epistemology Modern philosophyphilosophy

Although modern philosophers as a group are usually thought to be purely secular thinkers, in fact nothing could be further from the truth. From the early 17th century until the middle of the 18th century, all the great philosophers incorporated substantial religious elements into their work. In his Meditations (1641), for example, Descartes offered two distinct proofs of the existence of God and asserted that no one who does not have a rationally well-founded belief in God can have knowledge in the proper sense of the term. Benedict de Spinoza (1632–77) began his Ethics (1677) with a proof of God’s existence and then discussed at length its implications for understanding all reality. And George Berkeley (1685–1753) explained the apparent stability of the sensible world by appealing to God’s constant thought of it.

Among the reasons modern philosophers are mistakenly thought to be primarily secular thinkers is that many of their epistemological principles, including some that were designed to defend religion, were later interpreted as subverting the rationality of religious belief. The views of Thomas Hobbes (1588–1679) might briefly be considered in this connection. In contrast to the standard view of the Middle Ages that propositions of faith are rational, Hobbes argued that such propositions belong not to the intellect but to the will. The significance of religious propositions, in other words, lies not in what they say but in how they are used. To profess a religious proposition is not to assert a factual claim about the world, which may then be supported or refuted with reasons, but merely to give praise and honour to God and to obey the commands of lawful religious authorities. Indeed, one does not even need to understand the meanings of the words in the proposition in order for this function to be fulfilled: simply mouthing them would be sufficient.

In An Essay Concerning Human Understanding (1690), Locke further eroded the intellectual status of religious propositions by making them subordinate to reason in several respects. First, reason can restrict the possible content of propositions allegedly revealed by God; in particular, no proposition of faith can be a contradiction. Furthermore, because no revelation can contain an idea not derived from sense experience, we should not believe St. Paul when he speaks of experiencing things as “eye hath not seen, nor ear heard, nor hath it entered into the heart of man to conceive.…” Another respect in which reason takes precedence over faith is that knowledge based on immediate sense experience (what Locke calls “intuitive knowledge”) is always more certain than any alleged revelation. Thus, a person who sees that someone is dead cannot have it revealed to him that that person is at that moment alive. Rational proofs in mathematics and science also cannot be controverted by divine revelation. The interior angles of a rectangle equal 360°, and no alleged revelation to the contrary is credible. In short, says Locke, “Nothing that is contrary to, and inconsistent with, the clear and self-evident dictates of reason, has a right to be urged or assented to as a matter of faith.”

What space, then, does faith occupy in the mansion of human beliefs? According to Locke, it shares a room with probable truths, which are propositions of which reason cannot be certain. There are two types of probable truth: that which concerns observable matters of fact, and that which goes “beyond the discovery of our sense.” Religious propositions can belong to either category, as can empirical and scientific propositions. Thus the propositions “Caesar crossed the Rubicon” and “Jesus walked on water” belong to the first category, because they make claims about events that would be observable if they occurred; on the other hand, propositions like “Heat is caused by the friction of imperceptibly small bodies” and “Angels exist” belong to the second category, because they concern entities that by definition cannot be objects of sense experience.

Although it might seem that Locke’s mixing of religious and scientific claims helped to secure a place for the former, in fact it did not. For Locke also held that “reason must judge” whether or not something is a revelation and more generally that “Reason must be our last judge and guide in everything.” Although this maxim was intended to reconcile reason and revelation—indeed, he calls reason “natural revelation” and revelation “natural reason enlarged by a new set of discoveries communicated by God”—over the course of 200 years reason repeatedly judged that alleged revelations had no scientific or intellectual standing.

Despite the strong religious elements in the thought of modern philosophers, especially those writing before the middle of the 18th century, contemporary epistemologists have been interested only in the purely secular aspects of their work. Accordingly, these aspects will predominate in the following discussion.