This thesis has three main aims. The first is to clarify Hobbes's contractualism and to derive the nature, origins and solutions of war from key concepts in Hobbes's theory. The second aim is to analyze whether there is any connection between Hobbes' contractualism and civil war or conflict given that Hobbes grew up when there was civil war in his homeland and he expressed his views on civil war in the book Leviathan. A third aim is to use Hobbes' contractualism to illuminate and try to explain civil conflict in Afghanistan, a country that has been marked by civil conflicts for almost five decades.  For a civil conflict to be classified as an armed conflict, at least one of the parties must be a non-state actor, and Afghanistan is a country where the Taliban is classified as a non-state actor whose aim is to seize state power by force. Afghanistan is a country that is known for its civil conflicts therefore it will be interesting to prefer that country as an example in this work.  When analyzing Hobbes' contractarianism and civil war, Hobbes' book Leviathan was used to explain Hobbes' view on civil war and how the inhabitants can cooperate and sacrifice their natural rights to form a society with a sovereign who can keep peace and make laws that can be beneficial for all the people. The conclusion is that Hobbes makes good arguments in the book Leviathan for how to resolve civil conflicts and how citizens benefit from making peace with each other through a sovereign.