Social contract theories: a comparison of Hobbes, Locke and Rousseau

History of social contract theories
Social contract theories have been around since the first forms of society arose in the ancient world, one of the best known dialogues being Plato's De Res Publica, which sets out that the principle of social contract is to establish convenants in order to enforce the mutual agreement neither to inflict injustice, nor to suffer injustice.

Marsilius of Padua would develop a theory quite similar to modern-day social contract theories. In his writing, Defensor Pacis (1324), he states that not the Church, but the prince has autonomy and the right of jurisdiction within his territory, only to be bound by mandate of the people and their consent, as the people are the source of all political power and government. The prince has to carry out his obligations- if he fails to do so by violating the law, he will be punished.

Common features of and differences between Social Contract Theories: a comparison

1. State of Nature
1.1. Hobbes
The original state is the State of Nature, in which men have no order, no law and no bodies to enforce law. How the "State of Nature" is viewed by a social contract theorist, depends on the context in which the author himself is placed: witnessing a series of civil wars, it is understandable that Hobbes predicted life in a state of nature to be "brutish and short" and that only absolutism would make an end of this actual state of war in the seventeenth century.

1.2. Locke
Although Locke's State of Nature, a pre-political state, is not considered devoid of morality- on the contrary, the State of Nature is the state of liberty where people even recognize the Law of Nature and therefore do not harm each other- the equality of men and a lack of organization is what will amount to a rather insecure and unsafe state of being. Emphasizing the individual right to "Life, Liberty and Estate", the right to Property, it should not surprise that Locke has written his thesis in favor of the rising middle class in the spirit of the early Age of Enlightenment. That is probably the main reason why Locke's conceptions of the "State of Nature" and the social contract cannot be as unyielding as Hobbes' conceptions were- but then again, Locke's writings were published after the Glorious Revolution (1688); worlds apart from the English Civil War that has inspired Hobbes to writing his infamous Leviathan (1651).

1.3. Rousseau
Rousseau spent his days in the French salons chatting about on intellectual topics, but it is presumably Rousseau who marked the end of the 'Ancien Régime' with his criticism of Louis the Great and his successors until Louis Capet (XVI). His view of the "State of Nature" is surprisingly positive: the State of Nature seemed like paradise, but the introduction of property and civilian culture has made it impossible for man to stay in the State of Nature. In that respect,
"Contrat social" (1780)  is clear and concise on the importance of establishing society on a "volonté générale" rather than on a "volonté de tous".

General comments
I would go as far as to say that Hobbes' Leviathan accurately describes the world we live in, whereas Locke seemed merely blinded by the favor of his audience: as life in the State of Nature was all that perfect and men would, by nature, live up to their obligations, then it is rather inconsistent to suppose that only the acquisition of property leads to unsafety and that a simple increase in conflicts would amount to a state of war.

It seems to me that, behind his rhetoric, Locke makes a quite similar point. His State of Nature may not be equal to a State of War like it is in Hobbes' view, but the State of Nature will result in a State of War to the slightest somehow.
I would not say that an abolute sovereign is the solution to modern global troubles (on the contrary), but it goes to show that on a global scale, the lack of effective government indeed in the event results in a poor and brutish life, overall unsafety and insecurity.

2. Pactum unionis and (subsequent) pactum subjectionis
Common to all social contract theories are either pactum unionis or pactum subjectionis, or a simultaneous application of both pacta, sometimes referred to as the first being the "phase of historical fact" and the latter being the "phase of legal reason" The pactum unionis implies that men have passed from a State of Nature to a State of Society by means of a contract by which they have imposed on themselves the obligation to respect each others rights, thus, a pact with horizontal effect; the pactum subjectionis implies that people undertake to obey the government, chosen by them
(W. Friedman, Natural Law and Social Contract, London 1967, p.118).

Comparing Hobbes, Locke and Rousseau, it becomes clear that Hobbes has envisioned solely a pactum subjectionis, for only an absolute sovereign could govern effectively; Locke envisioned the pactum unionis and pactum subjectionis subsequently; in Rousseau's theory, as the sovereign is inherent to "volonté générale", as there is no higher authority or power, no other pact than the pactum unionis is essential to his conception of social contract.

With regards to Locke, the subsequent conclusion of the pactum unionis and subjectionis is stated clearly: "The great chief end of men's uniting into commonwealths and putting themselves under government, is the preservation of their property (Life, Liberty and Estate).

3. Marking the end of the Ages of "divine law" and Medieval incorporate personality
One main feature that is common to all social contract theories, is that the source of all political power lies within the people; this view distincts the early Ages of Enlightenment from the Medieval Period, in which the idea of the existence of "divine law", granting political authority to the sovereign, would govern the people.
According to Friedman, another common feature is the individualistic and "atomistic conception" of society, in that the state is the legal creation of indivdual will, as opposed to the organic view of society and incorporate personality as was applicable to society in the Medieval.

4. Transfer of natural rights
In the Hobbesian view, natural reason dictates man to self-preservation. In pursuit of the escape of this state of permanent insecurity, man transfers all of his rights to the sovereign. The power of the ruler needs to be absolute, man should obey without any reservations. There is no contractual right by which subjects could demand the fulfilment of obligations by the Leviathan. "Governments without the sword are but words, and of no strength to secure man at all."
Hobbes' thought construction is utilitarian, in the sense that nothing but self-interest has led man to invoke the security of an absolute ruler who carries the sword on behalf of man. (Friedman, 1967)

Unlike Hobbes, Locke's social contract is conditionally: government is regarded a party to the contract and man is able to demand the fulfilment of obligations. Locke's social contract serves to limit the power of government and secure the right of property. Man does not transfer these fundamental rights of life, liberty and estate. Natural rights are transferred only partially, solely on the purpose of not rendering the effect of the contract. These rights are the right to self-preservation, which is transferred to Parliament, and the right to punish, which is transferred to the executive.