Adam Feltz

Critical thinking classes are ubiquitous in U.S. college curricula. One of their aims is to teach good reasoning skills. To date, there is little systematic evidence that they do this. We report the results of a field experiment (N =397) that compared undergraduate critical thinking classes taught in a philosophy department to other undergraduate philosophy classes. The results suggest that an appropriately designed critical thinking class can dramatically reduce 4 common biases in judgment and decision making: honoring sunk costs, inferring causation from correlation, ignoring regression to the mean, and overlooking opportunity costs. The size of the debiasing effects were substantial (Cohen’s d > 0.80) and persisted at least 16 months after the class ended.

Empirically minded researchers (e.g., experimental philosophers) have begun exploring the “folk” notion of intentional action, often with surprising results. In this paper, we extend these lines of research and present new evidence from a radically new paradigm in experimental philosophy. Our results suggest that in some circumstances people make strikingly different judgments about intentions and intentionality as a function of whether the person brings about or observes an event. Implications for traditional action theory and the experimental study of folk intuitions are discussed.

We present evidence indicating new individual differences with people's intuitions about the relation of determinism to freedom and moral responsibility. We analysed participants' written explanations of why a person acted. Participants offered one of either 'decision' or 'causal' based explanations of behaviours in some paradigmatic cases. Those who gave causal explanations tended to have more incompatibilist intuitions than those who gave decision explanations. Importantly, the affective content of a scenario influenced the type of explanation given. Scenarios containing highly affective actions (e.g. murder) tended to generate more decision explanations than scenarios with low affective content (e.g. cheating on taxes). These results give important clues about the proximal processes generating some intuitions about free will and moral responsibility.

Research suggests that ethical principles expressed in professional ethics codes can be diverse and not systematic. We present data suggesting there may be substantial agreement about ethical principles expressed in professional ethics codes. In a textual analysis using topic models, co-occurrence matrices, and word clouds of 200 professional ethics codes taken from 20 professional sectors identified by the U.S. Bureau of Labor Statistics, we found evidence, at least implicitly, for five general, ethical principles stated in the American Psychological Association’s Ethical Principles for Psychologists and Code of Conduct (APA, 2017): Beneficence and Nonmaleficence, Fidelity and Responsibility Integrity, Justice, and Respect for People’s Rights and Dignity. These general, ethical principles may be expressed in different ways in individual professional ethics codes, thereby potentially explaining the apparent diversity of principles in professional ethics codes.

We start with a simple question: How should you live your life? There is fundamental philosophical disagreement about the right answer to that question. While philosophical disagreement is nothing new, this chapter presents a novel perspective on a potential explanation for some of that disagreement—i.e., heritable differences in personality. We introduce some of the materials and methods that we have used to scientifically establish the relation of personality with some philosophical judgments in free will, intentional action, and moral objectivism. Readers are invited to consider some of the specific cases and questions we have used to provide evidence for the theoretical core of the book—i.e., the Philosophical Personality Argument. The conclusion of this argument states that one’s endorsement of some philosophical claims is partially a function of one’s personality. Finally, we provide potential guides for reading the book based on the interests of the reader (e.g., considering strengths and limits of empirical evidence; theoretical implications for philosophy and psychology; ethical policy analysis for choice architecture and human factors research).

Judgments about freedom and moral responsibility have been argued to be essential to how we view ourselves and others. Being free and morally responsible (or at least a belief to that effect) has been argued to underwrite elements of human existence ranging from one’s sense of self-worth to having genuine, loving relationships. One extensively explored question in the philosophical literature about freedom and moral responsibility is: can you be free and morally responsible if all your actions are determined? There is substantial philosophical disagreement about the right answer to that question. Those who answer “yes” are called compatibilists and those who answer “no” are called incompatibilists. This chapter documents extensive evidence using representative and diverse materials and methods indicating that the global personality trait extraversion predicts those who tend to be compatibilists. These relations have also been observed to exist in diverse cultures and languages (e.g., those who speak English, Spanish, or German in North America and Europe). The evidence presented in this chapter represents the paradigmatic example in our book of personality predicting philosophically relevant judgments.

Judging that somebody does something intentionally is a key element in interpersonal relationships. If somebody does something good intentionally, they are more apt targets for praise and rewards. If somebody does something bad intentionally, they are more apt targets for blame and punishment. But what is involved in acting intentionally? Again, there is substantial philosophical disagreement about the right answer to that question. Important cases that have been used to test theories about intentional action involve side effects of actions. Research shows there is a tendency for good side effects to be judged as not intentionally brought about, yet bad side effects are judged to be intentionally brought about. This chapter documents that this judgment asymmetry is predicted by the global personality trait extraversion. Those who are extraverted tend to judge that bad side effects are intentionally brought about whereas introverts do not agree that bad side effects are intentional, even after controlling for a host of other factors including concepts of intuitional action, other personality traits, and cognitive skills. We also present evidence that we can predictably manipulate intentionality judgments of side effects based on what we know about judgment tendencies of extraverts.

The first chapter asked: “How should you live your life?” The final chapter of the book asks a slightly different, but related, question: “Who should decide how you live your life?” These two questions take on additional importance due to increases in the ability to track behavior and manipulate decisions via advances in science and technology. We attempt to give some evidence-based, theoretically grounded insight into how to manage the development of decision technologies, including choice architectures, in the face of value diversity. To illustrate, we center on some potential trade-offs between two values that have been prominent and well-represented cross-culturally and in many professional and personal contexts: autonomy and beneficence. The resulting Ethical Interaction Theory provides a framework designed to offer techniques to quantify and compare ethical risks and benefits associated with the development of interactive systems (e.g., ethical policy analysis). We contextualize this approach by comparing two different kinds of choice architecture strategies—nudging and strategies that promote representative understanding. Based on these analyses, we offer a heuristic checklist to use when comparing different prescriptive interventions designed to help people make better decisions.

In this chapter we directly address one of the prominent objections to generalizing studies done on non-professional philosophers to experts in philosophy. The Expertise Defense holds that because of the special training, knowledge, or skills of professional philosophers, the potentially problematic biases found in non-professional philosophers will not likely be found in expert philosophers. To assess this argument, we provide a substantial discussion on how expertise is acquired. We focus on the facts that experts are always made and not born, general intelligence cannot explain all there is to expertise, and experts have different knowledge and skills than non-experts. We then use these general points to argue that philosophers are not likely to have the relevant kinds of learning environments, skills, or knowledge that prevents them from being biased in potentially problematic ways. We report results directly testing whether extraversion predicts compatibilist judgments about freedom and moral responsibility in philosophical experts, finding that indeed expert philosophers tend to be biased by their heritable personality traits. We conclude that without further evidence, we do not have reason to think that philosophical expertise will eliminate potentially problematic biases in philosophically relevant judgments.

Ethics is a philosophical area of study ranging from exploring the nature of morality, identifying what makes right actions right and wrong actions wrong, characterizing virtues, and weighing in on applied issues such as capital punishment and abortion. In this chapter, we present evidence that personality can predict some judgments across a range of ethical pursuits. Openness to experience predicts those who are likely to make moral objectivist judgments (i.e., that some actions are right or wrong regardless of what one thinks). Emotional stability predicts those who are likely to attribute virtues to others. Conscientiousness predicts preferences for overall less safe products (e.g., vaccines or cars) when there was no chance that the product itself would cause injuries or death. We go on to discuss the implications of empirical results for normative projects like ethics and conclude that empirical results are relevant for normative projects. This chapter represents the last extended discussion of the empirical data linking personality traits to philosophically relevant judgments.

The philosophical heart of this book is embodied in the Philosophical Personality Argument, which is:Philosophically relevant intuitions are used as some evidence for the truth of some philosophical claims.Some differences in philosophically relevant intuitions used as evidence for the truth of some philosophical claims are systematically related to some differences in personality.If philosophically relevant intuitions are used as some evidence for the truth of some philosophical claims and those intuitions are systematically related to some differences in personality, then one’s endorsement of some philosophical claims is at least partially a function of one’s personality.Therefore, one’s endorsement of some philosophical claims is at least partially a function of one’s personality.In this chapter, we provide reasons to think (1) is true. We review evidence from Chaps. 2–4 providing reasons to think (2) is true. We discuss how premise (3) seems to capture standard ways that intuitions could be used as evidence. We then argue that the conclusion (4) poses substantial challenges to some philosophical projects (e.g., Neo-Platonic projects) but not necessarily others (e.g., conceptual analysis). We then defend premises 1–3 from several objections.

This book details the discovery and exploration of one of the major scientific revelations that has emerged from the field of experimental philosophy—i.e., that heritable personality traits often predict philosophical diversity and disagreement, and may help explain fundamental philosophical biases. Adam Feltz and Edward T. Cokely provide historical and personal perspectives on this differential approach within experimental philosophy and discuss how theoretical considerations and insights have started to have practical impact on practice in risk communication, law, medicine, public policy, and engineering (e.g., science for informed decision making; the ethics of choice architecture and nudges). The main goal in this book is to provide a theoretical framework for understanding variation in fundamental philosophical intuitions and how that variation informs ethical interaction theory. This is an open access book.

This chapter provides empirical evidence about everyday attitudes concerning euthanasia. These attitudes have important implications for some ethical arguments about euthanasia. Two experiments suggested that some different descriptions of euthanasia have modest effects on people’s moral permissibility judgments regarding euthanasia. Experiment 1 (N = 422) used two different types of materials (scenarios and scales) and found that describing euthanasia differently (‘euthanasia’, ‘aid in dying’, and ‘physician assisted suicide’) had modest effects (≈ 3% of the total variance) on permissibility judgments. These effects were largely replicated in Experiment 2 (N = 409). However, in Experiment 2, judgments about euthanasia’s moral permissibility were best predicted by the voluntariness of the treatment. Voluntariness was a stronger predictor than some demographic factors and some domain general elements of moral judgments. These results help inform some debates about the moral permissibility of euthanasia (e.g., the slippery slope argument) suggesting that some of the key premises of those arguments are unwarranted.

According to intellectualism, what a person knows is solely a function of the evidential features of the person's situation. Anti-intellectualism is the view that what a person knows is more than simply a function of the evidential features of the person's situation. Jason Stanley (2005) argues that, in addition to “traditional factors,” our ordinary practice of knowledge ascription is sensitive to the practical facts of a subject's situation. In this paper, we investigate this question empirically. Our results indicate that Stanley's assumptions about knowledge ascriptions do not reflect our ordinary practices in some paradigmatic cases. If our data generalize, then arguments for anti-intellectualism that rely on ordinary knowledge ascriptions fail: the case for anti-intellectualism cannot depend on our ordinary practices of knowledge ascription.

Heritable personality traits often predict fundamental philosophical disagreement. This conclusion is based on studies of more than 15,000 people sampled from diverse cultures and educational backgrounds, including verifiable experts. In this chapter, we review some of this research showing links between personality and philosophical bias in free will, intentional action, and ethics. Our discussion focuses on serious challenges that these philosophical biases pose (e.g., limits on the use of philosophical intuitions as evidence). We close with discussion of the Philosophical Personality Argument and brief consideration of emerging projects in applied experimental philosophy.

In a series of recent papers, Walter Sinnott-Armstrong has used findings in social psychology to put pressure on the claim that our moral beliefs can be non-inferentially justified. More specifically, he has suggested that insofar as our moral intuitions are subject to what psychologists call framing effects, this poses a real problem for moral intuitionism. In this paper, we are going to try to add more fuel to the empirical fire that Sinnott-Armstrong has placed under the feet of the intuitionist. Along the way, we first provide an overview of what Sinnott-Armstrong calls the Master Argument against intuitionism. Then we examine some of the literature on framing effects—especially as it pertains to moral philosophy. Finally, we present the results of a new study which create yet another hurdle intuitionists must clear if they want to motivate their view. It appears that in addition to being influenced by framing effects, our moral intuitions are also influenced by an actor–observer bias as well—a bias whereby we hold other people to different moral standards than we would hold ourselves even if we were in the same situation. If we’re right, the burden is on the moral intuitionist to explain why we should have faith in our moral intuitions despite the gathering evidence concerning their seeming unreliability. And by our lights, this is something that simply cannot be done from the armchair.

Perhaps personality traits substantially influence one’s philosophically relevant intuitions. This suggestion is not only possible, it is consistent with a growing body of empirical research: Personality traits have been shown to be systematically related to diverse intuitions concerning some fundamental philosophical debates. We argue that this fact, in conjunction with the plausible principle that almost all adequate philosophical views should take into account all available and relevant evidence, calls into question some prominent approaches to traditional philosophical projects. To this end, we present the Philosophical Personality Argument (PPA). We explain how it supports the growing body of evidence challenging some of the uses of intuitions in philosophy, and we defend it from some criticisms of empirically based worries about intuitions in philosophy. We conclude that the current evidence indicates that the PPA is sound, and thus many traditional philosophical projects that use intuitions must become substantially more empirically oriented.

Experimental research suggests that people draw a moral distinction between bad outcomes brought about as a means versus a side effect (or byproduct). Such findings have informed multiple psychological and philosophical debates about moral cognition, including its computational structure, its sensitivity to the famous Doctrine of Double Effect, its reliability, and its status as a universal and innate mental module akin to universal grammar. But some studies have failed to replicate the means/byproduct effect especially in the absence of other factors, such as personal contact. So we aimed to determine how robust the means/byproduct effect is by conducting a meta-analysis of both published and unpublished studies (k = 101; 24,058 participants). We found that while there is an overall small difference between moral judgments of means and byproducts (standardized mean difference = 0.87, 95% CI 0.67 – 1.06; standardized mean change = 0.57, 95% CI 0.44 – 0.69; log odds ratio = 1.59, 95% CI 1.15 – 2.02), the mean effect size is primarily moderated by whether the outcome is brought about by personal contact, which typically involves the use of personal force.

In the free will literature, some compatibilists and some incompatibilists claim that their views best capture ordinary intuitions concerning free will and moral responsibility. One goal of researchers working in the field of experimental philosophy has been to probe ordinary intuitions in a controlled and systematic way to help resolve these kinds of intuitional stalemates. We contribute to this debate by presenting new data about folk intuitions concerning freedom and responsibility that correct for some of the shortcomings of previous studies. These studies also illustrate some problems that pertain to all of the studies that have been run thus far.

Currently, there are many advocacy interventions aimed at reducing animal consumption. We report results from a lab (N = 267) and a field experiment (N = 208) exploring whether, and to what extent, some of those educational interventions are effective at shifting attitudes and behavior related to animal consumption. In the lab experiment, participants were randomly assigned to read a philosophical ethics paper, watch an animal advocacy video, read an advocacy pamphlet, or watch a control video. In the field experiment, we measured the impact of college classes with animal ethics content versus college classes without animal ethics content. Using a pretest, post-test matched control group design, humane educational interventions generally made people more knowledgeable about animals used as food and reduced justifications and speciesist attitudes supporting animal consumption. None of the interventions in either experiment had a direct, measurable impact on self-reported animal consumption. These results suggest that while some educational interventions can change beliefs and attitudes about animal consumption, those same interventions have small impacts on animal consumption.

Knowledge of human uses of animals is an important, but understudied, aspect of how humans treat animals. We developed a measure of one kind of knowledge of human uses of animals – knowledge of factory farming. Studies 1 (N = 270) and 2 (N = 270) tested an initial battery of objective, true or false statements about factory farming using Item Response Theory. Studies 3 (N = 241) and 4 (N = 278) provided evidence that responses to a 10-item Knowledge of Factory Farming Scale predicted a reduction in consumption of animal products (rs = −.17- −.27) and approval of political actions aimed at factory farming (rs = .2 – .24). Path models from Studies 3 and 4 suggested that different kinds of knowledge uniquely predicted different outcomes. The Knowledge of Factory Farming scale was a unique predictor of approval of political actions concerning factory farmed animals but not animal consumption. Knowledge of Animals Used as Food predicted animal consumption but not political actions concerning farmed animals. These results highlight that different kinds of knowledge can be relevant for different animal related outcomes.

A number of philosophers have recently become increasingly interested in the potential usefulness of fictitious and illusory beliefs.As a result, a wide variety of fictionalisms and illusionisms have sprung up in areas ranging anywhere from mathematics and modality to morality.1 In this paper, we focus on the view that Saul Smilansky has dubbed “free will illusionism”—for example, the purportedly descriptive claim that the majority of people have illusory beliefs concerning the existence of libertarian free will, coupled with the normative claim that because dispelling these illusions would produce negative personal and societal consequences, those of us who are unfortunate enough to know the dangerous and gloomy truth about the nonexistence of libertarian free will should simply keep quiet in the name of the common good.

Are people are product literate enough to make informed decisions about plant-based and animal-based milk products? In 8 studies, we provide evidence that consumers do not make mistakes indicative of pervasive lack of milk product literacy. People were accurate at identifying plant-based and animal-based milk and cheese products as being plant or animal-based (74% - 84% of the time). In a more difficult task, participants were generally accurate at identifying nutritional differences between plant-based and animal-based milk and cheese products (50%–62% accuracy). We also developed the Milk Literacy Scale, which is a 12-item, validated, knowledge-based instrument that measures knowledge of differences among plant-based and animal-based milk products. The Milk Literacy Scale predicted accuracy in both identification tasks. All results were replicated in a large sample (N = 1054). These results suggest that people are generally product literate about milk products to make informed choices. The studies offer some insights into what kinds of interventions would help make people even more product literate.

Some theorists argue that appropriate responses to terrorism are in part shaped by popular sentiment. In two experiments, using representative design and ecological stimuli (e.g. actual news reports), we present evidence for some of the ways popular sentiment about terrorism tracks theory and can be constructed. In Experiment 1, we document that using the word ‘terrorist’ to describe a group of people decreases willingness to understand the group's grievances, decreases willingness to negotiate with the group, increases perceived permissibility of violence against the group, and decreases the perceived rationality of the group. In Experiment 2, we demonstrate that judgment about the permissibility of the use of force against terrorist groups can be biased by simple memory-priming manipulations. Results are interpreted in terms of (1) implications for philosophical theories about terrorism and (2) the role that experimental investigation can play in applied ethics.

Experimental philosophy is a new approach to philosophy that incorporates the experimental methodologies of psychology, behavioral economics, and sociology. Experimental philosophers generally maintain that, in addition to traditional philosophical practices, these ways of gathering evidence can be instrumental in shedding light on philosophically important issues. Rather than relying on their own intuitions about specific cases, experimental philosophers perform systematic experiments to determine what intuitions people have about those cases. These intuitions are then used as evidence. In this context, four main approaches to experimental philosophy are introduced, a sample of experimental philosophy's results is offered, and some of the philosophical importance of those results is explained.

Our theoretical understanding of individual differences can be used as a tool to test and refine theory. Individual differences are useful because judgments, including philosophically relevant intuitions, are the predictable products of the fit between adaptive psychological mechanisms (e.g., heuristics, traits, skills, capacities) and task constraints. As an illustration of this method and its potential implications, our target article used a canonical, representative, and affectively charged judgment task to reveal a relationship between the heritable personality trait extraversion and some compatabilist judgments. In the current Reply, we further clarify major theoretical implications of these data and outline potential opportunities and obstacles for this methodology. Discussion focuses on (1) the need for theoretically grounded a priori predictions; (2) the use of precise process level data and theory; (3) the possibility of convergent validity as personality is known to predict life experiences and outcomes; and (4) the fundamentally adaptive nature of cognition.

Many philosophers have worried about what philosophy is. Often they have looked for answers by considering what it is that philosophers do. Given the diversity of topics and methods found in philosophy, however, we propose a different approach. In this article we consider the philosophical temperament, asking an alternative question: what are philosophers like? Our answer is that one important aspect of the philosophical temperament is that philosophers are especially reflective: they are less likely than their peers to embrace what seems obvious without questioning it. This claim is supported by a study of more than 4,000 philosophers and non-philosophers, the results of which indicate that even when we control for overall education level, philosophers tend to be significantly more reflective than their peers. We then illustrate this tendency by considering what we know about the philosophizing of a few prominent philosophers. Recognizing this aspect of the philosophical temperament, it is natural to wonder how philosophers came to be this way: does philosophical training teach reflectivity or do more reflective people tend to gravitate to philosophy? We consider the limitations of our data with respect to this question and suggest that a longitudinal study be conducted

In a series of five experiments, we demonstrate that moral judgments and folk intuitions are often predictably fragmented. Drawing on the domains of ethics and action theory, we illustrate ways in which judgment tends to be associated with stable individual differences such as personality traits and reflective cognitive styles. We argue that these individual differences pose several unique challenges as well as provide opportunities for further theoretical development in the emerging field of experimental philosophy. Implications are briefly discussed.