Thomas Hobbes's Leviathan, published in 1651, is one of the defining works of modern political philosophy. Written during an age of civil war, religious conflict and disputed sovereignty, it asks how peace can be secured among human beings whose desires, fears and judgements repeatedly bring them into competition. Hobbes answers by constructing a theory of human nature, obligation, political authority and religion around the image of the commonwealth as an artificial person.
The title invokes the immense biblical creature described in the Book of Job. Hobbes transforms it into an image of political power. A commonwealth is an artificial body created by human agreement: sovereignty is its soul, magistrates its joints, reward and punishment its nerves, wealth its strength and public safety its purpose. The state is not presented as a natural organism existing independently of people. It is made through their acts of authorisation.
Part I, “Of Man,” begins with sensation, imagination, speech and reasoning. Hobbes's materialism treats mental life through motions produced by bodies. Sense initiates thought; imagination is decaying sense; trains of thought follow patterns shaped by desire and previous experience. Reason is not a mysterious faculty that directly sees eternal essences. It is reckoning with names and consequences.
Language enables knowledge but also creates error. Words can support definition, inference and collective agreement, yet unclear or inconsistent usage produces absurdity. Hobbes therefore places careful definition at the centre of philosophy. His political argument depends upon distinguishing liberty, right, law, covenant, person and sovereignty with unusual precision.
Human action begins in appetite and aversion. What a person desires is called good by that person; what is avoided is called evil. Hobbes does not assume a highest natural good that harmonises everyone. Felicity is continued success in obtaining desired objects, and power is the present means to future apparent good. Because desires continue and security remains uncertain, people seek power after power.
Chapter XIII presents the famous state of nature. Hobbes argues that human beings are sufficiently equal in vulnerability and hope that no one is naturally secure from another. Competition, diffidence and glory generate conflict when there is no common authority capable of enforcing rules. The “war of every man against every man” describes not constant fighting but a known disposition towards violence during a time without assurance of peace.
Life in this condition is insecure because industry, agriculture, navigation, knowledge and cooperative achievement cannot confidently flourish. Hobbes's bleak description does not claim that everyone is continuously cruel. It shows how fear and rational mistrust can make conflict reasonable even among people who would prefer peace.
The right of nature permits each person to use available means for self-preservation. A law of nature is a rational precept directing people towards peace when it can be obtained. The first laws require seeking peace and being willing, when others are also willing, to lay down enough liberty for mutual security. Covenants create obligations, but words alone cannot secure performance where there is no coercive power.
Part II, “Of Commonwealth,” explains political creation. Individuals covenant with one another to authorise a person or assembly to represent them. The sovereign is not a party to this founding covenant in the same way as subjects; the sovereign's acts count as authorised acts of the political person. Hobbes uses this structure to defend undivided and extensive sovereign power.
Sovereignty may be monarchical, aristocratic or democratic, though Hobbes favours monarchy. Whatever its form, it must control legislation, judgement, war, peace, public teaching and appointment to offices. Dividing final authority invites rival claims and a return to civil conflict. Political obligation is grounded less in affection for rulers than in the need for a determinate public power capable of securing peace.
Hobbes's theory does not eliminate all liberty. Liberty is the absence of external impediments. Subjects remain free where law is silent, and no covenant can remove the fundamental effort to resist death. Hobbes discusses circumstances in which obedience ceases, especially when the sovereign can no longer provide protection. The relation between protection and obedience is one of the work's most important qualifications.
Civil law is the sovereign's command communicated through public signs. Hobbes examines crime, excuse, punishment, reward, public ministers, counsel and the material support of the state. His analysis treats institutions as mechanisms of representation and coordination rather than as expressions of an independently existing moral hierarchy.
Part III, “Of a Christian Commonwealth,” and Part IV, “Of the Kingdom of Darkness,” occupy nearly half the work. Hobbes interprets scripture to deny any independent coercive authority to churches within a commonwealth. Private inspiration cannot establish publicly binding doctrine. Ecclesiastical power must be subordinate to civil sovereignty if rival spiritual jurisdictions are not to reopen political conflict.
The theological argument is inseparable from the political argument. Hobbes criticises inherited doctrines, scholastic philosophy, demonology and clerical claims that create fear or divided allegiance. His extensive biblical interpretation aims to show that religion cannot legitimately supply a competing earthly sovereign.
The Review and Conclusion returns to political obligation, conquest, resistance and the circumstances of Hobbes's own divided nation. It also qualifies and defends arguments made throughout the book. Leviathan closes as both a systematic philosophy and an intervention in a crisis of authority.
Modern readers continue to dispute whether Hobbes establishes absolute sovereignty, whether authorisation can justify such extensive power and whether fear provides an adequate foundation for political community. Yet his central problems remain recognisable: how can people cooperate without reliable trust, what makes authority legitimate, how much liberty is compatible with security, and who decides when moral and religious convictions conflict?
Leviathan's lasting achievement is to make political order an object of explanation rather than assumption. Authority is constructed from vulnerable individuals seeking peace; it must operate through representation, law and public power; and its claim upon obedience remains tied to its capacity to protect.