Religion is an extremely diverse collection of human practices, beliefs and values. It is the source of some of history’s most powerful art and architecture, music and dance, and of many other cultural productions that have endured over the ages. Religions try to answer questions that science cannot: the ultimate meaning of life, the origin of the universe, and so on. They may be very large-scale and coherently organized with a clear hierarchy (as in Roman Catholicism, with its center at the Vatican and a system of cardinals, bishops, priests, lay people, and male religious orders; or as in Islam, with a complex network of Islamic societies). Alternatively, they may be small-scale and loosely organized, with no clear hierarchies at all, as in Hinduism or Buddhism.
It is hard to give a single definition of religion because the concept has so many different uses in social thought. Some philosophers have tried to define it substantively, seeking a set of characteristics that all religions share. Others have sought to define it functionally, looking at the ways in which religions are related to one another.
The functional approach has a long tradition in philosophical thinking about religion. Durkheim’s Elementary Forms of the Religious Life exemplifies it, though in his later years he rejected its categorical nature as a way of understanding religion (Dobbelaere and Lauwers 1973). More recently, thinkers who would not normally be classified as philosophers of religion have taken up these issues, such as Martin Heidegger (1904-1976), Jean-Paul Sartre (1805-1980) and Simone de Beauvoir (1909-1943).
In this context, some philosophers have taken a verstehen approach to definition, searching for understandings within particular social worlds rather than trying to find general principles that apply everywhere. This is implicit in ethnographic and participant-observation research methodologies, for example. It is also a key element of the religious studies movement, founded by Max Weber (1864-1920) and others.
Some of the most important recent developments in philosophy of religion have been a result of the rise of social sciences such as history, archaeology and anthropology. These disciplines have provided for the first time systematic knowledge of world cultures and the religions they practised. This, combined with the rise of philosophy in its Continental forms, has given the study of religion a fresh impetus.
As a result of these developments, it is now common to see scholars use a polythetic or prototype approach to the idea of religion. In this approach, a definition of religion is defined as the set of characteristics that make up what we might call the “family resemblances” of different religions. These family resemblances do not necessarily include all of the beliefs, practices and value systems that could possibly be described as part of a religion, but they do have enough of the right characteristics to be considered a religion. These polythetic approaches to the concept of religion have been criticized for their lack of rigorous logical analysis and their inability to account for the uniqueness of individual cases.