The most important developments in axiology took place at the end of the nineteenth century and the beginning of the twentieth, with Brentano, Husserl, and Scheler, who may reasonably be considered the three founders of the discipline. In the end, however, all three devoted themselves to tasks other than the development of an axiology as such.

Husserl, and Brentano to a lesser extent, were primarily concerned with developing a formal axiology—Brentano confined himself to uncovering formal axiological axioms (projects we will examine in more detail later).
Scheler, for his part, worked hard to distinguish value from related concepts (such as good and purpose), but probably did not go far enough in drawing this distinction, since for him the discipline whose proper subject is values is not axiology but a 'material ethics of values'. He uses the term 'axiological sphere', but very rarely 'axiology'. One might say that Scheler recognises the 'axiological' as a concept, but not 'axiology' as a discipline.

A characteristic of later authors in whose work we encounter the term 'axiology' is to use it in passing, without definition or sustained analysis, as though no such need had arisen. Thus Delesalle, in a book devoted entirely to values, manages to use the term 'axiology' on only four occasions (for example: Nothing precedes or justifies axiological consciousness, nor does anything guide it; value is therefore the same thing as the movement of consciousness which evaluates ¹), and in each instance we look in vain for a definition or even a brief description of the discipline whose name he employs.

In the landscape of contemporary knowledge, axiology appears to be a stillborn discipline—one with a name but no content, occasionally encountered in passing in the pages of a book, without anyone quite knowing what it refers to.
The reason is straightforward: when the concepts of value and good are conflated, a second confusion follows logically—that of the disciplines which take these two concepts as their respective objects of study. The discipline that studies the good (ethics) becomes confused with the discipline that studies value (axiology). It is then assumed that the problem of values is an ethical problem, and that axiological questions are to be resolved through moral concepts. The first consequence of the oblivion of value is thus the confusion of ethics and axiology; or rather, the former has smothered the latter, preventing it from developing as an autonomous science with its own concepts, its own method, and a coherent content.

Here, then, is the root cause of axiology's oblivion: it is the oblivion of its own object—value itself—through its confusion with neighbouring moral concepts.

We will attempt to identify the privileged symptom of this oblivion of the notion of value—its confusion with the concept of 'good'—in the seminal work of one of the major ethical thinkers of the twentieth century: Moore. We will then observe a remarkable phenomenon: value resists its own oblivion and ends up reasserting itself at the very heart of Moore's thought—a body of work initially grounded entirely in the concept of good—coming to occupy a more prominent place than the latter, and doing so without the author's awareness.

3/ The Disappearance, Then Reappearance, of the Concept of Value in Moore's Work

a) The Disappearance of the Concept of Value

Moore's principal concern in the Principia Ethica is to show that the concept of good is a simple notion—that is, one whose meaning is irreducible to that of any other concept. It is therefore impossible, as hedonism attempts to do, to assert that the very meaning of the word 'good' is 'to give pleasure', and thereby to make the concept of good disappear entirely beneath that of pleasure.

Moore's thesis can be approached from several angles. One might say that no other concept can claim to capture the meaning conveyed by the word 'good', or that good has no synonym. This can be expressed in the provocative tautology: good is good.

It can also be understood by distinguishing two types of identity:
- An analytic identity, of the type: a dwarf is a small man (which is always a tautology, since the predicate is contained in the subject: all dwarfs are by definition small men).
- A synthetic identity, such as: this dwarf is rich (which cannot be a tautology, since the predicate is not contained in the subject).
In analytic identity, subject and predicate are interchangeable; this is impossible in the case of synthetic identity.

A further reformulation of Moore's position would be to assert that, in his view, all statements about the good can only be synthetic, never analytic: If I am asked "How good is to be defined?" my answer is that it cannot be defined, and that is all I have to say about it. But disappointing as these answers may appear, they are of the very last importance […] They amount to this: That propositions about the good are all of them synthetic and never analytic ².

Finally, the good may be described as 'unanalysable' and 'indefinable'.

To be definable, the good would have to be analysable—which would require it to be a complex notion. We can, for example, define man as a political animal (zoon politikon), as Aristotle did, because analysis reveals two simpler constituent concepts: animal and rational. But the good is not constituted through the combination of two other concepts; it derives its meaning from itself alone: I say that it is not composed of any parts, which we can substitute for it in our minds when we are thinking of it ³.

We then arrive at a conclusion that seems to encapsulate the central finding of this investigation: There is nothing whatsoever which we could substitute for good; and that is what I mean, when I say that good is indefinable ⁴.

1. Freedom and value
2. G.H. Moore, Principia Ethica, ch.I, §6
3. Ibid, ch.I, §7
4. Ibid, ch.I, §8