Human figures with different things going on in their brains.
Chris Madden for Getty. 

How Who You Are Influences What You Think Is True

A new study found associations between psychological traits and philosophical beliefs. If who we are drives our philosophy, what does that say about our explanations of the world?

It's perhaps not surprising that there are competing philosophies for life's greatest mysteries, but a more intriguing question is this: Why is it that one person gravitates to a particular view and not another? What is it that brings a person to believe in free will, for example, and another to determinism? 

This is a longstanding question in philosophy, which has generated friendly disagreement between David Yaden, a postdoctoral research fellow at Johns Hopkins University School of Medicine, and Derek Anderson, a philosophy lecturer at Boston University, since they were college roommates. As a psychologist, Yaden felt that people's individual personalities held major influence, and could help explain why he observed certain people drawn towards certain philosophical beliefs. Anderson, a philosophy major, "wanted to stick up for philosophy.”


In a new paper published in Philosophical Psychology, Yaden and Anderson put their debate to the test. They asked 314 professional philosophers about their philosophical views, and then assessed psychological factors like personality, mental health, and life experiences, along with demographics, to see if there were any meaningful associations. 

They found that there weren't any significant correlations between demographics or personality and specific philosophical views, but they did find that certain psychological traits lined up with philosophical beliefs in interesting ways. For example, "theism" was associated with agreeableness. Lower life satisfaction and depression were associated with hard determinism, or not believing in free will. Having "subjectivist views" of aesthetics and morality—meaning that a person thinks that each individual has their own sense of beauty or morality—was associated with prior marijuana and psychedelic use. People who believed  that "philosophical zombies" could exist (a biological entity that functions just like a human, but with no consciousness) were more conscientious. 


The authors said that their findings further opens the door to study of the psychology of philosophy. This field will ask what psychological traits and past experiences might unduly influence our philosophical views, and crucially, what that says about our explanations of the world around us. Motherboard talked with Yaden and Anderson about their findings, and how who we are might affect our search for truth. 

This conversation has been lightly edited for length and clarity. 

Motherboard: There’s an Iris Murdoch quote I like a lot: “To do philosophy is to explore one’s own temperament and yet at the same time to discover the truth … It is always a significant question to ask about any philosopher: what is he afraid of?”

I first heard it while listening to a podcast called Five Questions, by Kieran Setiya, where he asks philosopher’s questions about themselves, not necessarily about their philosophical views—but with the implication that the two are inevitably intertwined. This is clearly an ongoing question: how much a philosopher’s identity or temperament influences the way they see the world. I wanted to start by asking both of you about when your interest in this topic piqued—as I understand it goes quite far back into your friendship!
Derek Anderson:
It does go back far! It’s one of the things I like most about this project. We have been thinking about this issue and arguing about it for a long time. Are my deepest philosophical beliefs about things like free will and consciousness really the result of my fears, desires, or personality, more than my rational thought processes about these things?


David Yaden: I like that Iris Murdoch quote! I’ll also have to check out that podcast. The question of how temperament impacts one’s philosophical beliefs—and vice versa—is not new. We are actively trying to compile historical and contemporary work on the topic, so we appreciate the references.

We have been friends since elementary school, but our interest in this topic began in our undergrad years at Rutgers where I was a psychology major and Derek was a philosophy major. At that time at Rutgers, philosophers there like Steven Stich and Josh Knobe were laying the foundations of a field called experimental philosophy, which uses tools from psychology to examine how people differ on philosophical thought experiments. While our focus is different, this must have influenced our thinking.

DA: I don’t think Knobe’s X-Phi Manifesto was on my radar yet when it came out, when we were seniors in 2008. But you’re probably right it was influencing us—unconsciously, maybe? Because it was definitely in the air at the time.

DY: Yes, the interest felt like it got sparked way more organically. We were in philosophy club and cognitive science club, and in both we had sometimes heated philosophical debates with other members. We were all students still learning the arguments and evidence, so why did our classmates feel so immediately and strongly attracted to one view over another? This goes for technical debates, but also the kinds of topics that come up in conversation for lots of people—like freewill, god, or whether morality and aesthetics are subjective or objective.


DA: This also goes back to our old disagreement. David, always the psychologist, was already thinking these strong attachments had more to do with personality than serious philosophical thought. I wanted to stick up for philosophy! But, of course, I was also afraid maybe he was right.

DY: Later, when Derek was getting his PhD in philosophy and I was getting a PhD in psychology, philosophers David Chalmers and David Bourget launched a famous survey of professors of philosophy called the PhilPapers Survey to see what views philosophers at top programs tend to hold.

DA: David (Yaden, not Chalmers) realized this big sociological study of philosophers—published in 2013 as “What Do Philosophers Believe?”—could open the door to empirically testing our old worries. If we re-created the same survey, but this time attached a battery of psychological tests, maybe we could determine scientifically whether philosophers’ beliefs were really predictable on the basis of their personality or other psychological factors.

DY: During and after grad school, we launched the same survey with the addition of psychological measures so that we could see what psychological traits predicted what philosophical views. That paper was just published.


Watch more from VICE:

Motherboard: Before we talk about what correlations you did find, let’s talk about what you didn’t find: notably that demographics didn’t correlate with philosophical views. That’s amazing to me! What are your thoughts on that? Were you surprised? Do you feel like it warrants further investigation? 
This was surprising to both of us, I think. And really the jury is still out on this one.

DY: That’s right, we didn’t see a correlation between demographics and philosophical views in this sample. This definitely warrants further investigation, as we consider our study preliminary and exploratory. But it’s really important to understand something about statistical significance testing here: lack of evidence of an effect doesn’t actually provide evidence of no effect. So, while we were surprised that we didn’t observe any association between philosophical views and demographics, we should definitely wait for additional studies to draw any conclusions on this topic.

There’s a lively debate in the field of experimental philosophy about demographics and philosophical views between Stephen Stich and Josh Knobe. I’d recommend checking out Josh Knobe’s paper called “Philosophical Intuitions Are Surprisingly Stable Across both Demographic Groups and Situations”.

DA: It would be very interesting to know that our philosophical judgments are not predicted by demographic or social factors. As David says, we are not at the point where we can really make that conclusion as scientists. The fact that we looked and did not find evidence for the hypothesis is not the same thing as finding evidence against the hypothesis. This really can’t be overstated because it’s one of the main ways that people misinterpret scientific data. But the fact that we didn’t find correlations here is definitely suggestive of further important work that needs to be done to fill in this picture.


Motherboard: You also found that personality didn’t correlate with philosophical views, but that psychological traits did. What’s the difference between personality and psychological traits? 
“Psychological traits” is a broad term to describe any psychological tendency or process that is measurable and relatively stable in humans. Height and weight are examples of physical traits, whereas personality is one of many psychological traits. Personality is usually broken down into five dimensions: Openness to Experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism, [or the acronym] OCEAN.

We were also surprised that we didn’t find any correlations between personality and philosophical views. But again, it’s really important that in this context lack of evidence of an effect doesn’t actually provide evidence of no effect. This is another finding that we need additional studies to investigate before we draw any conclusions.

DA: The fact that we found correlations between psychological traits more broadly does suggest that this experiment was picking up on some real predictive factors, though. We were able to detect reliable correlations between philosophical beliefs and other features of psychology.

This opens the door to creating a predictive “psychology of philosophy,” a science understanding what, in psychological terms, makes people more disposed to accept various philosophical views.


DY: A “psychology of philosophy” could also look at the effects of various philosophical views on one’s attitudes, mood, and behavior. We see the psychology of philosophy as something like a new sub-field.

Motherboard: Tell me a bit about the politics findings. What philosophical views was leaning politically right associated with? 
In terms of politics, it looks like more right-leaning philosophers held what William James would call more “tender-minded” beliefs, such as a belief in God, free will, and non-physicalism. This is probably because politically right-leaning philosophers tend to be more religious.

DA: Meaning they are a bit more likely to believe there is more to reality than just the physical world, including God and the idea that we have a power to choose which exceeds what could be predicted from the physical laws of nature.

One other thing that was noteworthy from my perspective is that right-leaning political orientation is correlated with accepting the correspondence theory of truth. This is a theory that says truth is an objective property of our beliefs, an objective correspondence between belief and reality. The political left, especially the radical left, is often thought of as rejecting this view of truth in favor of a more post-modern perspective on which representations of reality are always fragmented, always a matter of socially situated interpretation, never objectively true. I have a book forthcoming with Palgrave MacMillan where I talk about why it’s important to adopt the correspondence theory for left-leaning political reasons, so this finding was interesting.


Motherboard: What are some of your favorite or most interesting correlations? The one I’ve seen people commenting on the most is how people who don’t believe in free will have more negative mental health. That’s kind of funny and sad at the same time. It reminds me of how William James wrote, "My first act of free will shall be to believe in free will," which helped with his depression. 
That was a striking finding. I can see why that resonates with people.

DY: I agree—that’s a finding that kept coming up in our discussions. In the paper, we make a big deal about how we can’t interpret the causality here. For example, in this case it’s important to bear in mind that mental health could impact the belief one adopts, or it could be that the belief one adopts impacts one’s mental health, or it could be some other variable impacting both. Maybe, for some philosophers (and remember it’s a relatively small effect), being more depressed seems to provide evidence that our actions are largely outside of our control. Also, maybe, for some philosophers, holding a deterministic view results in less well-being. It’s a finding that’s worth understanding better through follow-up research.

DA: I wouldn’t be surprised if both things are happening in some cases. You feel depressed and it makes you believe or feel at some intuitive level that your actions are ineffective and maybe this lends itself in some small way to thinking we don’t have free will at all, and then this thought—I have no free will—well it sure seems like that thought could make someone who is depressed feel more depressed. This is pure speculation though, since we haven’t tested the causal claim in any scientific way.


DY: My personal favorite finding might be that 68% of our sample of philosophers thought that the results of a study like ours would have philosophical value. As a psychologist, I knew the results would have some scientific value but I thought most philosophers would think the findings would be irrelevant to their interests. Of course, it may have been that only philosophers who thought that such a study could be valuable would take our survey to begin with.

DA: I think the findings about transformative, self-transcendent, and religious experiences were some of my favorite findings. These findings were not really surprising to David; he predicted them on the basis of previous work. For example, having had a religious experience strongly predicts belief in God, and also predicts that you will reject the belief that all things are physical. This was one of the strongest effects we found. I think it also brings out something that is not decided by our study. Does a person who has a religious experience get new evidence that God really exists? Or is it just something happening in their own subjective experience?

In doing psychology of philosophy, scientists would not be trying to use data to answer the big question of whether God exists. We are only looking at how psychological factors—such as having had the experience—impact the person’s beliefs, not whether those beliefs are justified or true.


Motherboard: Can you explain what you found regarding the use of psychoactive substances like psychedelics and marijuana? David—you study psychedelics at Johns Hopkins, do you feel like these insights are complementary to the work being done on psychedelic assisted therapy for various mental health conditions? 
Yes, I study psychopharmacology now—especially psychedelics—at Johns Hopkins. Some surveys of the normal population done by myself and Roland Griffiths in years past found that psychedelic use was associated with spiritual-type beliefs. But we didn’t find that in this sample of philosophers. There are still so many open questions regarding psychedelics as well as their use as psychiatric treatments, especially the extent to which cultural expectations and beliefs relate to these experiences. I have several studies related to beliefs and psychedelics currently in the works.

I would not have predicted our finding that philosophers who used psychedelics and marijuana would have more subjectivist views of aesthetics and morality. My wife (a psychiatrist) offered one interesting interpretation: If someone is under the influence of a drug, then they might see something common, like a houseplant, as breathtakingly beautiful —but then the next day, when they are not on the drug, as mundane and nothing special. This experience might show the person that the appreciation of beauty can differ across different mental states, which might then lead someone to realize that big differences of aesthetic appreciation could exist between different people. It wouldn’t be much of a jump from there to accepting a subjectivist view of aesthetics.


Motherboard: Tell me more about “philosophical zombies” and what traits are correlated with that. 
A philosophical zombie is a strange concept that comes up in the philosophy of mind. When we ask how does consciousness exist in a physical system like a brain, we are faced with certain deep puzzles such as: why is anything conscious at all? Why does a brain produce or embody consciousness? One famous thought experiment from David Chalmers focuses on whether we can imagine a being who is physically identical to a human, but who has no subjective experience at all. They are like a biological machine that operates exactly like an ordinary human but with no consciousness there. You would not be able to tell by any external measurements that you are talking to a philosophical zombie. If it is possible for a zombie to exist, then consciousness cannot be identical with any physical property, because the zombie has all the physical properties of a regular human but lacks consciousness. The zombie thought experiment is part of an argument for dualism, or the view that mind is not entirely physical.

Strangely, we found a correlation between believing that zombies are possible and conscientiousness, which is a personality trait that has to do with wishing to do one's work diligently and thoroughly. In a way, this presents a very interesting scientific finding, because we really have no intuitive idea why this correlation should exist. We really have no idea what’s going on here.


DY: Because we were looking at so many variables, we adopted an extremely strict threshold for what is considered statistically significant. Despite that strict threshold, some findings may simply be noise, and I personally suspect this is one. We will see if it replicates in future studies. If it does replicate, it will be an interesting finding to try to explain.

Motherboard: What do your findings, or even this type of study, tell us about “knowledge” more generally? It may make a reader feel like there’s no such a thing as capital-T Truth out there, but instead there are many differing truths depending on what your psychological traits and life experiences are. Is that an interpretation that resonates with you?
I am a philosopher who thinks a lot about capital-T Truth, so you are really in my wheelhouse with this one! You’re raising two very important questions here. The first is, if we fundamentally disagree with others and our disagreements can’t be resolved to either of our satisfaction, does that mean there is no objective reality at all? And secondly, now that we are starting to measure these disagreements as potentially arising from factors that might be outside of our rational fact-gathering mind and tied instead to psychological factors that don’t really have anything to do with what is True, how can we trust our own faculties for judging The Truth?

These are the subject of ongoing philosophical dispute—and we are talking thousands of years, here—but I will give you my take. The fact that two people disagree about something does not mean there is no reality or that no one is correct in their view. One person might be correct and the other one incorrect, even if they are destined to disagree for some deep-seated reasons. This is why I think correspondence truth is crucial for political thought. The fact that one person is deeply committed to their view, so much so that they cannot be convinced otherwise, doesn’t show that they are right or that there is no reality at all. Similarly, we might believe things for reasons that don’t really provide a good guide to reality, for example if we believe in free will to avoid depression, but the fact that we might believe something for that kind of psychological reason doesn’t show there is no capital-T Truth about free will. But it might show that we have good reasons to interrogate our own beliefs in light of our psychological factors, which is what David and I have been thinking for a number of years.

Motherboard: On the other hand, of course our traits and life experiences influence what philosophy resonates with us. Do you feel this is essentially inescapable? That those factors will always influence a person’s interpretation of the world?
Well, I think what seems obvious here differs a great deal between people. Some philosophers have assumed temperament massively matters, whereas others have assumed it is almost irrelevant. Here, we provide some data that suggests that some aspects of psychology matter to some extent for some philosophical beliefs. I think this is a big step forward from an all or nothing kind of debate, to a debate that is informed by concrete scientific data.

DA: I think one way to put what you are saying, which I do think is essentially inescapable, is that everyone who has thought deeply about a topic has a very nuanced and complicated view of that topic that perhaps no one else shares. To say that I am a “physicalist” or that I am a “theist” is a label that we can use to empirically measure something common across individuals, but what is it exactly we are measuring? What is it that everyone who subscribes to that label has in common? Do any two people who are “theists” really believe exactly the same thing? Some philosophers who are skeptical of our general empirical program are worried about precisely this issue, that we can’t really measure what people mean when they use these simple terms.

Motherboard: How do you think this applies outside of philosophy? What about politicians or doctors or teachers? Is it important for us to know what kinds of traits influence their philosophies even if they’re not practicing philosophy, per se?
I think this project applies well outside of philosophy. A big part of our project was developing “translations” of these technical philosophical views into language that non-philosophers can understand. Derek and I went back and forth across hundreds of iterations of these and we pilot tested them in groups of philosophers and psychologists. The result is that we (and others) can now administer these non-technical philosophical questions to other professions as well as other people in general in future studies.

We partnered with Spencer Greenberg and his not-for-profit organization called ClearerThinking to develop an online test where people can answer these philosophical questions themselves. So if you would like to better understand your own personal philosophical views and how they compare to professional philosophers you can use the free Philosophical Beliefs tool.

DA: I also think the overall finding that some psychological factors predict our deepest and most important beliefs does give us some reason to pause and reflect on why we believe the things we do. What are the reasons we hold to our most central principles and deep-seated beliefs about reality? This is a good question for everyone.

Motherboard: Do you think that philosophers will be resistant to your findings? Meaning, is there a general assertion that when a person does philosophy they’re acting in “unbiased” ways and therefore not being influenced by temperament? 
Definitely. That kind of unbiased, objective thinker is an ideal for philosophers. There are actually strong philosophical arguments to back up the philosopher who believes their own psychology is totally irrelevant to the force of their arguments. But I think this kind of resistance you are talking about, being resistant to interrogating the ways that bias could infiltrate philosophical thought processes, runs very deep.

DY: I think most philosophers would argue that our results are irrelevant to the task of developing arguments … and I think they’re largely right. On the other hand, we did find that on average some philosophical views are associated with some psychological traits to some extent. Assuming most of these results replicate in future studies, I think they require psychological and philosophical explanations. One take-away that I like from all of this is that we have provided a new empirical, psychological, and quantitative component to the old Delphic maxim from the time of Socrates, to “know thyself.”

Follow Shayla Love on Twitter.