The Big Picture
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lead to future adjustments in our credences, but right now naturalism is
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well out ahead of the alternatives.
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Science uses the strategy of empiricism, learning about the world by looking
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at it. There is a countervailing tradition: rationalism, the idea that we can
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come to true knowledge of the world by methods other than through our
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“Rationalism” sounds like a good idea; who doesn’t want to be rational?
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But this particular use of the word refers to learning about the world by
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reason alone, without any help from observation. There are a number of
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different ways it could happen: we could be equipped with innate knowl-
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edge, we could reason about how things are on the basis of incontrovertible
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metaphysical principles, or we could be gifted with insight through spiri-
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tual or other nonphysical means. A close look reveals that none of these is
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a very reliable way to learn about our world.
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None of us comes to life as a blank slate. We have intuitions, instincts,
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built-in heuristics for dealing with our environment, developed over the
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long course of evolution— or perhaps, one might believe, planted there by
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God. The mistake is to think of any of those ideas as “knowledge.” Some
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might be correct, but how would we know? Just as assuredly, some of our
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natural instincts about the world often turn out to be wrong. The only good
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reason we have for trusting any supposedly innate ideas is that we test them
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against experience.
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A related route to rationalism is based on the belief that the world has
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an underlying sensible or logical order, and from this order we can discern
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a priori principles that simply have to be true, without any need to check up 19
on them by collecting data. Examples might include “for every effect there
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is a cause,” or “nothing comes from nothing.” One motivation for this view
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is our ability to abstract from individual things we see in the world to uni-
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versal regularities that are obeyed more widely. If we were thinking deduc-
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tively, like a mathematician or logician, we would say that no collection
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of particular facts suffices to derive a general principle, since the very
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next fact might contradict the principle. And yet we seem to do that all the
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time. This has prompted people like Gottfried Wilhelm Leibniz to suggest
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that we must secretly be relying on a kind of built-in intuition about how
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things work.
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Perhaps we are. The best way of knowing whether we are is to test that
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belief against the data, and adjust our credences appropriately.
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John Calvin, an influential theologian of the Protestant Reformation, sug-
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gested that human beings possess an ability known as the sensus divinatis,
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a capacity to directly sense the divine. The notion has been taken up in
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contemporary discussion by theologian Alvin Plantinga, who goes on to
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suggest that the sense is shared by all human beings, but that it is faulty or
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silent in atheists.
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Is it possible that God exists, and communicates with human beings in
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ways that circumvent our ordinary senses? Absolutely. As Plantinga cor-
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rectly points out, if theism is true, then it makes perfect sense to think that 07
God would implant knowledge of his existence directly into human beings.
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If we are already convinced that God is real and cares about us, there would
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be good reason to believe that we could learn about God through nonsen-
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sory means, such as prayer and contemplation. Theism and this flavor of
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rationalism could, under these assumptions, be parts of a fully coherent
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planet of belief.
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What that doesn’t do is help us decide whether theism actually is true.
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We have two competing propositions: one is that God exists, and that tran-
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scendental experiences represent (at least in part) moments when we
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are closer to divinity; the other is naturalism, which would explain such
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experiences the same way it would explain dreams or hallucinations or
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other impressions that arise from a combination of sensory input and
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the inner workings of the physical brain. To decide between them, we
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need to see which one coheres better with other things we believe about
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the world.
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One way that inner, personal spiritual experiences would count as genu-
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ine evidence against naturalism would be if it were possible to demon-
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strate that such mental states— feelings of being in touch with something
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greater, of being outside one’s own body, dissolving the boundaries of self,
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communicating with nonphysical spirits, participating in a kind of cos-
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mic joy— did not, or could not, arise from ordinary material causes. Like
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many questions about consciousness and perception, this one is somewhat
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open, though there is an increasing amount of research that draws direct
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connections between apparently spiritual experiences and biochemistry in
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the brain.
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The author Aldous Huxley, in his nonfiction book The Doors of Percep-
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tion, describes his experiences with the psychoactive drug mescaline, in-
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cluding “sacramental vision.” Similar drugs, such as peyote and ayahuasca,
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have long been used to induce spiritual states, especially by Native
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Americans, and related effects have been noted in association with LSD
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and psilocybin (magic mushrooms). Huxley felt that
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enhance his consciousness, removing filters that shielded his mind from a
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greater awareness. He would return to psychedelics repeatedly in his life,
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including at the very end, when he asked his wife, Laura, to inject him with
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LSD to help alleviate the extreme pain caused by laryngeal cancer. After-
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ward, Laura reported that his doctors had never seen a patient with that
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kind of cancer, usually marked by violent convulsions, spend their final
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moments with so little pain and struggle.
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Recent neuroscience indicates that Huxley may have been on the right
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track about the filtering effects of mescaline. We tend to think of psyche-
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delics as stimulating visions and sensations, but work by Robin Carhart-
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Harris and David Nutt used functional magnetic resonance imaging
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(fMRI) to argue that these drugs actually work to suppress neuronal activ-
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ity in parts of the brain that act as filters. Some parts of our brain, it turns
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out, are constantly buzzing with images and sensations, which other parts
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then work to suppress in order to maintain the coherence of our conscious
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self. The detailed mechanism is unclear, but there are indications that some
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hallucinogens help activate a certain receptor for serotonin, a neurotrans-
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mitter that helps regulate our moods. Psychedelics, in this picture, don’t
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conjure up new hallucinations but simply allow us to consciously perceive
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what is already bouncing around inside our brains.
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It proves nothing about whether we also have feelings and visions as a
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result of a direct connection to a spiritual reality. Perhaps certain drugs
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have effects that mimic those of genuine transcendent experiences, without
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actually explaining them away. Perhaps, indeed, drugs or direct physical
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influences on the brain can open us up to such experiences and bring us
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into contact with a broader reality. On the other hand, there might be sim-
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ple and elegant explanations for transcendent experiences that don’t lean
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on a non- natural world in any way.
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Given the profound and deeply personal nature of prayer, meditation,
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and contemplation, it can seem frivolous or diminishing to relate them to
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psychedelics or the activity of neurons, or even to dispassionate scientific
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investigation of any sort. But if we want to undertake our journey to the
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best possible understanding of the world with the intellectual honesty it
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deserves, we always have to question our beliefs, consider alternatives, and
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compare them with the best evidence we can gather. It may be the case that
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transcendent experiences arise from a direct connection with a higher level
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of reality, but the only way to know is to weigh that idea against what we
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learn from the world by looking at it.
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Who Am I?
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A
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ll of this discussion about emergence and overlapping vocabularies
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and domains of applicability isn’t merely arid philosophizing. It
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cuts to the very essence of who we are.
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Consider an issue that is central to our self- conception: gender and sex-
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uality. As I am typing these words, societies across the world are going
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through dizzying changes in how they think about this topic. One indica-
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tion of the change is the shifting status of same- sex marriages. In the United
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States, the Defense of Marriage Act, which defined “marriage” as far as the
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federal government was concerned as the union of one man and one
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woman, was passed overwhelmingly in 1996. The House Judiciary Com-
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mittee affirmed that the act was intended “to express moral disapproval of
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homosexuality.” By 2013, the Supreme Court had declared that definition
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unconstitutional, so that the federal government would recognize same- sex
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marriages that had been sanctioned by any of the states; two years later, the
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Supreme Court found that it was unconstitutional for individual states to
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ban the practice, effectively legalizing it nationwide. Thus the United States
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caught up with Canada, Brazil, much of Europe, and other countries that
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had already legalized same- sex marriages. Meanwhile, there are still a large
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number of countries where same- sex relationships are subject to imprison-
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ment, even the death penalty.
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If marriage is a contentious issue, gender identity is even more chal-
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lenging. As social mores are changing, an increasing number of people who
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identify as a gender different from their biological sex are deciding to accept
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that aspect of who they are, rather than hiding it or fighting to suppress it.
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Some transgender people choose to undergo medical procedures to alter
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their anatomical makeup, while others do not; either way, their psycho-
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logical affiliation with the gender they identify with can be just as strong as
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that of “cisgender” people (those whose gender identity agrees with their
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biological sex). You will always remember the first time that a friend who
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you’ve known for years as a woman, and referred to using pronouns “she”
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and “her,” requests to be thought of from now on as a man, using pronouns
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“he” and “him.”
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After Ben Barres, a professor of neurobiology at Stanford, gave a well-
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received seminar at a conference, one of the scientists in the audience re-
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marked, “Ben Barres’s work is much better than his sister’s.” Except that
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Barres didn’t have a sister; the scientist was thinking of Barres himself, who
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had previously been a woman known as Barbara Barres. It was the same
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work that was being judged— it just seemed more impressive coming from
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a man. Our opinion of a person is greatly affected by what sex we perceive
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them to be.
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Whether you are forward- thinking about such things or staunchly tra-
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ditionalist, it can be a difficult transition to get used to. How can a person
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you know, or thought you knew, as a man, suddenly just declare that she’s a
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woman? That’s like deciding one day that you are eight feet tall. There are
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some things you just don’t get to decide; they simply are what they are.
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Right?
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Part of how we respond to people who are different from us depends on
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basic features of our own social orientation and frame of mind. Some peo-
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ple have a fundamental live- and- let- live attitude, or are committed social
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liberals, and make a point of accepting an individual’s right to declare who
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they are. Others tend to be more naturally wary or judgmental, and frown
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upon behavior that seems unconventional to them.
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But there is something deeper here than mere personal attitudes: there
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is a question of ontology. What categories do you take to “really exist,” to
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play a central role in how the world is organized?
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For many people, the concepts of “male” and “female” are deeply rooted
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in the fabric of the world. There is a natural order of things, and these con-
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cepts are an indelible part of it. If eliminativism is the urge to declare as
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many things illusory as possible, its opposite is essentialism: the tendency to 04
take certain categories as immovable features of the bedrock of reality. At