Chapter 14: Of the first and second Naturall Lawes, and of Contracts
Chapter 15: Of other Lawes of Nature
Chapter 16: Of Persons, Authors, and things Personated
A "Law of Nature" is a general rule that is discovered through reason. Such a law affirms human self-preservation and condemns acts destructive to human life. Unlike a civil law, which must be written down and publicized in order to be known, a law of nature is natural and inherently known by all because it can be deduced by innate mental faculties (reason, philosophy). Having described the horrors of the state of nature, in which fear reigns supreme, Hobbes concludes that natural man, in order to preserve life, must seek peace. Thus the first law of nature is: "That every man, ought to endeavour Peace, as farre as he can hope of obtaining it; and when he cannot obtain it, that he may seek, and use, all helps and advantages of Warre. The first branch of which Rule, containeth the first, and Fundamental Law of Nature; which is, to seek Peace, and follow it. The Second, the summe of the Right of Nature of Nature; which is, By all means we can, to defend our selves." Natural law demands that we seek peace because to seek peace is to fulfill our natural right to defend ourselves.
The second law of nature follows upon the mandate to seek peace: We must mutually divest ourselves of certain rights (such as the right to take another person's life) in order to escape the state of natural war. This second law requires: "That a man be willing, when others are so too (as farre-forth, as for Peace, and defense of himself he shall think it necessary, to lay down this right to all things; and be contented with so much liberty against other men, as he would allow other men against himself." This mutual transferring of rights is called a contract and it is the basis of the notion of moral obligation. For example, I give up my right to kill you if you give up your right to kill me. For the sake of self-preservation, people will give up their rights only when others are willing to do the same. (However, the right of self-preservation is the one right that can never be given up, because it is the right upon which the contract is founded in the first place.)
From these first two laws of nature, Hobbes proceeds to deduce a series of other laws, each one building upon the last in the geometric fashion of which he is so fond. The third law of nature states that it is not enough simply to make contracts, but that we are required to keep the contracts we make. This law of nature is the foundation for the concept of "Justice." But because of the human desire for power, there is always incentive to break the contract, despite the logic of the third law and the natural mandate to preserve our own lives. Other natural laws--and eventually the concept of sovereignty--must come into play in order to preserve the functionality of this third law. But it should be recognized that the first three laws of nature, as an autonomous triad, have already provided a plan for escaping the state of nature.
The fourth law of nature is to show gratitude toward those who maintain the contract so that no one will regret having complied with the contract. The fifth law states that we must be accommodating to others for the purpose of protecting the contract and not quarrel over minor issues lest the contract collapse. The remaining laws are summarized as follows: 6) We must pardon those who have committed offenses in the past; 7) Punishment should be used only to correct the offender and to protect the contract, not for gratuitous retribution (e.g. "an eye for an eye"); 8) People must avoid making signs of hatred or contempt toward others; 9) Pride should be avoided; 10) One should retain only those rights that one would recognize in others; 11) Equality and impartiality in judgment should be maintained at all times; 12) Resources that cannot be divided, such as rivers, must be shared; 13) Resources that cannot be divided nor shared in common should be assigned by lottery; 14) Lots are of two sorts: natural (either through primogeniture or through first seizure of the resource) or arbitrary (random determination of possession); 16) Individuals who work to preserve the peace should be left in peace; 17) Disputes must be settled by an arbitrator (as Hobbes had already concluded in his discussion of the determination of first principles); 18) No one with self-interest may be an arbitrator; and 19) Witnesses and facts must be brought to bear in arbitration, lest decisions be made by force, contrary to the law of nature.
A law of nature is valid if it conforms to this general rule: "Do not that to another, which thou wouldst not have done to thy selfe." The nineteen laws of nature are the sum of morality, and the science that determines them is known as "moral philosophy."
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.