Thomas Hobbes of Malmsbury was a man who lived with fear. In his autobiography, Hobbes recounted that on the day of his birth in 1588, his mother learned that the Spanish Armada had set sail to attack England. This news so terrified Hobbes's mother that she went into labor prematurely, and thus, writes Hobbes, "fear and I were born twins together." Fear is a significant theme in Hobbes's writing, structuring both his written accounts of his life and the Hobbesian philosophical system.

Leviathan, Hobbes's most important work and one of the most influential philosophical texts produced during the seventeenth century, was written partly as a response to the fear Hobbes experienced during the political turmoil of the English Civil Wars. In the 1640s, it was clear to Hobbes that Parliament was going to turn against King Charles I, so he fled to France for eleven years, terrified that, as a Royalist, he would be persecuted for his support of the king. Hobbes composed Leviathan while in France, brilliantly articulating the philosophy of political and natural science that he had been developing since the 1630s. Hobbes's masterwork was finally published in 1651, two years after Parliament ordered the beheading of Charles I and took over administration of the English nation in the name of the Commonwealth.

The argument in Leviathan for the necessity of absolute sovereignty emerged in the politically unstable years after the Civil Wars, and its publication coincided with that of many Republican treatises seeking to justify the regicide (killing of the king) to the rest of Europe (John Milton's Tenure of Kings and Magistrates is a famous example of these regicide tracts). Not only was the political argument of Leviathan controversial at the time of its publication, but the philosophical method employed by Hobbes to make his claims also scandalized many of his contemporaries—even those writers, such as Robert Filmer (the author of the Royalist tract Patriarcha), who otherwise supported Hobbes's claims for absolute sovereignty.

Hobbes's materialist philosophy was based upon a mechanistic view of the universe, holding that all phenomena were explainable purely in terms of matter and motion, and rejecting concepts such as incorporeal spirits or disembodied souls. Consequently, many critics labeled Hobbes an atheist (although he was not, in the strict sense). Associated with both atheism and the many deliberately terrifying images of Leviathan, Hobbes became known as the "Monster of Malmsbury" and the "Bug-bear of the Nation." In 1666, Hobbes's books were burned at Oxford (where Hobbes had graduated from Magdalen College in 1608), and the resulting conflagration was even blamed in Parliament for having started the Great Fire of London. The chaotic atmosphere of England in the aftermath of the Civil Wars ensured that Hobbes's daring propositions met with a lively reaction.

Hobbes knew that Leviathan would be controversial, for not only did the text advocate restoration of monarchy when the English republic was at its strongest (Oliver Cromwell was not instituted as Lord High Protector until 1653, and the Restoration of Charles II did not occur until 1660), but Hobbes's book also challenged the very basis of philosophical and political knowledge. Hobbes claimed that traditional philosophy had never arrived at irrefutable conclusions, that it had instead offered only useless sophistries and insubstantial rhetoric; he thus called for a reform of philosophy that would enable secure truth—claims with which everyone could agree. Consequently, Hobbesian philosophy would prevent disagreements about the fundamental aspects of human nature, society, and proper government. Furthermore, because Hobbes believed that civil war resulted from disagreements in the philosophical foundations of political knowledge, his plan for a reformed philosophy to end divisiveness would also end the conditions of war. For Hobbes, civil war was the ultimate terror, the definition of fear itself. He thus wanted to reform philosophy in order to reform the nation and thereby vanquish fear.

Earlier in the seventeenth century, Francis Bacon—for whom Hobbes had served as secretary in his youth—had also proposed a reform of philosophy, a reform he called the "Great Instauration." Bacon's program was an inductive philosophy based upon the observation of natural facts ("inductive" reasoning derives general principles from particular instances or facts); the experimental manipulation of nature of Bacon's scheme was very influential for the development of the historical period commonly called the Scientific Revolution, and also formed the backbone of the English Royal Society. Like Hobbes's, Bacon's system rejected traditional philosophical knowledge as untrustworthy, instead embracing nature as the only sure basis for all claims for truth. But Hobbes argued that the experimentalist program was also unsuccessful in providing secure, indisputable knowledge. Hobbes therefore rejected the Baconian system and argued vehemently against it. Hobbes's own deductive scientific philosophy was not experimental—in "deductive" reasoning, a conclusion follows necessarily from the stated premises, rather than being inferred from instances of these premises—but Hobbes maintained that it provided better understanding of the universe and society than both traditional philosophy and experimental science.

Leviathan attempted to create controversy in politics and in science, radically challenging both contemporary government and philosophy itself; yet, despite its very invocation of controversy, Leviathan sought ultimately to annihilate controversy for good. Hobbes's philosophical method claimed to provide indisputable conclusions, and its depiction of the Leviathan of society suggested that the Hobbesian method could put an end to controversy, war, and fear. Hobbes's philosophy was highly influential in certain sectors (Hobbesism was a fashionable intellectual position well into the eighteenth century). However, Hobbes, who died in 1679, never lived to see his work achieve the widespread and totalizing effects for which he had hoped. Excluded from the Royal Society for his anti-experimentalist stance and derided by many contemporaries as an immoral monster, Hobbes neither transformed the nation nor reformed philosophy as he had envisioned. Nonetheless, Hobbes has had a lasting influence in the history of Western philosophy, as he is credited with inaugurating political science; his crowning achievement, Leviathan is still recognized as one of the greatest masterpieces of the history of ideas. Written during a moment in English history when the political structure, social structure, and methods of science were all in flux and open to manipulation, Leviathan played an essential role in the development of the modern world.