Joshua Knobe

The Twin Earth thought experiment invites us to consider a liquid that has all of the superficial properties associated with water (clear, potable, etc.) but has entirely different deeper causal properties (composed of “XYZ” rather than of H2O). Although this thought experiment was originally introduced to illuminate questions in the theory of reference, it has also played a crucial role in empirically informed debates within the philosophy of psychology about people’s ordinary natural kind concepts. Those debates have sought to accommodate an apparent fact about ordinary people’s judgments: Intuitively, the Twin Earth liquid is not water. We present results from four experiments showing that people do not, in fact, have this intuition. Instead, people tend to have the intuition that there is a sense in which the liquid is not water but also a sense in which it is water. We explore the implications of this finding for debates about theories of natural kind concepts, arguing that it supports views positing two distinct criteria for membership in natural kind categories – one based on deeper causal properties, the other based on superficial, observable properties.

When agents violate norms, they are typically judged to be more of a cause of resulting outcomes. In this paper, we suggest that norm violations also affect the causality attributed to other agents, a phenomenon we refer to as "causal superseding." We propose and test a counterfactual reasoning model of this phenomenon in four experiments. Experiments 1 and 2 provide an initial demonstration of the causal superseding effect and distinguish it from previously studied effects. Experiment 3 shows that this causal superseding effect is dependent on a particular event structure, following a prediction of our counterfactual model. Experiment 4 demonstrates that causal superseding can occur with violations of non-moral norms. We propose a model of the superseding effect based on the idea of counterfactual sufficiency.

People sometimes explain behavior by appealing to an essentialist concept of the self, often referred to as the true self. Existing studies suggest that people tend to believe that the true self is morally virtuous; that is deep inside, every person is motivated to behave in morally good ways. Is this belief particular to individuals with optimistic beliefs or people from Western cultures, or does it reflect a widely held cognitive bias in how people understand the self? To address this question, we tested the good true self theory against two potential boundary conditions that are known to elicit different beliefs about the self as a whole. Study 1 tested whether individual differences in misanthropy—the tendency to view humans negatively—predict beliefs about the good true self in an American sample. The results indicate a consistent belief in a good true self, even among individuals who have an explicitly pessimistic view of others. Study 2 compared true self-attributions across cultural groups, by comparing samples from an independent country and a diverse set of interdependent countries. Results indicated that the direction and magnitude of the effect are comparable across all groups we tested. The belief in a good true self appears robust across groups varying in cultural orientation or misanthropy, suggesting a consistent psychological tendency to view the true self as morally good.

We present experimental evidence that people's modes of social interaction influence their construal of truth. Participants who engaged in cooperative interactions were less inclined to agree that there was an objective truth about that topic than were those who engaged in a competitive interaction. Follow-up experiments ruled out alternative explanations and indicated that the changes in objectivity are explained by argumentative mindsets: When people are in cooperative arguments, they see the truth as more subjective. These findings can help inform research on moral objectivism and, more broadly, on the distinctive cognitive consequences of different types of social interaction.

People’s beliefs about normality play an important role in many aspects of cognition and life (e.g., causal cognition, linguistic semantics, cooperative behavior). But how do people determine what sorts of things are normal in the first place? Past research has studied both people’s representations of statistical norms (e.g., the average) and their representations of prescriptive norms (e.g., the ideal). Four studies suggest that people’s notion of normality incorporates both of these types of norms. In particular, people’s representations of what is normal were found to be influenced both by what they believed to be descriptively average and by what they believed to be prescriptively ideal. This is shown across three domains: people’s use of the word ‘‘normal” (Study 1), their use of gradable adjectives (Study 2), and their judgments of concept prototypicality (Study 3). A final study investigated the learning of normality for a novel category, showing that people actively combine statistical and prescriptive information they have learned into an undifferentiated notion of what is normal (Study 4). Taken together, these findings may help to explain how moral norms impact the acquisition of normality and, conversely, how normality impacts the acquisition of moral norms.

Generic statements express generalizations about categories. Current theories suggest that people should be especially inclined to accept generics that involve threatening information. However, previous tests of this claim have focused on generics about non-human categories, which raises the question of whether this effect applies as readily to human categories. In Experiment 1, adults were more likely to accept generics involving a threatening property for artifacts, but this negativity bias did not also apply to human categories. Experiment 2 examined an alternative hypothesis for this result, and Experiments 3 and 4 served as conceptual replications of the first experiment. Experiment 5 found that even preschoolers apply generics differently for humans and artifacts. Finally, Experiment 6 showed that these effects reflect differences between human and non-human categories more generally, as adults showed a negativity bias for categories of non-human animals, but not for categories of humans. These findings suggest the presence of important, early-emerging domain differences in people's judgments about generics.

Over the past several decades, psychological essentialism has been an important topic of study, incorporating research from multiple areas of psychology, philosophy and linguistics. At its most basic level, essentialism is the tendency to represent certain concepts in terms of a deeper, unobservable property that is responsible for category membership. Originally, this concept was used to understand people’s reasoning about natural kind concepts, such as TIGER and WATER, but more recently, researchers have identified the emergence of essentialist-like intuitions in a number of other contexts, including people’s representation of concepts like SCIENTIST or CHRISTIAN. This paper develops an account that aims to capture how essentialism may operate across these varied cases. In short, we argue that while there is diversity in the forms essentialism can take, these varied cases reflect the same underlying cognitive structure.

Past research has identified a number of asymmetries based on moral judgments. Beliefs about what a person values, whether a person is happy, whether a person has shown weakness of will, and whether a person deserves praise or blame seem to depend critically on whether participants themselves find the agent's behavior to be morally good or bad. To date, however, the origins of these asymmetries remain unknown. The present studies examine whether beliefs about an agent's “true self” explain these observed asymmetries based on moral judgment. Using the identical materials from previous studies in this area, a series of five experiments indicate that people show a general tendency to conclude that deep inside every individual there is a “true self” calling him or her to behave in ways that are morally virtuous. In turn, this belief causes people to hold different intuitions about what the agent values, whether the agent is happy, whether he or she has shown weakness of will, and whether he or she deserves praise or blame. These results not only help to answer important questions about how people attribute various mental states to others; they also contribute to important theoretical debates regarding how moral values may shape our beliefs about phenomena that, on the surface, appear to be decidedly non-moral in nature.

Claims about people's intuitions have long played an important role in philosophical debates. The new field of experimental philosophy seeks to subject such claims to rigorous tests using the traditional methods of cognitive science – systematic experimentation and statistical analysis. Work in experimental philosophy thus far has investigated people's intuitions in philosophy of language, philosophy of mind, epistemology, and ethics. Although it is now generally agreed that experimental philosophers have made surprising discoveries about people's intuitions in each of these areas, considerable disagreement remains about the philosophical significance of the key findings. Some have argued that work in experimental philosophy should be assessed by asking whether it can contribute to the kind of inquiry that is normally pursued within analytic philosophy, while others suggest that work in experimental philosophy is best understood as a contribution to a more traditional sort of philosophical inquiry that long predates the birth of analytic philosophy

In earlier work, I relied on a commonly-held view about the relationship between the concept of acting intentionally and the concept of performing a behavior in order to achieve a goal. Eric Wiland responds that it was actually a mistake to rely on this view and that the relationship between these concepts is far more complex than was previously thought. I now think that Wiland may be right to reject my earlier approach, and I therefore provide additional empirical support for his basic claim. 2012 APA, all rights reserved)

Recent developments in cosmology indicate that every history having a non-zero probability is realized in infinitely many distinct regions of spacetime. Thus, it appears that the universe contains infinitely many civilizations exactly like our own, as well as infinitely many civilizations that differ from our own in any way permitted by physical laws. We explore the implications of this conclusion for ethical theory and for the doomsday argument. In the infinite universe, we find that the doomsday argument applies only to effects which change the average lifetime of all civilizations, and not those which affect our civilization alone.

Past work has demonstrated that people’s moral judgments can influence their judgments in a number of domains that might seem to involve straightforward matters of fact, including judgments about freedom, causation, the doing/allowing distinction, and intentional action. The present studies explore whether the effect of morality in these four domains can be explained by changes in the relevance of alternative possibilities. More precisely, we propose that moral judgment influences the degree to which people regard certain alternative possibilities as relevant, which in turn impacts intuitions about freedom, causation, doing/allowing, and intentional action. Employing the stimuli used in previous research, Studies 1a, 2a, 3a, and 4a show that the relevance of alternatives is influenced by moral judgments and mediates the impact of morality on non-moral judgments. Studies 1b, 2b, 3b, and 4b then provide direct empirical evidence for the link between the relevance of alternatives and judgments in these four domains by manipulating (rather than measuring) the relevance of alternative possibilities. Lastly, Study 5 demonstrates that the critical mechanism is not whether alternative possibilities are considered, but whether they are regarded as relevant. These studies support a unified framework for understanding the impact of morality across these very different kinds of judgments.

A growing body of research has examined how people judge the persistence of identity over time—that is, how they decide that a particular individual is the same entity from one time to the next. While a great deal of progress has been made in understanding the types of features that people typically consider when making such judgments, to date, existing work has not explored how these judgments may be shaped by normative considerations. The present studies demonstrate that normative beliefs do appear to play an important role in people's beliefs about persistence. Specifically, people are more likely to judge that the identity of a given entity remains the same when its features improve than when its features deteriorate. Study 1 provides a basic demonstration of this effect. Study 2 shows that this effect is moderated by individual differences in normative beliefs. Study 3 examines the underlying mechanism, which is the belief that, in general, various entities are essentially good. Study 4 directly manipulates beliefs about essence to show that the positivity bias regarding essences is causally responsible for the effect

Since the earliest days of analytic philosophy, it has been a common practice to appeal to intuitions about particular cases. Typically, the philosopher presents a hypothetical situation and then makes a claim of the form: ‘In this case, we would surely say....’ This claim about people’s intuitions then forms a part of an argument for some more general theory about the nature of our concepts or our use of language. One puzzling aspect of this practice is that it so rarely makes use of standard empirical methods. Although philosophers quite frequently make claims about ‘what people would ordinarily say,’ they rarely back up those claims by actually asking people and looking for patterns in their responses. In recent years, however, a number of philosophers have tried to put claims about intuitions to the test, using experimental methods to figure out what people really think about particular hypothetical cases. At times, the results have been extremely surprising. Here I discuss applications of this new methodology to three areas of philosophy — the philosophy of language, the theory of action, and the free will debate

Contemporary moral psychology has been dominated by two broad traditions, one usually associated with Aristotle, the other with Kant. The broadly Aristotelian approach emphasizes the role of childhood upbringing in the development of good moral character, and the role of such character in ethical behavior. The broadly Kantian approach emphasizes the role of freely chosen conscious moral principles in ethical behavior. We review a growing body of experimental evidence that suggests that both of these approaches are predicated on an implausible view of human psychology. This evidence suggests that both childhood upbringing and conscious moral principles have extraordinarily little impact on people's moral behavior. This paper argues that moral psychology needs to take seriously a third approach, derived from Nietzsche. This approach emphasizes the role of heritable psychological and physiological traits in explaining behavior. In particular, it claims that differences in the degree to which different individuals behave morally can often be traced back to heritable differences between those individuals. We show that this third approach enjoys considerable empirical support - indeed that it is far better supported by the empirical data than are either the Aristotelian or Kantian traditions in moral psychology.

The psychological study of ethical reasoning tends to concentrate on a few specific issues, with the bulk of the research going to the study of people's attitudes toward moral rules or the welfare of others. But people's ethical reasoning is also shaped by a wide range of other concerns. Here I focus on the importance that people attach to the ideal of being yourself. It is shown that certain experimental results - results that seemed anomalous and inexplicable to researchers who focused on moral rules and concern for the welfare of others - can be explained quite elegantly as the product of people's attachment to the ideal of 'being yourself'. The success of this explanation then points to the need for a more general inquiry into the role that the ideal of 'being yourself ' plays in people's ethical reasoning.

Suppose that Ann says, “Keith knows that the bank will be open tomorrow.” Her audience may well agree. Her knowledge ascription may seem true. But now suppose that Ben—in a different context—also says “Keith knows that the bank will be open tomorrow.” His audience may well disagree. His knowledge ascription may seem false. Indeed, a number of philosophers have claimed that people’s intuitions about knowledge ascriptions are context sensitive, in the sense that the very same knowledge ascription can seem true in one conversational context but false in another. This purported fact about people’s intuitions serves as one of the main pieces of evidence for epistemic contextualism.