Following Husserl, we come to Th. Lessing. While Husserl’s writings on ethics and formal axiology were somewhat overshadowed by his work on phenomenology, one of his seminar attendees, Th. Lessing, inspired by Husserl’s ideas, pursued a similar project in his Studien zur Wertaxiomatik. Notably, Lessing did not reference Husserl in this work, leading to a somewhat tense correspondence, as Husserl felt his ideas had been appropriated.

Lessing identifies several axiological axioms modeled after mathematical principles.
First, he distinguishes the axioms of constitution:
Identity: 'X value' = 'X value'.
Contradiction: 'value X' has an opposite, 'non-value of X'.
Excluded middle: either 'X' has a value, or it does not.

Next, Lessing outlines the addition axioms:
(value a + value b) > value a
(value a - value b) < value a

To these, we can add:
Commutativity axioms: value a x value b = value b x value a.
Associativity axioms: (value a + value b) + value c = value a + (value b + value c), etc.

This leads to Lessing’s three axioms of dependence, including: 'If the value of a depends on the value of b, then b is of greater value than a', thereby establishing a principle of hierarchy.

Once again, these axiological axioms are logical or mathematical laws applied to values. Thus, a truly objective science of values can be built upon these axioms, with objectivity ensured by avoiding any reliance on unfounded value judgements.
These axioms establish the formal rules that value judgements must follow if they are to be used in reasoning, but they do not address the specific content of these judgements. For instance, we know from these axioms that 'the value of a' multiplied by 'the value of b' equals 'the value of b' multiplied by 'the value of a', yet they tell us nothing about what 'a' or 'b' actually represents—that is, what can possess value.