John Turri

Indicative judgments pertain to what is true. Epistemic modal judgments pertain to what must or might be true relative to a body of information. A standard view is that epistemic modals implicitly quantify over alternative possibilities, or ways things could turn out. On this view, a proposition must be true just in case it is true in all the possibilities consistent with the available information, and a proposition might be true just in case it is true in at least one possibility consistent with the available information. I report three experiments testing this view of epistemic modals. The results show that although modal judgments are sensitive to information about alternative possibilities, the standard quantification theory mischaracterizes the ordinary meaning of modals. I then report two more experiments testing the hypothesis that epistemic modals express willingness to attribute knowledge based on the available information. The results support this hypothesis. The results also show that the difference between “inside” and “outside” probabilistic information, familiar from the judgment and decision-making literature, affects epistemic modal judgments.

Language is a human universal reflecting our deeply social nature. Among its essential functions, language enables us to quickly and efficiently share information. We tell each other that many things are true—that is, we routinely make assertions. Information shared this way plays a critical role in the decisions and plans we make. In Knowledge and the Norm of Assertion, a distinguished philosopher and cognitive scientist investigates the rules or norms that structure our social practice of assertion. Combining evidence from philosophy, psychology, and biology, John Turri shows that knowledge is the central norm of assertion and explains why knowledge plays this role. Concise, comprehensive, non-technical, and thoroughly accessible, this volume quickly brings readers to the cutting edge of a major research program at the intersection of philosophy and science. It presupposes no philosophical or scientific training. It will be of interest to philosophers and scientists, is suitable for use in graduate and undergraduate courses, and will appeal to general readers interested in human nature, social cognition, and communication.

There is a virtual consensus in contemporary epistemology that knowledge must be reliably produced. Everyone, it seems, is a reliabilist about knowledge in that sense. I present and defend two arguments that unreliable knowledge is possible. My first argument proceeds from an observation about the nature of achievements, namely, that achievements can proceed from unreliable abilities. My second argument proceeds from an observation about the epistemic efficacy of explanatory inference, namely, that inference to the best explanation seems to produce knowledge, even if it isn't reliable. I also propose a successor to standard versions of reliabilism, which I call ‘ecumenical reliabilism’. Ecumenical reliabilism is consistent with unreliably produced knowledge and helps explain why unreliably produced knowledge is possible.

Radical skepticism is the view that we know nothing or at least next to nothing. Nearly no one actually believes that skepticism is true. Yet it has remained a serious topic of discussion for millennia and it looms large in popular culture. What explains its persistent and widespread appeal? How does the skeptic get us to doubt what we ordinarily take ourselves to know? I present evidence from two experiments that classic skeptical arguments gain potency from an interaction between two factors. First, people evaluate inferential belief more harshly than perceptual belief. Second, people evaluate inferential belief more harshly when its content is negative (i.e., that something is not the case) than when it is positive (i.e., that something is the case). It just so happens that potent skeptical arguments tend to focus our attention on negative inferential beliefs, and we are especially prone to doubt that such beliefs count as knowledge. That is, our cognitive evaluations are biased against this specific combination of source and content. The skeptic sows seeds of doubt by exploiting this feature of our psychology

Is knowledge justified true belief? Most philosophers believe that the answer is clearly ‘no’, as demonstrated by Gettier cases. But Gettier cases don’t obviously refute the traditional view that knowledge is justified true belief (JTB). There are ways of resisting Gettier cases, at least one of which is partly successful. Nevertheless, when properly understood, Gettier cases point to a flaw in JTB, though it takes some work to appreciate just what it is. The nature of the flaw helps us better understand the nature of knowledge and epistemic justification. I propose a crucial improvement to the traditional view, relying on an intuitive and independently plausible metaphysical distinction pertaining to the manifestation of intellectual powers, which supplements the traditional components of justification, truth and belief.

Many philosophers favour the simple knowledge account of assertion, which says you may assert something only if you know it. The simple account is true but importantly incomplete. I defend a more informative thesis, namely, that you may assert something only if your assertion expresses knowledge. I call this 'the express knowledge account of assertion', which I argue better handles a wider range of cases while at the same time explaining the simple knowledge account's appeal. §1 introduces some new data that a knowledge account of assertion well explains. §2 explains the simple knowledge account's advantage over two of its main competitors. §3 presents a problem for the simple account and offers a solution, which is to adopt the express knowledge account. §4 encapsulates the case for the express knowledge account, and offers a unifying vision for the epistemology of belief and assertion. §5 answers an objection. §6 briefly sums up. Even those who ultimately reject my conclusion can still benefit from the new data presented in §1, and learn an important lesson from the problem discussed in §3, which demonstrates a general constraint on an acceptable account of the norm of assertion.

In this essay I show how to reconcile epistemic invariantism with the knowledge account of assertion. My basic proposal is that we can comfortably combine invariantism with the knowledge account of assertion by endorsing contextualism about speech acts. My demonstration takes place against the backdrop of recent contextualist attempts to usurp the knowledge account of assertion, most notably Keith DeRose's influential argument that the knowledge account of assertion spells doom for invariantism and enables contextualism's ascendancy

In a single-iteration fake barn case, the agent correctly identifies an object of interest on the first try, despite the presence of nearby lookalikes that could have mislead her. In a multiple-iteration fake barn case, the agent first encounters several fakes, misidentifies each of them, and then encounters and correctly identifies a genuine item of interest. Prior work has established that people tend to attribute knowledge in single-iteration fake barn cases, but multiple-iteration cases have not been tested. However, some theorists contend that multiple-iteration cases are more important and will elicit a strong tendency to deny knowledge. Here I report a behavioural experiment investigating knowledge judgments in multiple-iteration fake barn cases. The main finding is that people tend to attribute knowledge in these cases too. Ironically, the results indicate that the presence of fakes could prevent iterated errors from lowering knowledge attributions. The results also provide evidence that ordinary knowledge attributions are based on attributions of cognitive ability.

Philosophers who have written on modesty have largely agreed that it is a virtue, and that it therefore has an important psychological component. Mere modest behavior, it is often argued, is actually false modesty if it is generated by the wrong kind of mental state. The philosophical debate about modesty has largely focused on the question of which kind of mental state—cognitive, motivational, or evaluative—best captures the virtue of modesty. We therefore conducted a series of experiments to see which philosophical account matches the folk concept of modesty. Surprisingly, we found that the folk concept is primarily behavioral. This leads us to argue that modesty may not be a virtue, but that if it is none of the extant philosophical accounts have properly explained why.

What individuates the speech act of prediction? The standard view is that prediction is individuated by the fact that it is the unique speech act that requires future-directed content. We argue against this view and two successor views. We then lay out several other potential strategies for individuating prediction, including the sort of view we favor. We suggest that prediction is individuated normatively and has a special connection to the epistemic standards of expectation. In the process, we advocate some constraints that we think a good theory of prediction should respect.

Many philosophers claim that interesting forms of epistemic evaluation are insensitive to truth in a very specific way. Suppose that two possible agents believe the same proposition based on the same evidence. Either both are justified or neither is; either both have good evidence for holding the belief or neither does. This does not change if, on this particular occasion, it turns out that only one of the two agents has a true belief. Epitomizing this line of thought are thought experiments about radically deceived “brains in vats.” It is widely and uncritically assumed that such a brain is equally justified as its normally embodied human “twin.” This “parity” intuition is the heart of truth-insensitive theories of core epistemological properties such as justification and rationality. Rejecting the parity intuition is considered radical and revisionist. In this paper, I show that exactly the opposite is true. The parity intuition is idiosyncratic and widely rejected. A brain in a vat is not justified and has worse evidence than its normally embodied counterpart. On nearly every ordinary way of evaluating beliefs, a false belief is significantly inferior to a true belief. Of all the evaluations studied here, only blamelessness is truth-insensitive.

What is the relationship between saying ‘I know that Q’ and guaranteeing that Q? John Austin, Roderick Chisholm and Wilfrid Sellars all agreed that there is some important connection, but disagreed over what exactly it was. In this paper I discuss each of their accounts and present a new one of my own. Drawing on speech-act theory and recent research on the epistemic norms of speech acts, I suggest that the relationship is this: by saying ‘I know that Q’, you represent yourself as having the authority to guarantee that Q.

Can judging that an agent blamelessly broke a rule lead us to claim, paradoxically, that no rule was broken at all? Surprisingly, it can. Across seven experiments, we document and explain the phenomenon of excuse validation. We found when an agent blamelessly breaks a rule, it significantly distorts people’s description of the agent’s conduct. Roughly half of people deny that a rule was broken. The results suggest that people engage in excuse validation in order to avoid indirectly blaming others for blameless transgressions. Excuse validation has implications for recent debates in normative ethics, epistemology and the philosophy of language. These debates have featured thought experiments perfectly designed to trigger excuse validation, inhibiting progress in these areas

It is increasingly recognized that knowledge is the norm of assertion. As this view has gained popularity, it has also garnered criticism. One widely discussed criticism involves thought experiments about “selfless assertion.” Selfless assertions are said to be intuitively compelling examples where agents should assert propositions that they don’t even believe and, hence, don’t know. This result is then taken to show that knowledge is not the norm of assertion. This paper reports four experiments demonstrating that “selfless assertors” are viewed as both believing and knowing the propositions they assert: this is the natural and intuitive way of interpreting the case. Thought experiments about selfless assertions do not threaten the knowledge account and they do not motivate weaker alternative accounts. The discussion also highlights a general lesson for philosophers: thought experiments intended to probe for mental state attributions should not conflict with basic principles that guide social cognition

Contemporary philosophers nearly unanimously endorse knowledge reliabilism, the view that knowledge must be reliably produced. Leading reliabilists have suggested that reliabilism draws support from patterns in ordinary judgments and intuitions about knowledge, luck, reliability, and counterfactuals. That is, they have suggested a proto-reliabilist hypothesis about “commonsense” or “folk” epistemology. This paper reports nine experimental studies (N = 1262) that test the proto-reliabilist hypothesis by testing four of its principal implications. The main findings are that (a) commonsense fully embraces the possibility of unreliable knowledge, (b) knowledge judgments are surprisingly insensitive to information about reliability, (c) “anti-luck” intuitions about knowledge have nothing to do with reliability specifically, and (d) reliabilists have mischaracterized the intuitive counterfactual properties of knowledge and their relation to reliability. When combined with the weakness of existing arguments for reliabilism and the recent emergence of well supported alternative views that predict the widespread existence of unreliable knowledge, the present findings are the final exhibit in a conclusive case for abandoning reliabilism in epistemology. I introduce an alternative theory of knowledge, abilism, which out-performs reliabilism and well explains all the available evidence.

Infinitism, along with foundationalism and coherentism, is a logically possible solution to the epistemic regress problem. But unlike the other two views, infinitism has only been developed and defended as a plausible solution since the late 1990’s. Infinitists grant that although there is an ending point of any actual chain of cited reasons for a belief, no belief (including the last one cited) is fully justified until a reason for it is provided. In addition to differing with foundationalism about the existence of so-called basic beliefs, infinitism depicts reasoning as a process through which full doxastic justification is generated, rather than as a device for merely transferring doxastic justification from one belief to another. Thus, like coherentism, infinitism attempts to account for the origin of epistemic doxastic justification without invoking self-justified beliefs whose justification is transmitted through reasoning. But infinitism parts company with coherentism by maintaining (1) that circular reasoning is unable to provide a doxastic justification for any belief and (2) that there is a linear epistemic structure of our beliefs that reflects the fact that some beliefs are epistemically prior to others.

Traditionally it has been thought that the moral valence of a proposition is, strictly speaking, irrelevant to whether someone knows that the proposition is true, and thus irrelevant to the truth-value of a knowledge ascription. On this view, it’s no easier to know, for example, that a bad thing will happen than that a good thing will happen (other things being equal). But a series of very surprising recent experiments suggest that this is actually not how we view knowledge. On the contrary, people are much more willing to ascribe knowledge of a bad outcome. This is known as the epistemic side-effect effect (ESEE), and is a specific instance of a widely documented phenomenon, the side-effect effect (a.k.a. “the Knobe effect”), which is the most famous finding in experimental philosophy. In this paper, I report a new series of five experiments on ESEE, and in the process accomplish three things. First, I confirm earlier findings on the effect. Second, I show that the effect is virtually unlimited. Third, I introduce a new technique for detecting the effect, which potentially enhances its theoretical significance. In particular, my findings make it more likely that the effect genuinely reflects the way we think about and ascribe knowledge, rather than being the result of a performance error.