In the previous chapters, Hobbes has laid out a general case for how humans come to live in society, namely, that they are driven to it by fear. In order to have a more thorough picture of how society comes about, Hobbes directs his attention to human nature, so that we can precisely understand how humans go from this state of nature to society. As has already been noted, people are constantly moved by appetites and aversions, and as such, have certain ends in mind which they strive to attain. Since one or more men may desire the same end (for example, food or shelter), they are in a constant state of conflict and competition with one another. If man's appetites were finite this would not be so problematic, but as Hobbes argued in the above chapters, we are never satisfied with any amount of power (the means to attain certain ends), and are thus always in a constant power struggle with others.
While it may seem that in such a state of nature the strong would naturally triumph over the weak and some sort of natural equilibrium would be reached, due to the peculiar nature of power this can never be so. Men are by nature equal in their powers, as even "the weakest has strength enough to kill the strongest, either by secret machination, or by confederacy with others, that are in the same danger as himself." From this equality in the state of nature where even the weak can kill the strong, combined with a finite amount of resources and distrust of other men, arises a perpetual state of conflict. Without a common power to mediate amongst men and distribute resources, the state of nature is nothing but a state of constant war, where "the life of man [is] solitary, poor, nasty, brutish, and short.
Some people might object to Hobbes' rather pessimistic view of human nature, but he urges the reader to look at experience and judge whether he is correct. After all, he reasons, you lock your doors when you are away from home, and carry arms to defend yourself when you are traveling. Doesn't that reveal that humans by nature are distrustful of one another and constantly competing with each other for desired ends? One might also object that Hobbes' state of nature never existed. Here Hobbes admits that while such a period of time may never have occurred and is merely hypothetical, we can see evidence of this during times of civil war, and even when we look at the way of life of the "savages" in the Americas. Whether this state of nature actually existed is inconsequential, since Hobbes' argument here is psychological rather than historical. Again, Hobbes believes his argument can be validated recursively, so we should wait and see if what he derives from this theory of human nature is valid.
Hobbes' state of nature is purely descriptive rather than normative, that is to say, he does not believe there is anything necessarily wrong with the passions and desires that propel us towards war with one another. In fact, in a state of nature where there is no common power, "nothing can be Unjust. The notions of Right and Wrong, Justice and Injustice have there no place. Where there is no common Power, there is no Law; where no Law, no injustice." As Hobbes' stated before in his initial treatment of the passions, what inclines us toward peace is a general fear of death. The terms of peace that men come into agreement upon, which are dictated to us by reason, are called the Laws of Nature.
To understand the Laws of Nature one must first understand the fundamental right of nature these are based upon. The right of nature is the liberty each person has to do anything within their means for self-preservation. Correspondingly, a law of nature is a rule, discovered by reason that forbids one to anything to hurt oneself, or to take away the means of self-preservation. Through reasoning that in the state of nature we are at war due to our quest for self-preservation, we discover the first fundamental law of nature, that man should "seek Peace, and follow it." The second fundamental law of nature derives from this first one, and states that we should lay down this absolute right of nature "and be contented with so much liberty against other men, as he would allow other men against himself." In other words, we should restrain ourselves from pursuing ends by any means necessary, insofar as other people agree to do the same.
In observing this second law of nature, humans "lay down" their right of nature. This can either be done by simply renouncing it - stating, 'I no longer have the right to do whatever it takes to stay alive regardless of who benefits from this action' - or by transferring it: placing this right in someone else's hands for some specific benefit. Merely renouncing the right to nature is a violation of the first law of nature, since you give up the right to defend yourself without good reason. But transferring this right to a mutually agreed upon power, namely, through a contract, follows from both laws of nature. You agree not to attack someone so long as they agree not to attack you, and both people transfer their rights of self-preservation to a common authority. A covenant is a contract made whereby one or more parties are bound to some future obligation (a contract can be a simple exchange of goods for services, which ends after the transaction ends).
It should be noted that Hobbes believes a covenant is only valid if a common power can enforce the terms of the contract. If two people simply agree not to attack one another without something to enforce this they have no reason to obey the covenant. One might argue that the desire for peace could be enough to enforce the terms of the contract, but in this case, the desire to cheat and, say, attack the other person once their guard is down would be too tempting. In fact, not only would it be tempting, it would also be the most rational course of action.
For example, if I have $10 and agree not to steal your $10 on the condition that you do the same, I have every reason to still try to attack you and steal your money. In the worst case scenario I fail in my offensive and am left with $10; and in the best case scenario I conquer you and have a total of $20. This is exactly the state of affairs between us prior to agreeing to our pact of non-aggression. But if there is a common power to enforce this covenant that would punish me for trying to steal your $10, then the situation is radically different. If there is a fine of $30 for trying to steal from others, the risk of attacking you (lose $30) is now greater than the reward of not attacking you (gain $20). Thus, it is only when a common power is there to enforce the terms of an agreement can a covenant be valid. (Correspondingly, a contract or covenant made in the state of nature, that is, in the absence of a power, is void).
From these first two laws of nature, Hobbes then deduces the third law of nature, "that men perform their Covenant made; without which, covenants are in vain, and but Empty words; and the Right of all men to all things remaining, wee are still in the condition of Warre." In other words, it is in our interest to obey our covenants, since the rewards for doing so (peace) outweighs the risk of breaking them (war). From this law of nature comes justice, so that to obey a covenant is justice, and to break it is injustice. With these first three laws of nature in hand, Hobbes then goes on to offer nineteen total laws that are derived from these initial three. These range from, but are not limited to, graciousness, revenge, pride, arrogance, and many others, which in the most general sense are similar the golden rule: "do not that to another, which thou wouldst not have done to thyself." These nineteen laws make up moral philosophy, which according to Hobbes, "is nothing else but the science of what is good, and evil, in the conversation, and society of mankind."
The last chapter of Book I sets the stage for Hobbes' analysis of "The Commonwealth" in Book II. When a covenant is made between two or more men it is said to be made between two or more persons, namely, one whose actions and words are either one's own (natural person) or represents the words and actions of another (artificial person). With regard to an artificial person, the actor is the person (or body) that performs a given act, while the author is the person (or persons) whose actions these are. (In the case of a natural person, the actor and author are the same.) In going from the state of nature to society, a set of natural persons agree to a covenant, whereby a common power is established as an artificial person to enforce the terms of the contract. This artificial person serves as the representative or actor of all those who agreed to the covenant. Thus, all signatories of the covenant are the authors of any and all actions performed by the artificial person.
Hobbes' social contract theory is one of Leviathan's most lasting contributions to philosophy, as it sets the stage for later contractarians like Locke (Two Treatises on Government, 1689), Rousseau (The Social Contract, 1762), and more recently, John Rawls (Theory of Justice, 1971). Locke's social contract differs from Hobbes' mainly in that he views human nature as naturally peaceful, and does not believe that man in this state would be naturally driven by warring desire and appetites. Equality also takes on a different meaning for Locke in his state of nature, for equality exists in this state not because anyone has the power to kill anyone else, but because no one is subordinate to any one person or power. Eventually people are forced to leave the state of nature when a state of war breaks out, which occurs when one man tries to subordinate another man and take his goods. Once the state of nature is corrupted by this state of war man must set up a government to protect one's goods.
Similar to Locke, Rousseau believes that in the state of nature man is born free and no man is naturally subordinate to another. Due to human nature the state of nature is untenable for a man's self-preservation - a point that all three philosophers agree upon - hence the need to establish a state. After men form the social contract, they substitute moral equality for the natural equality that existed in the state of nature. That is to say, each man has a right to be treated equally by the sovereign. Rousseau wavers somewhat in his description of man in the state of nature. In his earlier work, Discourse on the Origin of Inequality (1754), he describes the state of nature as a relatively peaceful state where men live within their means. Later in his life, particularly in his Confessions (1770), Rousseau would return to this theme - partly out of frustration with the politics of the day that attacked him philosophically and personally - and express a desire to return to this idyllic state of nature where man is not corrupted by society.
One of the criticisms Rousseau made of Hobbes's state of nature is that Hobbes describes man existing in the state of nature as pre-social, yet many of the qualities of man in this state are social ones. For instance, he describes men as being driven by pride, which can only happen in a social environment; indeed, most of the qualities Hobbes' ascribes to man in the state of nature are inherently inter-personal. In fact, Hobbes says that man can never be content with any amount of resources, since he may see his neighbor has more and feel either threatened or envious. He therefore presupposes neighbors. Thus, to claim that man's life is "solitary and brutish" is misleading. Whether this threatens Hobbes' overall argument is up to the reader. Rousseau believed this showed evidence of some form of society existing in the state of nature, although Hobbes would likely argue that if this was indeed a societal form, there was still a need to establish a more complex and ordered society around a sovereign.
While much has been said of the place of fear in Hobbes' philosophy, one should take particular notice of the place of reason within it. While perhaps not stated explicitly, by tying the social contract to our desire for self-interest Hobbes is implying that it is rational for one to enter into society, and to perform the obligations it requires of us. Justice and rationality become then intertwined, as evidenced in his claim that "Justice therefore, that is to say, Keeping a Covenant, is a Rule of Reason, by which we are forbidden to do any thing destructive to our life." As will become particularly apparent in his later treatment of a subject's specific obligations to the sovereign, Hobbes' will base these "rules of reason" almost entirely on self-interest, taking the form "if you wish to preserve your life, you ought to do..."
This emphasis on rationality is one of the aspects of Hobbes' philosophy that prefigures the Enlightenment. Historically, Hobbes may not have lived or published in the time period commonly known as the Enlightenment, but his belief that proper reasoning shows man the way out of the state of nature, as well as his constant emphasis on subjecting any traditional thought or opinion to our own individual reasoning, sets the stage for thinkers like Locke and Rousseau. Even his concept of the natural equality of man, though this inheres in man's equal right to kill one another, is one of the central tenants of the political thought that follows him. Again, Hobbbes therein breaks from the philosophy of the Greeks. Aristotelian thought claimed that some men are naturally slaves and others are naturally masters, while Plato advanced the idea of man's place in society arising from his "natural strengths," with a Philosopher King - who has superior rational abilities - ruling over his contemporaries.