After 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 acknowledge Husserl in this work, giving rise to a somewhat strained correspondence, as Husserl felt his ideas had been appropriated.

Lessing identifies several axiological axioms modelled on mathematical principles.
He begins by distinguishing 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.

He then sets out the addition axioms:
(value a + value b) > value a
(value a - value b) < value a

To these may be added:
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 gives rise to Lessing's three axioms of dependence, among them: '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.

Here again, these axiological axioms are logical or mathematical laws applied to values. A genuinely objective science of values can thus be built upon them, with objectivity secured by avoiding any reliance on unfounded value judgements.
These axioms establish the formal rules that value judgements must follow if they are to be employed in reasoning, but they say nothing about the specific content of those judgements. We know from these axioms, for instance, 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.