Regress Arguments for Foundationalism
A foundational or noninferentially justified belief is one that does not depend on any other beliefs for its justification. According to foundationalism, any justified belief must either be foundational or depend for its justification, ultimately, on foundational beliefs. Historically, foundationalism was very widely, almost universally accepted. Aristotle argued that “not all knowledge is demonstrative” (i.e., not all knowledge is based on an argument from other things known), and that some knowledge must be “independent of demonstration” (Posterior Analytics, I.3). Many of the medieval philosophers seemed in agreement with Aristotle, holding that all knowledge must rest on “first principles” or “self-evident truths” of some sort. More recently, Descartes famously held that all knowledge must rest on a secure foundation of indubitable truths (see the entry on Descartes’s epistemology). Many other philosophers of the early modern period, including Locke, Leibniz, Berkeley, Hume, and Reid, all seemed to accept foundationalism as well, despite disagreeing about much else. When an argument was implicitly or explicitly offered for the view, it was most often some version of the now famous epistemic regress argument. (See Aristotle’s Posterior Analytics, I.3, for an early version of this argument.) Before presenting the argument we should discuss a principle it depends on.
Suppose I claim to be justified in believing that Fred will die shortly and offer as my evidence that Fred has an untreatable and serious form of cancer. Concerned, you ask me how I discovered that Fred has cancer, and I respond that it is just a hunch on my part. As soon as you become convinced (perhaps after further questioning) that I have no good reason to suppose that Fred has cancer, you will immediately conclude that my suspicion about Fred’s condition gives me no justification for believing that Fred will soon die. Generalizing, one might suggest the following principle:
To be justified in believing P on the basis of E one must be justified in believing E.
Now consider another example. Suppose I claim to be justified in believing that Fred will die shortly and offer as my justification that a certain line across his palm (his infamous “lifeline”) is short. Rightly skeptical, you wonder this time what reason I have for believing that palm lines have anything whatsoever to do with length of life. As soon as you become satisfied that I have no justification for supposing that there is any kind of probabilistic connection between the character of this line and Fred’s life, you will again reject my claim to have a justified belief about Fred’s impending demise. That suggests that we might expand our principle to include a second clause.
Principle of Inferential Justification (PIJ):
To be justified in believing P on the basis of E one must be (1) justified in believing E, and (2) justified in believing that E makes probable P.