In the realm of Western political philosophy, there are many political theories that are found in the dominant discourse. First, there is social contract theory, or contractarian theory; this theory states that individuals must adhere to the communal sense of good and evil in order to maintain that society. According to Hobbes, there is a struggle between the laws and rights of nature of all human beings. People have the right, or the liberty, to do whatever they can to stave off death and see to their interests; however, in order to interact with a group of other human beings, they must voluntarily give up those rights of nature to an extent to allow other people to have a communal sense of civilization. This is known as a social contract theory, wherein a group of people understand that they cannot just follow their urges, as that would disrupt the society in which they live. Socrates also followed this theory, as he believed one should subordinate self-interest in order to live in a society that oversees its peers. In classic liberalism/libertarianism, limited government is the key to a successful society; individual liberty and choice is placed above everything else, and people should be allowed to pursue their self-interest. Free market capitalism is heavily linked to this principle, as it is thought that the concept of a free market would allow people to realize their destinies according to their will and resources. John Locke was known as the Father of Classical Liberalism, and believed that people earn their property through the labor expended to create their goods and properties. Adam Smith also believed in classical liberal economics, and stated that the government should be as separate from possible, to allow material self-interest to make society more equitable. According to social theorist Karl Marx, the bourgeoisie, who are the ruling elite, controls through various means all the power and resources that are available to the detriment of the working class. This leaves the 'proletariat' unable to rise above their station or gain any agency in the government or nation to which they are dedicating their hard work and resources. Marx, in The German Ideology, predicted that, in any such system like this, conditions would gradually get worse and worse for the proletariat until such time as they became sufficiently class-conscious (aware of the rights and agency they are being denied). According to communitarianism, the individual is seen as an inextricable and important part of communal units, whether that be a family unit or an entire society. Public spaces are the places where real human life happens, and so traditions and communication are incredibly important to the maintenance of those societies. These social interactions and traditions, according to Robert Putnam, form social networks and build social capital, which is used to build and maintain a democracy. The goal of communitarians is to maximize this social capital and use it to maintain civil societal institutions.
In the capabilities approach, individuals' own capabilities are assessed through five different criteria, according to Amartya Sen: how important real freedoms are to determining social advantages, the ability to be productive with available resources; how likely it is that their activities will bring happiness; balancing material and non-material things when discussing one's welfare, and how evenly distributed societal opportunities are. This deals primarily with human development in nations around the world; the higher these capabilities are, the more developed the nation is. This is often related closely to poverty, as the more poverty-stricken you are, the fewer capabilities you have to succeed.
Many of these philosophies have very similar principles; for instance, social contract theory is closely tied in with classical liberalism, as they have unique focuses on the individual and their relationship with authority and societal figures. Contrast that with communitarianism and the capabilities approach, however, and you get distinct differences; the latter two philosophies emphasize the role of society in improving conditions for the poor and behaving as a community that helps each other. Marxism also relates closely to communitarianism, as the individuals of a society are seen as equal and deserving of welfare. This flies in the face of libertarianism and the social contract theory, which posits a rough truce between individuals, and the focus on self-interest as a means to help the whole of society.
This dichotomy is at the heart of Western political philosophy, as the debate rages between whether or not we should expend our individual resources to help those less fortunate. I personally find communitarianism the preferable philosophy of these options, as it emphasizes a communal sense of welfare and concern for one's fellow man. While libertarianism claims that self-interest is king, there are certain economic and social inequalities that are institutionalized, and not everyone starts out on a level playing field. As we are incredibly interrelated with regards to how we communicate and help each other, that level of self-interest seems to be counterproductive.
Moore, B.N, Bruder, K. (2010). Philosophy: the power of ideas. 8th ed. McGraw-Hill College.