In brief: Because a contract proceeds from the arbitrary will of the contracting parties and produces a common, not a universal will. Whoever thinks the state as a contract makes membership a matter of pleasure and transfers the rules of private property into a sphere where they do not belong. Hegel directs this objection expressly against Kant as well – and against Kant’s treatment of marriage.
What a contract is
The answer stands already in abstract right, long before the state. § 75 determines contract by three marks: it proceeds from arbitrary will; the will that comes into being through it is only one posited by the parties, and hence „only common, not universal in and for itself“; and its object is „a single external thing“. None of the three fits the state.
Just as little does the nature of the state lie in a contractual relation, whether the state be taken as a contract of all with all, or as a contract of all these with the prince and the government. – The intrusion of this, as well as of the relations of private property in general, into the relation of the state has produced the greatest confusions in constitutional law and in actuality.
Groundlines, § 75 note
The side-blow at Kant
The same paragraph contains one of the book’s harshest judgements on a predecessor. In the Metaphysics of Morals Kant had determined marriage as a contract concerning the reciprocal use of the sexual organs. Hegel:
The concept of contract cannot, therefore, subsume marriage under it; this subsumption is put forward, in its – one must say – disgracefulness, by Kant.
Groundlines, § 75 note
The argument is the same as with the state: a relation in which the participants give up precisely their singularity cannot be described with the categories of the exchange of things. That marriage and the state are disposed of in one sentence is no accident – for Hegel both are shapes of ethical life, not of commerce.
What he concedes to Rousseau – and where he leaves him
In § 258 note Rousseau is expressly credited with a merit: he was the first to advance a principle of the state that is thought in its content as well, namely the will. For Hegel the mistake lies one step further on:
But since he conceived the will only in the determinate form of the individual will (as Fichte likewise later did), and the general will not as the rational element in and for itself of the will, but only as the communal element that emerges from this individual will as conscious, the union of individuals within the state becomes a contract.
Groundlines, § 258 note
This is a conceptual, not a political criticism: Rousseau’s volonté générale is counted up out of what individuals actually will – and is thereby a common, not a universal. Hegel holds the consequence to be disastrous and says so in a sentence about the French Revolution that has been quoted in both directions: the first tremendous spectacle of undertaking „to begin the constitution of a great actual state entirely afresh, from thought alone“ – and, because these were abstractions devoid of any Idea, at the same time „the most terrible and violent of events“.
And the other side: against Haller
Whoever concludes from this that Hegel wants to return to the pre-revolutionary condition should read the footnote to the same paragraph. It is aimed at Carl Ludwig von Haller, the spokesman of the Restoration, who had declared the rule of the more powerful to be „the eternal, unalterable order of God“. Hegel takes him apart over several pages and formulates in doing so a sentence that remains a touchstone to this day:
Hatred of law, of right determined legally, is the shibboleth by which fanaticism, feeble-mindedness, and the hypocrisy of good intentions reveal themselves and unfailingly betray what they are, whatever other garb they may otherwise choose to put on.
Groundlines, § 258 note, footnote
The state is therefore neither contract nor natural force. It is the form in which a commonwealth determines itself by thought-out, i.e. universal, laws and principles. Whoever derives the state from contract loses universality; whoever derives it from power loses law.
What the objection still reaches today
It reaches every construction that derives the binding force of the state from consent – from hypothetical consensus to the argument that one is after all free to emigrate. Hegel’s question remains uncomfortable: if validity follows from consent, what is valid as against the one who does not consent? He himself draws the consequence in § 100 note, with punishment as the example: the state makes the rationality of the concept of crime valid „with or without the consent of individuals“.
Whoever does not share the objection should at least answer it. It is the reason why § 258 contains the much-quoted and seldom-read sentence that the highest duty of individuals is „to be members of the state“ – a sentence that does not mean obedience but denies that membership is a choice. On the relation of state and individual see also Is the state God for Hegel?
Sources. Groundlines § 75 and note (the concept of contract; against Kant, Metaphysical First Principles of the Doctrine of Right, §§ 24–27), § 100 note (against Beccaria), § 161–§ 164 (marriage), § 258 and note with footnote (Rousseau; Carl Ludwig von Haller, Restauration der Staatswissenschaft, 1816 ff.), § 281. – In the glossary: Contract, The State, The State of Nature.