These three or four concepts, as synonyms of the good, are therefore synonymous with each other: they have the same meaning.

Nevertheless, to say that to have value is to have a duty to exist mixes two errors: the confusion of value and duty, and a dogmatic (unfounded) judgement that only what exists can have value, to which we can oppose the axiological judgement which consists of affirming that only what is dreamt of, the ideal, or artificial paradises, has value.

1. Ibid., chap.1, §13