O’Brien, D. 2016. An Introduction to the Theory of Knowledge, 2nd revised edition. Oxford: Polity. 224 pp. ISBN: 978-0745664316.
One of the most profuse areas in philosophy, with continuous developments, is the theory of knowledge. Since the end of the twentieth century, but especially in the last twenty years, the emergence in the market of books on epistemology has not stopped growing. It is therefore pleasing to find, among the many introductory works to the theory of knowledge, a book as attractive, accessible and updated as that of Dan O’Brien.
In his previous book, an edited volume of Hume’s writings on religion, Bloomsbury Companion to Hume (2015), he was devoted to one of his current research interests, David Hume. Other research interests include the epistemology of testimony and trust.
This recent book, An Introduction to the Theory of Knowledge is an extensively revised second edition with expanded sections on several core issues in epistemology. Amongst the topics discussed by O’Brien are classics problems as scepticism and justification, but also contemporary debates concerning epistemic luck, social epistemology, contextualism, and new sections such as the lottery paradox and virtue epistemology. There are 16 chapters with another unnumbered chapter (preface).
The book is divided into five parts: Chapters 1 and 2 together make up Part I (“Introduction to Knowledge”) of the book, which is mostly devoted to a positive and constructive presentation of the theory of knowledge. Part II (“Sources of Knowledge”) comprises chapters 3 to 5 and critically delineates different strands of knowledge and the way we might acquire a priori knowledge by reasoning (chapter 3), and empirical knowledge by perceiving the world (chapter 4) or by testimony (chapter 5). Chapters 6 to 8, together making up Part III, are about the problem of justification. On the one hand, the debate relating to the source of epistemic justification is explored and, on the other, the debate between internalism and externalism. After having discussed the sources of knowledge and the structure and nature of justification, in Part IV (“Scepticism”, chapters 9 to 12), the author turns to scepticism with the inclusion of expanded sections as contextualism. Chapters 13 to 16 together make up the final part V (“Areas of Knowledge”) of the book in which O’Brien examines our alleged knowledge of the past, other minds, moral knowledge, and God. Besides, the book includes a glossary and a bibliography.
I will now proceed to give an outline of the chapters each with a summary of the most important themes and main theses. After that, there will be a critical evaluation of the approach presented in the book.
Part I of “An Introduction to the Theory of Knowledge” sketches the contemporary background of the definition of knowledge and the differences between three kinds of knowledge: factual knowledge, ‘ability knowledge’ and knowledge by acquaintance. These are central to the contemporary debate since factual knowledge is largely characterized by its opposition to ability or practical knowledge. O’Brien introduces two further approaches to the definition of knowledge: “knowledge first” (Williamson 2000) and Wittgenstein’s family resemblance.
In the third chapter, where Part II begins, O’Brien elaborates on some example questions regarding a priori knowledge and distinguishes that kind of knowledge from two other sources such as experience and testimony. Perception, testimony and justification are investigated in regard of how they ground knowledge, knowledge that we allegedly have. He questions the traditional claims that a priori knowledge is certain and self-evident, and he explores in what measure the issue of innateness is problematic.
Chapter 4 presents a variety of empirical positions diverging from a priori knowledge and considers how our experiences perceptually fit into place with the world in a variety of ways. It examines metaphysical issues concerning the nature of the objects involved in perception. On the indirect realist approach, perceptual knowledge generates a problem stemming from the argument from illusion, that is, direct experience of the world is impossible. In opposition to that, there are idealists approaches or theories that deny that sense data are involved in perception as some intentionalist theories of perception claim (adverbialism or intentionalism approaches). Intentionalists emphasize certain parallels between perceptual experience and beliefs as representations of the world. Thus, the intentionalist claims that perception also involves representational states and that intentional content represents the state of the independent external world but without an ontological commitment to non-material mental objects. There are several problems to representational accounts of perception that O’Brien analyses in this chapter.
Chapter 5 is dedicated, acutely and profoundly, to what O’Brien takes to be the other source of empirical knowledge. By testimony, we can acquire empirical knowledge from others without having perceived the relevant facts ourselves. For some philosophers, testimony is reducible to one of the other two types of knowledge that are considered basic (a priori knowledge and perception). As an alternative to this conception—that the author calls ‘individualistic’ approach to knowledge because: “It is the solitary individual that is the locus of epistemology, either acquiring knowledge through a priori reasoning or through empirical reasoning grounded in perception” —, O’Brien accepts that we can acquire justified beliefs and knowledge from testimony that is not reducible to the other types of knowledge. In other words, he questions the contention that testimonial beliefs are second rate and dedicates an entire chapter to the current debate on this topic.
After having looked at three sources of knowledge—a priori, perception and testimony—in chapter six, the central Part III of the book, O’Brien begins to focus on the key notion of justification. First, the epistemic sense of ‘justification’ is distinguished from certain other uses of the term, for example, pragmatic justification as opposed to epistemic justification. In full coherence with the primacy of factual knowledge displayed in Part I, O’Brien points out that there is no further justification than epistemic justification, that is, a belief is epistemically justified if we have good reasons to think that it is true. Then, he reinforces the relevance of the concept of justificatory foundations for all our empirical beliefs. In this case, perceptual experience of the world grounds our beliefs and, accordingly, foundationalism is presented as a response to an infinite regress of justification. Chapter 7 tries to deny this kind of justification from a coherentist approach. In a coherentist theory of justification, the crucial point is that our belief system must not contain contradictory beliefs, but there are two problems with this kind of justification that O’Brien presents and analyses: Firstly, if we want to know the world, it is not clear how coherence can justify that knowledge. Secondly, in case two alternative belief systems are equally coherent, which one is justified or are both of them justified alike?
Next, in chapter 8, the debate between internalism and externalism is examined. First, the author proposes an internalist view: considering knowledge as justified true belief. To justify a belief, we must be capable of reflecting on our reasons to believe. In this way, internalists emphasize the subjective approach, that is, the justification for a thinker’s beliefs must be cognitively accessible to him or her. Then, he develops the externalist view, characterized by a rejection of the internalist approach, claiming that to justify our knowledge, we do not need to be able to reflect upon what it is that justifies our beliefs. Instead, externalists focus on objective questions that allow distinguishing knowledge from true belief. O’Brien analyses different externalist theories such as causal, reliabilist accounts of knowledge and Nozick’s account. Nevertheless, as the author points out internalism and externalism are two conceptions of knowledge appropriate for distinct epistemological questions and projects.
The next part of the book, Part IV, investigates sceptical concerns. O’Brien discusses local and global scepticism and the possibility of a different kind of empirical justification. In chapter 9, more than one sceptical argument is presented that threaten all our claims to knowledge based on Cartesian scepticism. There are positive arguments such as Descartes’ arguments that might have conclusions which employ a refutation of scepticism. But, as O’Brien explains, a Cartesian refutation of scepticism is not persuasive for most philosophers.
In the first part of the book, O’Brien focused on different forms of invariantism: that is, epistemological theories that work with a single set of standards, those that all claims to knowledge must meet. Then, in chapter 10, he presents a recent approach that has questioned invariantism: the “contextualist” approach in response to scepticism. According to contextualism, the standards that beliefs must meet to be classified as knowledge differ between contexts. O’Brien analyses how contextualists attempt to resolve the lottery paradox, the Cartesian scepticism and also discusses the problems undermining contextualism. In this part, he considers two forms of invariantism: that is, Williamson’s non-sceptical invariantism and Stanley’s interest-relative invariantism.
In chapter 11, he continues addressing Hume’s inductive scepticism. The knowledge of the unobserved is analysed and Hume’s argument is offered. According to Hume, we should not worry about providing a philosophical explanation of how our empirical thinking can be justified, since it cannot, so we should devote ourselves to the scientific task of providing a causal explanation of how we have the beliefs we have. In chapter 12, this strategy is presented as the modern project of naturalized epistemology.
In chapter 13, O’Brien examines the epistemic problem of the experience of the past in the present. He argues against an indirect realist account of memory, presents the causal theory of memory and issues related to scepticism.
In the final chapters of the book O’Brien examines some other areas of knowledge: In chapter 14, knowledge of other minds, and chapter 15 and 16, moral knowledge, and God.
I would like to point out some shortcomings or aspects that I have missed in this introduction and that I think would be useful to consider.
Firstly, maybe it is worth to dedicate some space to an analysis of ordinary or pre-scientific knowledge. Ordinary knowledge allows us to grasp a series of truths—even metaphysical (the principle of non-contradiction or causality) and moral (do good and avoid evil) — immediately or in a pre-scientific way. Pre-scientific knowledge can be manifested through other channels that are also a source of truth for people, such as art, literature or poetry. These aspects of culture can reveal, for example, what is a human being with similar depth and concreteness as philosophy does. In this way, there is a certain immediate knowledge that also provides a non-systematic, imprecise and imperfect knowledge that demands a critical or scientific reflection. Philosophers have characterized this kind of knowledge in different ways. For example, Polanyi (1958) maintains that there are two kinds of human knowledge: explicit and tacit knowledge. The tacit dimension is pre-articulated; when we know that our explicit knowledge is true, we know it tacitly. This pre-scientific or firsthand knowledge (Sosa 2019) is necessary to guide us in everyday life. In any case, ordinary, tacit, firsthand or pre-scientific knowledge is another manifestation of human rationality to consider.
Secondly, as O’Brien explains in Part I, there are other approaches to knowledge, for example, knowledge as factive mental state. Even though he presents this other definition of knowledge, the strengths of this kind of definition are not considered in the last part of the book. In fact, Williamson (2000) argues that defining knowledge as a function of the variables ‘belief’ and ‘truth’ that must be analysed in internal and external components, means admitting dualism at its base (Williamson 2000, 21). Conversely, knowledge is not a metaphysical hybrid, formed partly by mental components (‘justified belief’), partly by the world (‘truth’), but is entirely a factual, epistemically basic mental state. The strength of this alternative definition of knowledge as a mental state whose content depends constitutively on the world is that it avoids both a mind-world dualism and the problem of scepticism (that it is generated by assuming a notion of knowledge as a non-factual mental state). It is the feasibility of human knowledge that makes it unnecessary to postulate true belief, which constitutes a cross between mind and world.
Thirdly, O’Brien examines the epistemic issue of the memory and devotes a study to the problem of the experience of the past in the present. Nowadays, the topic of memory is investigated form a variety of perspectives. Whilst the author investigates the epistemic relationships between perception, testimony, and memory, the current debate opens the opportunity to think also about the distinction between memory and imagination, collective memory or situated, embedded, and extended memory.
Moreover, although the book devotes too, an extensive study to the problem of induction, it hardly considers that of deduction or inference and justification of inferences, that is, the problem of justification of logical knowledge. In recent years, a philosophical reflection of the justification of logic has been dominated by the problem of circularity and infinite regresses. How can we justify logical laws in a way that doesn’t rely on those laws? In general, to justify the logical rules inferentially involves using logical principles, which generates circularity. Paul Boghossian (2000, 245–254; 2001, 23–29) has argued that the only way to justify the basic logical principles is to claim a rule-circular justification, according to which knowledge of the validity of the basic rules of inference is the result or product of inferences. Boghossian considers the apriority of logical propositions from an approach based on meaning, more explicitly, from theories that defend that a better understanding of conceptual meaning helps to explain the justification of beliefs or the transition between beliefs of a person. In this sense, he assumes that the principles of logic, as theoretical principles, are part of the meaning of language expressions.
Finally, I would like to highlight another source of knowledge, affective knowledge, which has been often neglected. Affective knowledge is a form of apprehension of reality experimentally, intuitively and impregnated with affective data, which precedes and accompanies acts of reason and acts of will. This affective knowledge can also be directed towards other people and has been treated by phenomenology in the so-called empathic knowledge or empathy. It is a kind of relationship with other minds or reality of the others in such a way that we can intuitively foresee the intentions or emotions of those people to whom we are linked by affective ties. To feel compassion, for example, means to suffer some pain with the other as if we were the ones who suffer the pain. So, there is a certain influence of the affects on knowledge; we refer to that form of apprehension of reality as treated by classical philosophy, called connatural knowledge. It is worth debating if, in some sense, it could be similar to knowledge by acquaintance. Human beings can know truths in a non-discursive or argumentative way by knowledge through connaturality: the just person knows connaturally recognize the right good that must be done, without having to make excessively complex reasoning; a person can recognize a face he or she knows—this facial recognition is not simply knowledge of the body, but knowledge enacted through the body.
In Personal Knowledge, Polanyi (1962, part II, chapter 5, §5) highlights this dimension of corporality. When we know something, this knowledge takes on our whole person. For example, when you feel a disgust, this disgust could be intended as a kind of connatural or embodied judgment. In this sense, the embodiment is a feature of Polanyi’s tacit knowledge. There are other cases, for instance, the position of your limbs and certain bodily movements that you know without observation (Anscombe 1963, 15). So, if the body is expressive and intentional in the spirit of Merleau Ponty (1945), we are sensibly attuned to our environment through a connatural or embodied knowledge: “When I say that I have senses and that they give me access to the world, I am not the victim of a confusion, nor do I mix up causal thought and reflection. I merely express the truth that forces itself upon a complete reflection, namely, that I am capable (through connaturality) of finding a sense in certain aspects of being, without myself having given them this sense through a constitutive operation” (Merleau-Ponty 1945, 225). These different kinds of connatural or embodied knowledge are worth to be explored.
Lately, there have been many studies on emotional intelligence and the philosophy of emotions (Barrett 2017, Brady 2013, Damasio 1994, Goleman 2006, Solomon 2010). Certainly, the interest in the knowledge of ourselves, our knowledge of other persons, and the relationship between them has been growing in recent years: what are the roles of emotion in knowing ourselves and others? And what are the role of emotion in regulating social interaction between humans? These questions may be approached from relatively diverse perspectives.
O’Brien explains through testimony or belief how a person knows to enter into a personal relationship with another person. Testimony provides knowledge (although, like all human knowledge, it is fallible) because it tells us about the state of things. We believe in the existence of Higgs bosons because we trust in Higgs’ scientific research, and not because we have personally experienced it. Accepting the testimony of others presupposes an act of freedom: the testimony of the other person is accepted thanks to the trust that is granted. Trust is, from my point of view, the anthropological basis of many cognitive acts. It is an everyday experience without which we could not live; furthermore, in the life of humans the transmitted knowledge, in which we simply trust, are much more numerous than those acquired through personal verification. Although error is possible (by deceit or ignorance of the one to whom we have confided) this does not invalidate this kind of rationality. It would be quite irrational to aim for personal observations for each of our daily beliefs, simply for the desire to be safe and to find guarantees of everything. Trust in others frees us from the enormous burden of possessing personal evidence: we could not progress if we did not trust.
Despite these omissions, the book is a great achievement: it offers an introduction to classical and contemporary epistemology and it delivers a theoretical and practical guide through the field. As a general point, readers may not buy into every argument of the book and every line of thought presented by O’Brien; still, the main goal is to introduce a non-specialized audience to complex epistemological problems such as those concerning the private language argument or non-conceptual content. This objective has been achieved.
The study of the book is especially recommended for those who seek to question their own presumptions and for students who are new to the subject. In teaching introductory undergraduate modules, the book or its chapters may serve as a basis for discussion with supplementation of other texts.
All in all, the book is engaging and accessible. It helps us to see that many of our problems about knowledge arise from trying to fit everything into a single explanatory template, rather than realising that several epistemological topics can be understood from irreconcilable and irreducibly different points of view.
I thank Markus Schrenk and Isabelle Keßels for their careful reading of this review and their helpful hints. Thanks, as well for their insightful comments and their linguistic suggestions.
Boghossian, P. 2000. Knowledge of Logic. In: Boghossian, P. & Peacocke, C. (eds.), New Essays on the A Priori. Oxford: Clarendon Press, 229–254.
Boghossian, P. 2001. How are objective epistemic reasons possible? Philosophical Studies 106(1/2) Selected Papers Presented in 2000 at the 74th Annual Meeting of the Pacific Division of the American Philosophical Association (Nov. 2001), 1–40.
Merleau-Ponty, M. 2012. Phenomenology of Perception. Landes, D. A. (tr.). London: Routledge. (Original: Merleau-Ponty, M. 1945. Phénoménologie de la perception. Paris: Gallimard).
Solomon, R. C. 2010. The Philosophy of Emotions. In: Lewis, M., Haviland-Jones, J.M. & Feldman Barrett, L. (eds.), Handbook of Emotions, 3–16. New York: Guilford Press.
Sosa, E. 2019. Firsthand Knowledge and Understanding. In: Grimm, S.R. (ed.), Varieties of Understanding: New Perspectives from Philosophy, Psychology, and Theology. Oxford: Oxford University Press, 109–122.