Introduction

Abstract

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).

How should you live your life? Considering a wide range of possible perspectives, decision theory offers a simple prescription: Just make decisions that get you more of what you should want. It’s a very straightforward recommendation. Nevertheless, it’s hard to overstate the transformative influence of decision theory and its components, including probability theory and statistics. It seems likely that nearly every living person has felt decision theory’s influence in many ways (e.g., it is an essential foundation of modern science and engineering). And with each passing day the influence of decision theory seems to be accelerating thanks to increases in knowledge, connectivity, and computing power. Yet despite its growing impact, decision theory cannot tell us what decision we should make unless we know what we should want, or more precisely what we should value. This limit presents serious challenges because a growing body of evidence indicates that humans have abiding philosophical biases that give rise to entrenched and fundamental disagreements. Some of these heritable biases are so resistant to change that it is unlikely we will ever come to consensus about the “truth” of many pressing moral and ethical debates—assuming one even exists. In at least some cases, philosophical biases and disagreements continue to persist even among verifiable experts who have devoted their lives to understanding and clarifying all relevant issues and facts. The heritability of our philosophical biases may also help explain why some philosophical debates have persisted generation after generation. But make no mistake, these empirical claims do not reflect mere armchair conjecture. Instead, they follow from intensive scientific inquiry that has unfolded over the last two decades, which has revealed consistent and converging evidence on the fragmentation and potential immutability of some of our most fundamental philosophical beliefs. As is detailed throughout this book, primary evidence can be found in nearly 100 scientific studies involving thousands of diverse participants from many cultures and countries around the world. This research confirms what some have argued for centuries: Even for the most informed and reasonable people, it may be impossible to ever agree about some of humanity’s most defining values and moral issues.

The scientific research documenting the robust nature of some philosophical disagreements provides a foundation for a formal axiomatized normative argument that has established new, strong bounds on justifiable philosophical practice and inference—i.e., the Philosophical Personality Argument. The core of this book revolves around the Philosophical Personality Argument, which is:

• 1. “Philosophically relevant intuitions are used as some evidence for the truth of some philosophical claims.

• 2. Some differences in philosophically relevant intuitions used as evidence for the truth of some philosophical claims are systematically related to some differences in personality.

• 3. 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.

• 4. Therefore, one’s endorsement of some philosophical claims is at least partially a function of one’s personality.” (Feltz & Cokely, 2012a)

We will spend the bulk of this book providing evidence for the truth of the premises (1–4) and defending them from various objections. We then discuss some of the potential implications of the Philosophical Personality Argument. Among its many implications, the Philosophical Personality Argument casts light on how and why those who engage in some efforts to determine the non-conceptual, non-linguistic truth of various fundamental philosophical and moral issues are likely to generate seemingly accurate, yet irreducibly biased and diverse conclusions. This formal approach also implies that we may be unlikely to ever have access to uncontroversial, unequivocal answers to many fundamental philosophical and ethical questions that are believed to underwrite so much of what we humans value most dearly. Moreover, the Philosophical Personality Argument indicates that those who engage in other influential projects—such as normative projects or conceptual analyses that use intuitions as essential, irreplaceable elements—also bear considerable risk for undetected bias and error in their scholarship. Beyond the obvious limits and implications that follow for philosophers, ethicists, scholars, and policy makers, we explore other implications for high-stakes decision making interventions and human welfare more broadly. Accordingly, in the last chapter our primary focus is an examination and exploration of key implications, culminating in a new normative theory and scientific framework for the science of informed decision making—i.e., Ethical Interaction Theory.

A Day in the Life

To illustrate how we came to such strong conclusions, it seems useful to look at some typical activities that philosophers and psychologists engage in. Accordingly, we’ll invite you to do some philosophy and to explore your own psychology by making some judgments and decisions. We’ll also put some skin in the game and make research-based predictions about your reactions to some paradigmatic philosophical scenarios based on your self-reported personality traits.

For a philosopher, a typical day at the office involves reading a lot. Much of this reading involves thought experiments on difficult problems. Many of these problems are about issues that have deep and meaningful implications for most people. For example, consider the following scenario:

Imagine a universe (Universe A) in which everything that happens is completely caused by whatever happened before it including human decision making. For example, one day Mary decided to have French Fries at lunch. Since a person’s decision in this universe is completely caused by what happened before it, given the things that happened in Universe A before her decisions, it had to happen that Mary would decide to have French Fries. She could not have decided to have something different.

Imagine in Universe A a man named Bill has become attracted to his secretary, and he decides that the only way to be with her is to kill his wife and 3 children. He knows that it is impossible to escape from his house in the event of a fire. Before he leaves on a business trip, he sets up a device in his basement that burns down the house and kills his family.

Take a few minutes to re-read the scenario and think about some of its key features. Once you’ve done that, please answer this question:

“Is Bill morally responsible for killing his family?”

Please go ahead and write down your answer to that question—we will return to this question later.

You have just engaged in one kind of typical philosophical activity. Of course, a lot of other things happen in a typical day as a philosopher, but thinking about cases illustrating philosophical ideas is certainly one of them. You’ve thought deeply about a case and have made a judgment about that case. That judgment, in turn, probably reflects some of the deep values that you have. To us, this exercise illustrates a wonderfully democratic aspect of philosophy. Almost all people can make judgments about the case you just read. So, in that sense, we can all take part in philosophical activity. Moreover, philosophers often take what people think very seriously when they construct their philosophical theories. After all, philosophers often want to think and theorize about things that are of central importance to human existence. Since you are an existing human, your thoughts about these issues matter too.

But there’s a challenge associated with this democratic spirit of philosophy. Suppose somebody disagreed with you about the answer to the statement “Bill is morally responsible for killing his wife.” How would you go about trying to convince that person that they are wrong? You would probably reference key elements of the scenario to justify your view, and you might then argue that those elements are the reasons why a person in that position would be as free as you judged them to be. But what would you do if you still could not convince the other person that they are wrong? What if the person with whom you disagree highlights other aspects of the scenario? Is that disagreement simply unresolvable? Does that imply that at least one of you is making a mistake? And how could you tell if one of you was making a mistake? Those are difficult, key questions that we’ll return to again and again in this book.

Shifting gears a little bit, what comes to mind when you think of a psychologist? You might be imagining somebody who invites people to sit on a couch to discuss distressing feelings or resolve personal problems. Alternatively, you may have thought of a person in a lab coat testing participants and assessing their behavior. For our current purposes, it’s the lab coat type psychologist that we would like you to focus on. A typical day for these kinds of research psychologists (like us) often involves trying to more precisely understand human psychology and behavior via empirical investigation and experimentation. For example, we sometimes create and test technologies designed to measure or improve cognitive abilities (e.g., learning, reasoning, decision making). Other times, we examine how risk communications about recycled water or natural hazards can influence our emotions, attitudes, and choices. And, of course, we also investigate the reasons people disagree about philosophically relevant judgments. But again, unlike most philosophers, psychologists primarily conduct empirical studies and experiments to investigate the reasons why people make the judgments they do. Psychologists usually also develop and validate instruments (e.g., tests, surveys, training systems) and create mathematical models of behavior, which allow them to make predictions about how and why people will behave the way they do in the future.

Philosophical Personality

Personality is one influential factor that psychologists have used to help explain and predict how people feel and what they think or do (Revelle & Scherer, 2009). You probably already have a sense for this. You know people who are outgoing and social. You can make reasonably accurate predictions about how these people will behave in different situations. You may even deliberately use ideas about people’s personality to help inform your predictions. Psychologists do the same, although they typically use systems that are more precise and scientifically grounded, based on taxonomies of personality traits. Some of the more well-known assessments developed by psychologists include the Big Five personality traits, the HEXACO traits, Myers-Brigs personality traits, and the Minnesota Multiphasic Personality Inventory (MMPI), to name just a few. Each of these approaches provides unique insights that can help predict patterns of feelings, thoughts, and behaviors. For example, the MMPI is often used to help clinicians identify and treat psychopathologies and related mental health challenges. Given our current aims, in this book we will mainly focus on what we take to be the most influential approach to adult personality traits, namely the Big Five personality model (sometimes referred to as the OCEAN traits).

The Big Five model of personal includes five “global” personality traits: Extraversion, openness to experience, emotional stability, agreeableness, and conscientiousness. The gist of each global trait is pretty much what you would expect from the labels. Extraverts enjoy social interaction, agreeable people tend to avoid conflicts, and so on. We will discuss some of the Big Five traits in greater depth in future chapters, but for readers who want to begin with a more comprehensive overview we recommend the review by John and Srivastava (1999). One thing that will be apparent in any high-quality review is that there is substantial empirical evidence showing that the Big Five personal traits are heritable (i.e., related to differences in people’s genes), which partly explains why they robustly predict patterns of feelings, behaviors, and thoughts. For example, people who are higher in the heritable trait of extraversion are more likely to take on and enjoy leadership roles (Judge, Bono, Ilies, & Gerhardt, 2002). Of course, this doesn’t mean that being highly extraverted will guarantee that a person will volunteer for, or enjoy, leadership roles. But all else equal, the evidence suggests that it’s a good bet they will.

The Big Five personality traits have also been found to be exhibited by diverse people from many unique cultures all around the world. They have been found to be relatively stable once a person hits adulthood. They also encompass a wide swath of more specific tendencies, called facets, which can provide more nuanced insights into people’s feelings and judgments. For example, extraversion is a global trait that typically encompasses individual differences in the facet of warmth—i.e., the tendency to be close and affectionate with others. This suggests that although people who are more extraverted also tend to be warmer than introverts, some extraverts are much warmer than other extraverts. As such, when it comes to philosophical and moral questions, sometimes the specific facet of personality (i.e., warmth) may be a stronger predictor of someone’s judgment than their more general global trait (i.e., extraversion). Given these and other findings, one of the central claims we will present in this book is that some of these heritable Big Five personality traits, and the specific facets thereof, help to explain (and predict) at least some noteworthy philosophically relevant judgments.

Know Yourself (and Others)

Personality tests have been shown to predict many things about people such as longevity, career outcomes, and success in marriage. If you are interested in your personality traits, you can find tests online to determine how you score on the dimensions of the Big Five. Or, you can take this quick personality test created and validated by Gosling, Rentfrow, and Swann (2003). This short ten-item test is a measure of each of the Big Five global personality traits. This measure has remarkably robust predictive power even when compared to much longer instruments that measure fine-grained facets of each personality type. To give it a try, simply rate yourself on each of the following pairs of adjectives, using a scale numbered from 1 through 7. Use 1 to indicate strong disagreement or on the opposite end of the scale use 7 to indicate strong agreement (e.g., an answer of 5 would indicate mild agreement with that pair of adjectives whereas 3 would indicate mild disagreement, and so on).

• 1. Extraverted, enthusiastic _______

• 2. Critical, quarrelsome ________

• 3. Dependable, self-disciplined ________

• 4. Anxious, easily upset ________

• 5. Open to new experience, complex ________

• 6. Reserved, quiet ________

• 7. Sympathetic, warm ________

• 8. Disorganized, careless ________

• 9. Calm, emotionally stable ________

• 10. Conventional, uncreative ________

Once you rate your agreement with these ten pairs of adjectives, you can use the following instructions to score your personality on each of the five personality factors. But please note, there’s one tricky part to calculating your score on this brief Big Five inventory. You will need to reverse score questions 2, 4, 6, 8, and 10. The basic idea behind reverse scoring is simple—take the mirror image of your score.¹ So, if you rated yourself a 1 for items 2, 4, 6, 8, or 10, then your reverse score for those items is a 7, if you rated yourself a 2 your score is 6, if 3 your score is 5, 4 says the same, but 5 then becomes 3, a score of 6 becomes 2, and a score of 7 is transformed into a 1.

• 1. Extraversion (sum of 1 and reverse score of 6) ______

• 2. Agreeableness (sum of reverse score of 2 and 7) ______

• 3. Conscientiousness (sum of 3 and reverse score of 8) ______

• 4. Emotional Stability (sum of reverse score of 4 and 9) ______

• 5. Openness to Experience (sum of 5 and reverse score of 10) ______

Here is where we are going to take a small risk in this book. We are going to try to predict how you will respond to a number of different philosophical scenarios that involve philosophically relevant concepts like freedom, morality, and intentional action using your scores to these global personality traits. We’re confident we won’t always be right. But odds are that on average we’ll do fairly well for most people, so let’s give it a shot. You’ve already responded to a paradigmatic scenario probing your thoughts about some aspects of freedom and moral responsibility. The next step is to consider and make some judgments about the next two scenarios as well:

Suppose the vice-president of a company went to the chairman of the board and said, “We are thinking of starting a new program. It will help us increase profits for this year’s balance sheet, but in ten years it will start to harm the environment.” The chairman answered, “I don’t care at all about harming the environment. I just want to make as much profit for this year’s balance sheet as I can. Let’s start the new program.” They started the new program. Sure enough, the environment started to be harmed. (Knobe, 2003a)

Think about that scenario for a few minutes. Then, write down your answer to the following question: Did the chairman intentionally harm the environment? Now, imagine a slightly different scenario (pay attention—there is a subtle difference: To help, we’ve put the difference in bold):

Suppose the vice-president of a company went to the chairman of the board and said, “We are thinking of starting a new program. It will help us increase profits for this year’s balance sheet, but in ten years it will start to help the environment.” The chairman answered, “I don’t care at all about helping the environment. I just want to make as much profit for this year’s balance sheet as I can. Let’s start the new program.” They started the new program. Sure enough, the environment started to be helped. (Knobe, 2003a)

Answer the following question: Did the chairman intentionally help the environment? Given our research, if you scored high on extraversion you are likely to think that the chairman intentionally harmed the environment yet you are also quite likely to say that the chairman did not intentionally help the environment. If you scored lower on extraversion, you’ll likely think neither was intentional. So, who is right? Some people think they know the answer… but we’re not so sure. In any event, we think differences in intuitions about intentionality revealed using cases like these may tell us something important about the origins and tractability of related higher-stakes disagreements (e.g., court cases about liabilities, criminal penalties, and fair compensation; expectations for praise and blame in personal and romantic relationships).

We’ll give you one last scenario as a taste for what is to come in the chapters that follow.

Imagine that John and Fred are members of different cultures, and they are in an argument. John says, “It’s okay to hit people just because you feel like it,” and Fred says, “No, it is not okay to hit people just because you feel like it.” John then says, “Look you are wrong. Everyone I know agrees that it’s okay to do that.” Fred responds, “Oh no, you are the one who is mistaken. Everyone I know agrees that it’s not okay to do that.”

Suppose somebody asks you who is right in the debate? Is Fred right that it is not okay to hit people just because you feel like it? Is John right that it is okay to hit people just because you feel like it? Or is there no fact of the matter about claims like hitting others just because you feel like it? (Nichols, 2004a)

Just like the previous scenarios, please take a few minutes to carefully consider the key elements of the scenario. Then, write down your answer to the question. In this case, based on previous research, we predict that if you are high in openness to experience you are more likely to think that there is no fact of the matter about hitting others just because you feel like it. However, if you are lower on openness to experience, you’re more likely to have other views. So, how did we do? Odds are we probably did well “overall, and on average,” as the saying goes. Regardless of our prediction, you might be wondering whether you gave the “right” answer. Again we really can’t tell you. Even though we have our own personal opinions, we just don’t know. That said, we feel confident that some esteemed philosophers and psychologists probably would argue that they indeed do know the right answer… but ironically if we could survey enough of these people who “know” the right answer we’d likely find that there is strong disagreement about what the “obvious” right answer “must be.” To us, that disagreement is a very interesting finding, particularly because we can use people’s heritable personality traits to predict what they will think. As such, much of this book is devoted to explaining why we make the predictions that we do, and what we think these findings mean for philosophy, psychology, and people’s lives more generally. We hope it is obvious that we take your responses to these kinds of scenarios seriously. We also take the relation of your responses to your personality seriously. And, if you decide you want to get more substantial feedback on your own philosophical personality profile, we invite you to visit our website at PhilosophicalCharacter.org. It has options to provide feedback about how you compare to others, and what implications your specific philosophical personality profile may have, and sometimes there are opportunities to volunteer to participate in studies in the future. Just please remember, we’re much better at research than webpage design, so assuming you don’t expect too much, you’ll probably be pleasantly surprised.

A Road Less Traveled

What you just did—answer a personality inventory and answer some philosophically relevant questions—is exactly how we started down the road to discovering the relations between philosophically relevant judgments and personality. Technically, we can’t quite remember (or agree about) how exactly we decided to embark on our research collaboration, which started almost 20 years ago at Florida State University. It seems likely that at least one of us was just a little more extraverted than normal while we were waiting for a research meeting to begin. One version of what happened next is that we struck up a discussion about statistics that resulted in a question about the role of individual differences in philosophical judgments. From there our work together began in earnest with an investigation of free will judgments. We thought that there might be some relation between some free will judgments and personality (i.e., extraversion) but we couldn’t find any direct test in the literature. When we discovered the relation, we were encouraged. We then started making and testing predictions about a host of philosophically relevant judgments. Although our work involved elements of psychology and philosophy, our research built primarily on the scholarly work that has come to be known as “experimental philosophy.” Experimental philosophy typically involves using some methods from psychology (and allied behavioral and social sciences) to help address some philosophically relevant questions. At the time we first started working on these issues, free will, intentional action, and moral judgments were among the dominant themes explored in experimental philosophy. Consequently, our research mainly focused on those main three domains.²

The relation between personality and philosophically relevant intuitions has many implications for theory and can also have some notable practical implications. The first theoretical implication we will discuss in this book is that the observed relationship with personality suggests that for some notable philosophical issues there probably is not any single uncontroversial “folk” view (e.g., people who feel differently about important issues can and probably should reasonably disagree on some of the philosophical issues). Nevertheless, many philosophers talk as if there is or should be a single folk view when making arguments about the “truth” of some philosophical topics (e.g., “most people would agree that…”). Taking that kind of “one size fits all” approach to the perspectives of diverse people around the world is naïve, it is contrary to a large body of scientific evidence, and it is obviously inconsistent with the characteristics of many modern political, social, and moral disagreements. From our perspective, these findings suggest that it may not be as important to try and find the “right” view, but rather to understand the reasons for philosophical disagreements, and to start to map the implications of people’s reasonable yet diverse views.

Second, the evidence we present in this book might at least partially explain why some philosophical debates have never been resolved. That is, some enduring debates may never go away simply because philosophers have different personalities, and as such they are likely to have heritable philosophical biases that shape how they feel about fundamental moral and ethical issues. Once again, because personality traits are heritable and related to core philosophical intuitions, debates that involve those intuitions seem unlikely to result in agreement about uncontroversial “correct” views about “the” truth of some philosophical issues. Moreover, this finding indicates that some philosophical methods are not nearly as reliable as previous thought, and thus many traditional philosophical projects that use intuitions as evidence should become substantially more empirically oriented, and should also become much less focused on finding “the” Neo-Platonic truth (if such a thing even exists). While this may seem like a somewhat pessimistic view, one that could also complicate the work of some philosophers in unwelcome ways, we remain optimistic for many reasons. First and foremost, we’re after the truth, even if it’s inconvenient. Secondly, by our lights this finding appears liberating and potentially empowering. After all, if we’re all biased and thus fundamentally disagree about some important issues, no matter how much we argue we’re just not going to agree… but as many have noted disagreement doesn’t mean we can’t find productive ways to respectfully consider other people’s perspectives. Accordingly, we end the book by arguing that given the increasing power of behavioral science to control our behaviors, there is a need to reconsider how we design and evaluate the technology and policies that increasingly influence our choices (e.g., the nudging versus boosting debate in behavioral economics, politics, and business).

Guide to Reading the Book

In Chap. 2, we begin to document the empirical evidence concerning the relation between personality and philosophically relevant intuitions. In many ways, Chap. 2 serves as the primary example of personality predicting intuitions about philosophically relevant judgments. In Chap. 2, we document the evidence that global personality traits predict intuitions about compatibilism, fatalism, and manipulation.

In Chap. 3, we detail personality’s relation to intentional action intuitions. These intuitions include judgments about side effects of actions that are illustrated by the two chairmen cases that you have already responded to above. We go on to demonstrate that this effect persists even after controlling people’s concepts of intentional action and for different kinds of materials and testing environments.

Chapter 4 provides evidence that personality predicts some ethically relevant intuitions. These intuitions range from intuitions about meta-ethical positions, first-order ethical positions, and applied ethical positions. One such example is the one you responded to above—whether there are facts of the matter about some ethical claims. But personality also predicts people who are likely to attribute virtues to others, and also predicts some applied ethical judgments about punishment, moral wrongness, and desert.

Chapter 5 provides an extended argument concerning one of the important objections to the kinds of claims we are making—the Expertise Defense. The existing literature on expertise suggests that in many domains and for many judgments, expertise makes a real, qualitative difference. Experts in those domains are simply better than non-experts in important respects. We detail some of the arguments, theories, and evidence about why experts often make better judgments than non-experts. We go on to argue that philosophy is not likely to be one of those domains, at least for many of the judgments that are of interest. We also provide an empirical test of the expertise defense and find that personality predicts intuitions about freedom and moral responsibility even among verified experts. These results suggest that for many philosophical domains and judgments, the expertise defense fails.

In Chap. 6, we present the Philosophical Personality Argument that you encountered at the beginning of this chapter. In short, the argument presents an axiomatized, deductive, normative argument based on the diversity of philosophical intuitions associated with personality. Given that personality is irrelevant to the truth of the content of intuitions, we argue that some philosophical practices that attempt to establish the mind-independent, non-linguistic, non-conceptual truth using those intuitions run the risk of not being able to succeed. We take this chapter to be the philosophical core of the book.

Chapter 7 takes the key insights from the Philosophical Personality Argument and draws practical implications. Even though philosophical values are importantly diverse, there is large consensus among people and cross-culturally that there are some core values. Autonomy and beneficence are two core values that have received relatively large consensus. Striking a balance between these two values has been challenging and the subject of much debate. One important and popular approach to negotiating this balance is Libertarian Paternalism. Libertarian Paternalism attempts to help people engage in better behaviors (thereby promoting beneficence) while at the same time protecting freedom of choice (thereby respecting autonomy). However, we argue that there are significant ethical costs associated with Libertarian Paternalism that are often neglected, especially when considered in light of systematic diversity of philosophical values. To help address these concerns, we present a new complementary theory, Ethical Interaction Theory, and argue that it is likely both necessary and useful for studying human interactions and designing choice architecture (e.g., user interfaces), that respects and promotes autonomy and diversity. This approach attempts to determine the unique set of capabilities and values that are involved in (good) decisions in order to help people integrate those things into their own decision making processes, in accord with their own values, beliefs, needs, and responsibilities. To support practitioners (e.g., designers, psychologists, engineers), we also provide a theoretically grounded, practical checklist to compare the relative merits of different kinds of choice architecture (e.g., Libertarian Paternalistic versus Informed and Independent).

There are a few approaches you may want to consider for reading this book depending on your interests. For those who are interested in the theoretical and philosophical implications of the relation of personality with philosophical intuitions, you can safely read Chap. 6 alone (or at least start there). For those of you who are only interested in policy debates and ethical interaction design, you can skip directly to the last chapter. For those of you who are interested in evidence on the empirical findings about personality predicting philosophical intuitions, you can read Chaps. 2–5.

The primary goal of this book is to help provide a theoretical framework for understanding variation in fundamental philosophical intuitions, and to carefully consider how that variation may help promote the development of more ethical interactions. Along the way, we hope you will come to agree that it is no longer scientifically responsible or ethically defensible to treat all people as if they could or should normally have the same philosophical intuitions or values. Additionally, we hope you will see why we feel so strongly that people should not normally try to influence other people’s decisions without also giving careful consideration to diversity and disagreement in philosophical intuitions.