Husserl was highly interested by these axioms and developed, in Lectures on ethics and value theory, the project of a formal axiology as such. He went a step further than Brentano, who confined himself to the proposition of axioms.

Husserl assumes that an analogy could be made between the theoretical (or judicative) reason, and the practical reason. If we draw a parallel between logic and ethics, and the types of reason with which these disciplines are concerned, (namely, judicative or practical reason), we see that To the logic, in the strict sense of a formal logic, a formal practice must correspond, which is a priori in a similar way ¹.
But the sphere of praxis includes for Husserl both Ethics and evaluation, in the broad sense. This leads to the idea of a formal axiology as a formal a priori discipline of values, of contents of values and meanings of values – a discipline which, for some fundamental reasons, is closely linked to the formal practice ².

In order to verify whether there is a real analogy between the two spheres, both theoretical and practical, we must try to find formal ethical and axiological laws.

So the point is to formalize axiology, in others words, make abstraction of any material determination of values, empty the content and consider only the form-value, the vacuum of the value in general ³ as D. Pradelle says.

One of the results of this investigation is that, according to Husserl, the principle of excluded middle (either a door is open, or it is closed; A or not-A, there is no third possibility) is not found in axiology. Instead of it, we find the principle of excluded fourth: either something has a positive value, or it has a negative one, or it has no value at all: in the axiological sphere, there are three fundamental modalities of value – the positive value, the negative value and the null value (adiaphoron) ⁴.
In this way, Husserl proposes a number of formal axiological laws, often inspired by Brentano’s ones. For example: a pure good has more value than a good mixed with an evil. But I must examine the general project of formal axiology, rather than the particular results of this investigation.

1. Lectures on ethics and value theory, Section 1, §1
2. Ibid.
3. Ibid, préface
4. Ibid.