Book II: Of Common-Wealth
Chapter 17: Of the Causes, Generation, and Definition of a Common-wealth
Chapter 18: Of the Rights of Soveraignes by Institution
Chapter 19: Of the severall Kinds of Common-wealth by Institution, and of Succession to the Soveraigne Power
Although the laws of nature require that human beings seek peace, and maintain that the establishment of contracts is the best means of doing so, the natural human hunger for power always threatens the safety of the contract. Hobbes concludes that there must be some common power, some sovereign authority, to force people to uphold the contract. This sovereign would be established by the people as part of the contract, endowed with the individual powers and wills of all, and authorized to punish anyone who breaks the covenant. The sovereign operates through fear; the threat of punishment reinforces the mandates of the laws of nature, thus ensuring the continued operation of the social contract.
The sovereign is the ruling force behind the contract; in the analogy between the abstracted contract and an artificial person, the concept of sovereignty is the soul of the artificial person and the sovereign itself, the head. This artificial person is a metaphor for the state in total, and Hobbes names this artificial person "Leviathan." Hobbes's description of the construction of the Leviathan draws upon the conclusions made in Book I about the state of nature and repeats its images: "The only way to erect such a Common Power, as may be able to defend them from . . . the injuries of one another . . . is, to conferre all their power and strength upon one Man, or upon an Assembly of men, that may reduce all their wills, by plurality of voices unto one Will . . . This is more than Consent, or Concord; it is a real Unitie of them all, in one and the same Person, made by Covenant of every man with every man, in such a manner, as if every man should say to every man, I Authorize and give up my Right of Governing my selfe, to this Man . . . on this condition, that thou give up thy Right to him . . . This done, the Multitude so united in one Person, is called a COMMON-WEALTH . . . This is the Generation of the great LEVIATHAN."
The purpose of establishing a commonwealth is to escape the state of nature and to provide peace and the common defense of the people; the sovereign is responsible for ensuring this defense. The sovereign may be an individual or a group of people, but Hobbes always speaks of the sovereign as "he." The power given to the sovereign permits him to do whatever he deems necessary in order to protect the commonwealth. All rights of the individual have been transferred to the sovereign in order for this protection to work, and the only right retained is the right of self-preservation, which was the original reason for establishing the Leviathan.
There are two ways of establishing a commonwealth: through acquisition (force) or through institution (agreement). The latter accords with Hobbes's description of how natural man raises himself out of the state of nature (through the establishment of the Leviathan). The former, establishing a commonwealth through force, means that a sovereign power takes control of a group of people, who--if they do not resist the acquisition and depose the sovereign--must consent to his control. Thus, a sovereign instituted by force is as much a part of the social contract as a sovereign instituted by agreement. Both have the same function--to protect society and secure peace--and both have the same rights relative to their subjects.
The rights of a sovereign are as follows: 1) Subjects owe him sole loyalty; 2) Subjects cannot be freed from their obligation to him; 3) Dissenters must yield to the majority in declaring a sovereign; 4) The sovereign cannot be unjust or injure any innocent subject; 5) The sovereign cannot be put to death; 6) The sovereign may determine what ideas are acceptable (he is the ultimate judge of philosophical/scientific first principles) and may censor doctrines that are repugnant to peace (ideas that may cause discord within the population); 7) The sovereign prescribes legislative rules; 8) The sovereign has judicial power in all controversies, civil and intellectual; 9) The sovereign may make war and peace with other commonwealths; 10) The sovereign may choose his counselors; 11) The sovereign has the powers of reward and punishment; and 12) The sovereign may make all civil appointments, including that of the militia. All rights of the sovereign correspond with the laws of nature deduced in Book I and the philosophical methods Hobbes has employed throughout his argument. The sovereign is both the foundation of all true knowledge and the embodied power enforcing civil peace.
Sparknotes editors, you need to review your definition of PLENUM in the glossary for Hobbes' Leviathan. A picture of the universe as a plenum makes a vacuum impossible.
The 15th Law of Nature is missing in this summary (Book I, Chapters 14-16, first page). Because of the missing number, the 15th Law is explained as the 16th, the 16th as the 17th and the 18th has become a short version of both the 17th and the 18th Law of Nature. Could you please look into this?
useful coverage of Hobbes basic terms. For further in-depth knowledge of these terms check out my blog where I have a short introductory essay to Hobbes state of nature being a state of war.