Matthew Siebert

We tend to think that science depends not on faith, but on what has been verified empirically. But according to Aquinas, a kind of faith is necessary for (a) scientific discovery, (b) distribution of scientific knowledge from specialists to the rest of the scientific community, and (c) passing established science on to learners. Even though our understanding of science has developed considerably over the centuries, Aquinas’s framework could be useful for a better understanding of social knowledge in modern science.

Believing someone is, as Elizabeth Anscombe said, “trusting him for the truth.” Recent accounts of how we trust speakers for the truth have given a central role to speaker trustworthiness but have said little about what speaker trustworthiness is. I argue that it is best to think of speaker trustworthiness as the virtue of truthfulness. I give an account of truthfulness, show how that account solves problems for other accounts of speaker trustworthiness, and then use my account to explain the epistemic benefits of trusting a truthful speaker.

According to David Hume, testimonial belief is justified inferentially; according to Thomas Reid, by contrast, testimonial belief has justification by default. Aquinas’s approach is different. This article explains the importance of various kinds of testimonial belief in Aquinas, and argues that his account of testimonial justification is a pluralist one: testimonial ‘opinion’ is justified inferentially, while testimonial ‘faith’ is justified by one’s attitude toward the speaker. When one has faith in this restricted sense, one believes the speaker’s statement in order to ‘adhere’ to the speaker, with a special act of will, and typically for the reason that the speaker is truthful. The article concludes with some comments on the characteristics and advantages of Aquinas’s account that distinguish it from recent accounts of testimonial justification.

Aquinas says that faith is belief about things one does not “see” for oneself. But if you do not see it for yourself, what makes your belief reasonable? Recent interpreters have missed a key part of Aquinas’s answer, namely, that faith is believing God (credere Deo). In other words, they have not given sufficient attention to the formal object of faith. As a result, they overemphasize other parts of his answer. Drawing partly on recent epistemology of testimony, I explain how the formal object of faith contributes to the justification of one’s faith.

“eyes are surer witnesses than ears,” says Heraclitus, deploying the term ‘witnesses’ metaphorically to steer us toward what we can see for ourselves, and away from depending literally on the witness of others.1 Much ancient epistemology leans the same way. The tendency from pre-Socratic times on is to distinguish between doxa and epistêmê, and to say that ordinary human testimony on its own can give us no more than doxa.2 Some ancient philosophers have what we might call ‘rationalist’ reasons for not recognizing testimonially based knowledge: for them knowledge requires intellectual insight into some truth.3 Others have ‘empiricist’ reasons: for them, one’s knowledge must ultimately trace...