Right and welfare are limited. But duty claims to hold without condition. So I cannot simply take its content from right and welfare. What then remains for duty?

Only the empty form. Duty says: Do your duty. But it does not say what.

What did Kant achieve?

Kant showed that the root of duty is the free self-determination of the will. That was a great gain. Only since then has the theory of the will had firm ground.

Where is the weakness?

Someone who stops at this duty ends up in empty talk. Kant’s test runs like this: Can my rule become a law for all? Can I will it without contradicting myself?

But contradiction alone says nothing. An example: It is no contradiction that there is no property at all. A contradiction arises only once we already assume: property ought to exist. Then theft is a contradiction. But the “property ought to exist” does not come from the test. It must already be there beforehand.

So the test cannot produce any duties. It only checks what we already presuppose. On the contrary: it can justify any wrongful action.

Summary: Kant grounded duty in freedom. That is a great merit. But mere duty stays empty and cannot bring forth any content.

The Spirit of Christianity and Its Fate: Jesus’ attitude to the moral commandments – Hegel’s early critique of the mere “ought”

The Life of Jesus (1795) – Jesus as a teacher of Kantian morality

If the determinacy of property in general is posited, then the tautological proposition can be made from it: property is property and nothing else; this tautological production is the legislating done by this practical reason: property, if property exists, must be property; but if the opposed determinacy — the negation of property — is posited, then the legislating of that very same practical reason yields the tautology: non-property is non-property; if there is no property, then that which would be property must be sublated. But it is precisely what is at issue to demonstrate that property must exist; the whole matter turns solely on that which lies outside the capacity of this practical legislating of pure reason.

A maxim that, on this principle, is immoral because it contradicts itself, is, precisely because it expresses the sublation of a determinacy, absolutely rational, and therefore absolutely moral; for the rational, on its negative side, is the indifference of determinacies, the being-sublated of the conditioned. Thus the determinacy of helping the poor expresses the sublation of the determinacy that is poverty; the maxim whose content is that determinacy, when tested by raising it to the principle of a universal legislation, will prove to be false, for it annihilates itself. If it is thought that the poor are universally helped, then either there are no longer any poor at all, or else there is nothing but poor people, in which case none remain who could help; and so in both cases help would drop away; the maxim, thought as universal, thus sublates itself.