Knowing and Trusting: The Medieval Social Epistemologies of Augustine and Aquinas by Matthew Kent Siebert A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Department of Philosophy University of Toronto 2014 © Copyright by Matthew Kent Siebert, 2014 Knowing and Trusting The Medieval Social Epistemologies of Augustine and Aquinas Matthew Kent Siebert Doctor of Philosophy Department of Philosophy University of Toronto 2014 Abstract This dissertation is an introductory exploration of two influential medieval thinkers, Augustine and Aquinas, on the topic of testimony. I explain how Augustine’s view that testimony is a source of knowledge (notitia) developed through four stages, and argue that on Augustine’s view testimonial belief is justified inferentially. I argue that Aquinas thinks some testimonial belief is justified inferentially, and some is justified by adhering to the speaker as the formal object of one’s belief, on the grounds that the speaker is truthful. I argue that these provide knowledge when they provide cognitio. And I argue that Aquinas’s view can be developed into a plausible account of testimonial trust and trustworthiness. ii Acknowledgments I am extremely grateful for the guidance and support of Peter King, Martin Pickavé, and Jennifer Nagel in the writing of this dissertation. I am also grateful to Deborah Black, Michael Siebert, Simona Vucu, and Ian Drummond, for their very helpful comments on earlier drafts of some of these chapters. And I am grateful to the Social Sciences and Humanities Research Council of Canada, the Government of Ontario, and the University of Toronto for financial support. iii Table of Contents Introduction 1 0.1 How Testimony Works: The Basics 2 0.2 Testimony and Knowledge 5 0.3 Testimony and Trust 7 0.4 Summary 7 0.5 Difficulties and Rewards of this Dissertation 7 Chapter 1. Augustine’s Development on Testimony: From Opinion to Knowledge 1.0 Introduction 9 1.1 Platonic and Stoic Elements 11 1.2 Stage 1: Platonist 19 1.3 Stage 2: Particularist 24 1.4 Stage 3: Ordinary Language 38 1.5 Against Alternative Explanations of Augustine’s Shift 55 1.6 Stage 4: Compromise 59 1.7 Conclusion 75 Chapter 2. Augustine on Testimonial Knowledge 2.0 Introduction 77 2.1 Problems of the Default Interpretation 79 2.2 Conditions on Testimonial Knowledge 83 iv 2.3 Belief on Authority 91 2.4 The Inferential Interpretation 105 2.5 Two Objections and a Puzzle 116 2.6 Conclusion 119 Chapter 3. Aquinas on Testimonial Opinion and Testimonial Faith 3.0 Introduction 120 3.1 Faith as Assent about the Unseen 129 3.2 Testimonial Opinion 134 3.3 Testimonial Faith 143 3.4 Presumption 156 3.5 Conclusion 159 Chapter 4. Aquinas on Knowledge and Testimony 4.0 Introduction 162 4.1 Cognitio 166 4.1.1 Cognitio defined 166 4.1.2 Cognitio’s factivity 173 4.1.3 Cognitio’s epistemic force 174 4.1.4 Ordinary knowledge is cognitio 182 4.2 Objections 183 4.2.1 False Cognitio 184 4.2.2 Cognitio seems too low-level 189 4.3 Testimonial Cognitio 194 v 4.3.1 General Considerations 194 4.3.2 Knowledge from Testimonial Opinion 197 4.3.3 Knowledge from Testimonial Faith 199 4.4 Conclusions 206 Appendix A 207 Chapter 5. Testimonial Trust and Trustworthiness 5.0 Introduction 213 5.1 Three Recent Accounts 215 5.2 An Aristotelian Alternative 220 5.3 Two Worries about the Aristotelian Account 229 5.4 Testimonial Trust and Judging Truthfulness 233 5.5 The Epistemic Advantage of Trust 237 5.6 Conclusion 240 Conclusion 6.0 Introduction 241 6.1 Is Testimony a Source of Knowledge? 241 6.2 What Kind of Knowledge Can One Get from Testimony? 245 6.3 How is Testimonial Knowledge (or Belief) Acquired? 246 6.4 How does Testimonial Trust Work? 249 Works Cited 7.1 Primary Texts by Augustine 254 7.2 Primary Texts by Aquinas 258 vi 7.3 Other Medieval or Scholastic Primary Texts 261 7.4 Early Modern Primary Texts Cited 263 7.5 Secondary Works Cited 264 vii Introduction In epistemology, ‘testimony’ refers to the practice of believing on the say-so of others. Testimony is incredibly important. Without it, you wouldn’t know about anything outside your experience. You wouldn’t know about events in Syria, or world events generally. You wouldn’t know anything about the middle ages, or other historical periods. You probably wouldn’t have friends, because you wouldn’t be able to find out what anyone thought of you, or let others know what you think of them. You wouldn’t even know who your own parents are, since you don’t remember your birth. It would be the end of human society. Testimony is fundamental. This dissertation is an introductory exploration of medieval social epistemology, a topic that has been almost completely neglected. The study is focused on two pivotal medieval thinkers, Augustine and Aquinas, and is focused on their epistemology of testimony. If we can understand their interests, their terms, and the positions they take on issues concerning testimony, we will be in a good position to understand what other medieval thinkers in the Latin tradition, and later philosophers influenced by that tradition, had to say on issues of social epistemology. This will put us in a position to draw new insights into social epistemology from Augustine, Aquinas, and other medievals. Augustine (354-430) is an appropriate starting point, as he seems to have been the first philosopher in the West to argue that we can have knowledge from testimony. He consciously broke with the schools of ancient philosophy on this topic, and this made his defense of testimonial knowledge a real turning point in the history of philosophy. And looking ahead, Augustine was extremely influential in the Latin philosophical tradition. Many passages from his writings, including some key texts about testimony, found their way into Peter Lombard’s Sentences, which for centuries was a required text for medieval scholastics. So it is important to 1 get his view right. A very few brief and tentative studies have been made of Augustine on testimonial knowledge;1 the present study is more thorough. In this introductory work, I will draw the trajectory of medieval social epistemology with a broad stroke, beginning with Augustine. An appropriate second point is Thomas Aquinas (1225-1274). Aquinas arrives on the scene when translations of Aristotle and of Aristotelian commentators had become fairly well known, and the state of debate on issues relevant to the epistemology of testimony was neither formless nor rigidly ramified, but well under way. The terms and contexts within which Aquinas developed his ideas on testimony were common to most of the scholastics after him. His works were frequently criticized or defended by scholastics in the century after his death, and frequently commented on by scholastics of the Renaissance and later. So a study of Aquinas on testimonial knowledge opens a door to understanding much of the history of social epistemology. I indicate how in some more detail in the Conclusion. 0.1 How Testimony Works: The Basics Let’s start by getting a bit clearer on what testimony is. Most epistemologists today agree that testimonial knowledge can be narrowed down to a subset of the knowledge we gain from certain speech acts, either assertions generally or tellings in particular.2 For example, I could give testimony to my mother that it is raining outside my window by telling her over the phone that it is raining outside my window. Arguably, in such cases the speaker who tells someone that p presents herself to that person as knowing that p. Now, since our concern is with testimony as its own knowledge source, we should distinguish knowledge that is testimonially based from other kinds of knowledge merely prompted by testimony. Suppose upon meeting you I tell you that I 1 I have in mind King and Ballantyne (2009) as well as passages from Coady (1992: chap. 1), and McMyler (2011: chap. 1). 2 Fricker (1995: 397) says that ‘tellings generally’ are the relevant category. But others distinguish tellings from ‘mere’ or ‘bare’ assertions, arguing that tellings provide a special reason to believe that mere assertions do not. See Hinchman (2005), Moran (2005b), Fricker (2006), and Zagzebski (2012: chap. 6) for various ways to draw this distinction. Graham (2000) focuses on ‘perceptual reports’. Lackey (2008: 39, cf. chap. 1) prefers to focus on ‘statements’ or ‘acts of communication’. 2 am happy by singing “I’m happy!” in a baritone voice, and you astutely infer from my singing that I sing baritone. Your knowledge that I sing baritone in this case is not testimonially based, since it is not in virtue of the content of my telling you that I am happy that you know that.3 Or suppose that you are staring blankly out a window and I say “That’s a blue jay!”, thereby prompting you to notice for yourself that the bird just outside the window is a blue jay. Having your attention drawn to something by testimony, which you then know by some non-testimonial means (in this case, sense perception) does not make your knowledge testimonially based.4 (This distinction will be important for understanding some key passages in Augustine.) Nailing down testimony as a source of knowledge any further is tricky, in part because there is a vibrant debate about how testimony works. Three major schools of thought on the justification of testimonial belief have recently emerged, which I call the Default, Reductive, and Assurance views.5 On the Default view, when someone says that p, all the audience requires for being justified in believing that p is that the audience not have any defeaters for believing p.6 On this view, the testimony of others is a sui generis ‘rational source’, analogous to but not reducible to other rational sources like memory, perception, and inference.