In order to more clearly conceptualize Western philosophy’s territory, let’s consider it in relation to two other powerful cultural forces with which it’s intertwined: religion and science. We may (roughly) characterize the contrast between philosophy and religion as follows: philosophy relies on reason, evidence, and experience for its truths; religion depends on faith, authority, grace and revelation for truth. Of course, any philosophical position probably contains some element of faith, inasmuch as reasoning rarely gives conclusive proof; and religious beliefs often contain some rational support, since few religious persons rely completely on faith.
The problem of the demarcation between the two is made more difficult by the fact that different philosophies and religions—and philosophers and religious persons within similar traditions—place dissimilar emphasis on the role of rational argument. For example, Eastern religions traditionally place less emphasis on the role of rational arguments than do Western religions, and in the east philosophy and religion are virtually indistinguishable. In addition, individuals in a given tradition differ in the emphasis they place on the relative importance of reason and faith. So the difference between philosophy and religion is one of emphasis and degree.
Still, we reiterate what we said above: religion is that part of the human experience whose beliefs and practices rely significantly on faith, grace, authority, or revelation. Philosophy gives little if any, place to these parts of human experience. While religion generally stresses faith and trust, philosophy honors reason and doubt.
Distinguishing philosophy from science is equally difficult because many of the questions vital to philosophers—like the cause and origin of the universe or a conception of human nature—increasingly have been taken over by cosmologists, astrophysicists, and biologists. Perhaps methodology best distinguishes the two, since philosophy relies on argument and analysis rather than empirical observation and experiment. In this way, philosophy resembles theoretical mathematics more than the natural sciences. Still, philosophers utilize evidence derived from the sciences to reformulate their theories.
Remember also that, until the nineteenth century, virtually every prominent philosopher in the history of western civilization was either a scientist or mathematician. In general, we contend that science explores areas where a generally accepted body of information and methodology directs research involved with unanswered scientific questions. Philosophers explore philosophical questions without a generally accepted body of information
Philosophical analysis also ponders the future relationship between these domains. Since the seventeenth-century scientific revolution, science has increasingly expropriated territory once the exclusive province of both philosophy and religion. Will the relentless march of science continue to fill the gaps in human knowledge, leaving less room for the poetic, the mystical, the religious, and the philosophical? Will religion and philosophy be archaic, antiquated, obsolete, and outdated? Or will there always be questions of meaning and purposes that can never be grasped by science?
Bertrand Russell (1872-1970), one of the twentieth century’s greatest philosophers, elucidated the relationship between these three domains like this: “All definite knowledge … belongs to science; all dogma as to what surpasses definite knowledge belongs to theology. But between theology and science there is a no man’s land, exposed to attack from both sides; this no man’s land is philosophy.”