In his book, Leviathan (1651), Hobbes puts forward an argument for a social contract – influenced to some degree by the English Civil War, he suggests that the only way to avoid chaos, civil war and bellum omnium contra omnes (“the war of all against all”) was for individuals to sacrifice some of their 'natural rights', and to institute sovereign central government: the 'Leviathan' for which the book is named. In general terms, a 'social contract' is the imaginary device by which individuals living without government or any form of alliance, come together to form a society and accept some form of obligation to one another, and thereafter binding themselves to a political sovereign whose purpose is to enforce those obligations.
According to Hobbes' theory, without society, we would live in a 'state of nature', what he considers to be the natural state of humankind, where each individual has unlimited freedoms, or 'Rights of Nature'. He argues that whilst some individuals are more intelligent or stronger than others, nobody is so elevated in ability to be without fear of violent death. Hobbes holds that it is self-defence against such an attack is the highest human necessity, and the ultimate goal of reason. Rights are borne of necessity, and within the state of nature all people have the right to everything and anything there is – and because of this there will be a constant rights-based war of all against all. Hobbes calls life in the state of nature 'solitary, poor, nasty, brutish and short'.
The final cause, end, or design of men (who naturally love liberty, and dominion over others) in the introduction of that restraint upon themselves, in which we see them live in Commonwealths, is the foresight of their own preservation, and of a more contented life thereby; that is to say, of getting themselves out from that miserable condition of war which is necessarily consequent, as hath been shown, to the natural passions of men when there is no visible power to keep them in awe, and tie them by fear of punishment to the performance of their covenants...
(Book II, Ch. 17)
Hobbes states that in order to gain lasting self-preservation, the goal of reason, a stable society must be created, and all individuals within that society are required then to relinquish their Right of Nature, and thus enter into a social contract with one another. For example, an individual would cede their right to kill any other individual, provided that every other individual also ceded their right to kill. People agreeing to the contract retain only those rights over others which they are content to allow everybody else to retain over themselves – so in return for being granted freedom of speech, each person must also accept that all other people would be granted freedom of speech also.
However, due to humanity's natural desire for power, the social contract will always be under threat, and a central, sovereign authority must be established in order to force people to uphold it. Such a sovereign would be authorised by the contracted individuals, as part of the contract, possessing the individual powers and wills of all, and sanctioned to judge and punish and person who breaks the contract. Because there is fear of punishment, the presence of the sovereign reinforces the mandates of the laws of nature, hence ensuring the continued operation of the social contract. Hobbes calls this arrangement the 'commonwealth'.
Hobbes accords the sovereign (who may be one person or a number of people, although Hobbes always refers to the sovereign as 'he') twelve rights, granted in order to maintain the social contract.