Materialism is a philosophy that precedes the Enlightenment era. It is based on the notion that all knowledge is obtained imperically, and that matter is the only source through which truth can be understood and applied. Furthermore, materialism implies that even abstract concepts like "rationality", "consciousness", and "society" are the result of relationships between material truths. Materialism's theoretical diametric opposite is the philosophy of idealism.

Some of the most well-known materilist theorists are Thomas Hobbes, John Locke, and later on Karl Marx, each of whom argue that a concrete material reality forms the basis of social systems as they exist today.

Thomas Hobbes' materialism begins with the notion that man itself can be reduced to matter.  He argues that "man is matter in motion".  At our core, humans are nothing more than self-motivating objects, gravitating toward that which we desire, and avoiding what we do not.  Our interactions with each other are also based on (and largely limited to) a material reality, where personal interactions are nothing more than market exchanges.  This specific theory is known as Possessive Individualism.

John Locke, though differing from Hobbes in many ways, is very much a thinker rooted in this materialist tradition.  Locke's famous notion of "inalienable rights", which are fundamental rights afforded to all human beings, are "Life, Liberty, and the Pursuit of Property."   Theories about private property, money, and labor form the basis of most of Locke's theories about political and social systems. 

Karl Marx stated famously in the Communifest Manifesto that "The history of all hitherto existing society is the history of class struggles."  For Marx, a material reality forms the basis of human society.   He borrows from Hegel to argue that through the production of some material object, we become conscious of having a self.    Historical materalism is Hegel's theory of the dialetic applied to a material reality - humans and their environment are simultaneously creating and recreating each other, based on the fulfillment of material needs (needs are also being created and recreated), and the product of all of this is the continuation of history.  Marx believes that those who have material power (capital, land, means of production), also have the power to create ideology and belief systems.  He argues that society develops from relationships between people in society, and specific sets of social relationships emerge from specific kinds of productions systems.   In short, virtually all of humanity has some level of interplay with a material, concrete, imperical reality.