Philosophy of religion is the rational study of the meaning and justification of fundamental religious claims, particularly about the nature and existence of God (or gods, or the divine).
Philosophy of religion as part of metaphysics
Philosophy of religion was classically regarded as part of metaphysics, after Aristotle, among whose writings was a piece that later editors identified as The Metaphysics. Aristotle there described first causes as one of the subjects of his investigation. For Aristotle, God was the first cause: the unmoved mover. Philosophy of religion as a branch of metaphysics later came to be called natural theology by rationalist philosophers of the 17th and 18th centuries. In the 18th century, philosophers have adopted the term 'philosophy of religion' for the subject, and typically it is regarded as a separate field of specialization, though it is also still treated by some, particularly Catholic philosophers , as a part of metaphysics.
It can be argued that to nearly anyone capable of understanding the issues, it should be clear why considerations of the divine have been regarded as metaphysical. God, according to most conceptions of God as divine, would be in an important category: that of beings different from the rest of the universe. That is, God is typically conceived as not having a body, and the "mind" of the divine is not typically regarded as anything very like an ordinary human mind. Metaphysics, and in particular ontology, is concerned with the most basic categories of existence, those types of existence that cannot be explained as any other type of existence. By taking this view, the very notion of God (the gods, the divine) cannot be reduced to human concepts of mind or body; God is, on such a view, a sui generis entity, an entity in a category all of its own.
This, however, would be to view the content of the philosophy of religion very narrowly. In fact the subject has long involved important questions in areas such as epistemology, philosophy of language, philosophical logic, and moral philosophy (as the following section indicates).
The questions asked in the philosophy of religion
There are a lot of philosophical questions that can be asked about religious beliefs. Two of the significant questions in this field are:
- What is God? That is, what is the meaning of the word 'God'?
- Do we have any good reason to think that God exists, or to think that God does not exist?
Still, there are other questions studied in the philosophy of religion. What, if anything, would give us good reason to believe that a miracle has occurred? What is the relationship between faith and reason? What is the relationship between morality and religion? What is the status of religious language? Does petitionary prayer (sometimes still called impetratory prayer) make sense?
What is God?
The question "What is God?" is sometimes also phrased as "What is the meaning of the word 'God'?" Most philosophers expect some sort of definition as an answer to this question, but they are not content simply to describe the way the word is used: they want to know the essence of what it means to be God. Western philosophers typically concern themselves with the God of monotheistic religions (see the nature of God in Western theology), but discussions also concern themselves with other conceptions of the divine.
Indeed, before attempting a definition of a term it is essential to know what sense of the term is to be defined. In this case, this is particularly important because there are a number of widely different senses of the word 'God'. The term is ambiguous: it is used in different ways by different people. So before we try to answer the question "What is God?" by giving a definition, first we have to get clear on which conception of God we are trying to define. Among those people who believe in supernatural beings, some believe there is just one God (monotheism; see also monotheistic religion), while others, in the greatest numbers Hindus, believe in many different gods (polytheism; see also polytheistic religion). Buddhists generally do not believe in a personal God similar to that of the Abrahamic religions but direct attention to a more undefined state of being called Nirvana.
Within these two broad categories there is a huge variety of possible beliefs, although there are relatively few popular ways of believing. For example, among the monotheists there have been those who believe that the one God is like a watchmaker who wound up the universe and now does not intervene in the universe at all; this view is deism. By contrast, the view that God continues to be active in the universe is called theism. (Note that 'theism' is here used as a narrow and rather technical term, not as a broader term as it is below. For full discussion of these distinct meanings, refer to the article Theism.)
Traditionally philosophers of religion, at least in Europe, were interested in finding out what the word 'God' might refer to, in the sense in which it is used by theists. Again, theism can be defined as the view that exactly one God exists, who is an eternally existent spirit, existing apart from space and time, who has created the universe out of nothing, and is therefore all-powerful; and usually this being is also thought to be all-knowing and all-loving. Even once the word 'God' is defined in this sense, there are still many difficult questions to be asked about what this means. For example, what does it mean for a spirit to create anything? What does 'all-powerful' mean?
Rationality of belief
The second question, "Do we have any good reason to think that God exists, or to think that God does not exist?", is equally important in the philosophy of religion. Since Plato and Aristotle, philosophers and theologians have offered arguments and counterarguments for the existence of God.
Judaism, Christianity, and Islam have all developed religious world views based on, or incorporating, philosophical speculation. There are separate entries on Jewish philosophy, Christian philosophy, and Islamic philosophy.
Major philosophers of religion
See also theology, natural theology, Arguments for the existence of God , arguments against the existence of God, and Major world religions.