Is probabilistic evidence a source of knowledge?

We report a series of experiments examining whether people ascribe knowledge for true beliefs based on probabilistic evidence. Participants were less likely to ascribe knowledge for beliefs based on probabilistic evidence than for beliefs based on perceptual evidence or testimony providing causal information. Denial of knowledge for beliefs based on probabilistic evidence did not arise because participants viewed such beliefs as unjustified, nor because such beliefs leave open the possibility of error. These findings rule out traditional philosophical accounts for why probabilistic evidence does not produce knowledge. The experiments instead suggest that people deny knowledge because they distrust drawing conclusions about an individual based on reasoning about the population to which it belongs, a tendency previously identified by “judgment and decision making” researchers. Consistent with this, participants were more willing to ascribe knowledge for beliefs based on probabilistic evidence that is specific to a particular case. 2016 APA, all rights reserved

Four arguments for denying that lottery beliefs are justified

A ‘lottery belief’ is a belief that a particular ticket has lost a large, fair lottery, based on nothing more than the odds against it winning. The lottery paradox brings out a tension between the idea that lottery beliefs are justified and the idea that that one can always justifiably believe the deductive consequences of things that one justifiably believes – what is sometimes called the principle of closure. Many philosophers have treated the lottery paradox as an argument against the second idea – but I make a case here that it is the first idea that should be given up. As I shall show, there are a number of independent arguments for denying that lottery beliefs are justified

Skeptical Appeal: The Source‐Content Bias

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 psycholog

Knowledge central: A central role for knowledge attributions in social evaluations

Five experiments demonstrate the central role of knowledge attributions in social evaluations. In Experiments 1–3, we manipulated whether an agent believes, is certain of, or knows a true proposition and asked people to rate whether the agent should perform a variety of actions. We found that knowledge, more so than belief or certainty, leads people to judge that the agent should act. In Experiments 4–5, we investigated whether attributions of knowledge or certainty can explain an important finding on how people act based on statistical evidence, known as “the Wells effect”. We found that knowledge attributions, but not certainty attributions, mediate this effect on decision making. 2018 APA, all rights reserved

Experimental epistemology and "Gettier" cases

This chapter reviews some faults of the theoretical literature and findings from the experimental literature on “Gettier” cases. Some “Gettier” cases are so poorly constructed that they are unsuitable for serious study. Some longstanding assumptions about how people tend to judge “Gettier” cases are false. Some “Gettier” cases are judged similarly to paradigmatic ignorance, whereas others are judged similarly to paradigmatic knowledge, rendering it a theoretically useless category. Experimental procedures can affect how people judge “Gettier” cases. Some important central tendencies in judging “Gettier” cases appear to be robust against demographic variation in biological sex, age, language, and culture, although there could be some interesting differences related to culture and personality traits. Some remaining questions regarding Gettier’s cases, “Gettier” cases, and “the Gettier problem” concern the psychology and sociology of contemporary anglophone theoretical epistemology. Some remaining questions regarding the empirical study of knowledge judgments concern mechanisms underlying observed behavioral patterns

The Problem of ESEE Knowledge

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

Knowledge attributions and lottery cases: a review and new evidence

I review recent empirical findings on knowledge attributions in lottery cases and report a new experiment that advances our understanding of the topic. The main novel finding is that people deny knowledge in lottery cases because of an underlying qualitative difference in how they process probabilistic information. “Outside” information is generic and pertains to a base rate within a population. “Inside” information is specific and pertains to a particular item’s propensity. When an agent receives information that 99% of all lottery tickets lose (outside information), people judge that she does not know that her ticket will lose. By contrast, when an agent receives information that her specific ticket is 99% likely to lose (inside information), people judge that she knows that her ticket will lose. Despite this difference in knowledge judgments, people rate the likelihood of her ticket losing the exact same in both cases (i.e. 99%). The results shed light on other factors affecting knowledge judgments in lottery cases, including formulaic expression and participants’ own estimation of whether it is true that the ticket will lose. The results also undermine previous hypotheses offered for knowledge denial in lottery cases, including the hypotheses that people deny knowledge because they either deny justification or acknowledge a chance for error

The test of truth: An experimental investigation of the norm of assertion

Assertion is fundamental to our lives as social and cognitive beings. Philosophers have recently built an impressive case that the norm of assertion is factive. That is, you should make an assertion only if it is true. Thus far the case for a factive norm of assertion been based on observational data. This paper adds experimental evidence in favor of a factive norm from six studies. In these studies, an assertion’s truth value dramatically affects whether people think it should be made. Whereas nearly everyone agreed that a true assertion supported by good evidence should be made, most people judged that a false assertion supported by good evidence should not be made. The studies also suggest that people are consciously aware of criteria that guide their evaluation of assertions. Evidence is also presented that some intuitive support for a non-factive norm of assertion comes from a surprising tendency people have to misdescribe cases of blameless rule-breaking as cases where no rule is broken

Knowledge and Luck

Nearly all success is due to some mix of ability and luck. But some successes we attribute to the agent’s ability, whereas others we attribute to luck. To better understand the criteria distinguishing credit from luck, we conducted a series of four studies on knowledge attributions. Knowledge is an achievement that involves reaching the truth. But many factors affecting the truth are beyond our control and reaching the truth is often partly due to luck. Which sorts of luck are compatible with knowledge? We find that knowledge attributions are highly sensitive to lucky events that change the explanation for why a belief is true. By contrast, knowledge attributions are surprisingly insensitive to lucky events that threaten but ultimately fail to change the explanation for why a belief is true. These results shed light on our concept of knowledge, help explain apparent inconsistencies in prior work on knowledge attributions, and constitute progress toward a general understanding of the relation between success and luck