In breaking with the traditional views of the origin of political power and turning to reason for its justification, he introduced modern political philosophy and social theory, as we know it.
For this, he has been referred to as the father of modern analytic philosophy.
In doing so, he managed to annoy everybody from the Church, to Parliament, to the Monarchy and Descartes, whose views he vehemently objected to.
Hobbes' philosophy is probably the most materialist philosophy of the 17th century. He rejected Aristotelian and scholastic philosophy, which taught that the world could be understood through the knowledge of the essence of things.
He instead favored the concept of mathematical calculation and the "new" philosophy of Galileo and Gassendi, which viewed the world as matter in motion.
His thinking was so original and forceful for the times that he was considered an atheist (he really wasn't, but insisted that theological disputes should be kept out of politics) and enemy of religion. It didn't help that he believed in the mortality of the soul.
In his major work, The Leviathan, a masterpiece of moral and political philosophy, Hobbes states:
"The universe is corporeal; all that is real is material, and what is not material is not real."
In it, he also presents a pessimistic view of human nature. He regards man’s natural state or "state of nature" as one of selfishness and in perpetual struggle against his fellow man. He states that man's actions are governed by basic, purely selfish desires (the need to relieve himself from discomfort and to do whatever that takes).
He sees human nature without society to temper it, as in a "state of war," and as an existence that would be "solitary, poor, nasty, brutish and short." The only way to achieve a better life, Hobbes declares, would be to make "contracts" with our fellow beings.
The result would be a "commonwealth" in which we give up some of our individual freedoms in order to create a society that benefits everyone.
The creation of the commonwealth would create a new, conglomerate person, the Leviathan, who is entrusted with social order and responsibility. As Hobbes put it '...it is as if every man should say to every other, "I authorize and give up my right of governing myself to this man or assembly of men, on this condition, that thou give up thy right to him, and authorize all his actions in like manner." '
The only way out of man's "state of nature" would be complete submission to this single, absolute power. The best option, according to Hobbes, for this single power would be a hereditary monarch.
Of course, because the people themselves contract together, they make the "free gift" of a part of their rights to the sovereign. He in turn is obliged to make their safety and well being the highest law.
We can see from this that Hobbes believed that this system of government was preferable to a democracy. He wrote that,
"All mankind is in a perpetual and restless desire for power" and that the natural condition of human beings, that is to say, ungoverned human beings is war, "every man against every man."
He felt that a monarchy was preferable to any other form of government because for any government to be effective, it had to have absolute authority. This is more achievable and efficient with a sole governing source.
Ultimately, Thomas Hobbes' work is known for being influential in two ways. First, was his reaction against religious authority, particularly scholastic philosophy and his defense against it, and secondly, his involvement in the emerging scientific method.
Both affected how he expressed his moral and political ideas.