The Metaphysical Through the Lens of Harvard Research

In an earlier piece, I argued that metaphysics is reason pushed to its deepest horizon, not mystical thinking without discipline, but the rigorous study of what reality is, beneath what appears. That article drew mainly on the philosophical tradition: Aristotle, Kant, the structure of being, the mind-body problem, the question of free will. What I want to do here is push the same questions a layer deeper by looking at what researchers at Harvard, working at the seam between philosophy, neuroscience, and public health, are finding.

The metaphysical questions are not idle. What is consciousness? Is causation real? Can perception be rational? Does spiritual experience track something genuine, or is it an artifact of the brain? Harvard scholars have been answering these questions in ways that complicate easy materialism without surrendering scientific rigor.

Causation: More Than the Mind's Pattern

One of the oldest metaphysical puzzles is whether causation is a genuine feature of reality or simply a pattern human minds project onto regularities. Hume famously argued the latter. Contemporary metaphysicians have pushed back, and few more carefully than Edward “Ned” Hall, Norman E. Vuilleumier Professor of Philosophy at Harvard, whose work centers on the metaphysics of causation, the foundations of physics, and the structure of natural laws.

Hall’s co-authored book Causation: A User’s Guide (Oxford University Press, 2013) treats causation as a genuine philosophical problem rather than a settled scientific concept. His broader project, articulated in The Philosophy of Science: Metaphysical and Epistemological Foundations (Blackwell, 2014), is that science itself rests on metaphysical commitments; about laws, about what counts as a fundamental entity, about the relationship between the “scientific image” and the “manifest image” of the world (Harvard Department of Philosophy faculty page).

This matters for the metaphysical worldview I sketched previously. If causation is genuinely intrinsic to processes, not just a useful summary of regularities, then the universe has more structure than pure empiricism is comfortable admitting. Hall’s careful work shows that this structure can be defended without retreating from science.

Perception Is Not a Neutral Window

A second assumption that quietly shapes most worldviews is that perception simply delivers reality to us. We see the world; the world is more or less what we see. Susanna Siegel, the Edgar Pierce Professor of Philosophy at Harvard, has spent two decades dismantling this picture.

In The Contents of Visual Experience (Oxford, 2010), Siegel uses what she calls the method of phenomenal contrast to argue that we perceive far more than color, shape, and motion, we perceive causation, kinds, and personal identity directly. In The Rationality of Perception (Oxford, 2017), she goes further: perceptual experiences themselves can be rational or irrational, because they are shaped by prior beliefs, fears, and prejudices (Harvard Mind Brain Behavior Initiative profile).

The metaphysical implication is uncomfortable and important. If our experience of reality is already inferential, already shaped by what we expect to find, then naive realism, the idea that we straightforwardly know “what is”, collapses. This does not mean reality is unknowable. It means that any honest metaphysics must reckon with the fact that we do not encounter reality from a neutral, God’s-eye view. This is, incidentally, very close to the Kantian point I made in my earlier article, now updated with the tools of cognitive science.

Consciousness: The Hard Problem at the Bedside

Few metaphysical questions are as pressing as the nature of consciousness. In a recent Harvard Gazette piece, Joseph Giacino, Professor of Physical Medicine and Rehabilitation at Harvard Medical School, pointed out that there is no universally accepted definition of consciousness, and that clinicians treat it as a “dynamic, fluctuating” state rather than something with a clear on/off boundary.

What I find arresting is how Giacino describes the clinical reality. Studies of patients with disorders of consciousness show that if a single examination is performed, the diagnostic error rate is close to 40 percent — meaning roughly four in ten people pronounced unconscious are not. With five exams over two weeks, the error rate falls to about 5 percent. Giacino notes that the most common cause of death after severe brain injury is the withdrawal of life-sustaining treatment, leading him to a striking observation: few people die from brain injury; most die from treatment decisions (Harvard Gazette, December 2025).

Even more striking is research co-led by experts at Harvard-affiliated Mass General Brigham, published in the New England Journal of Medicine in August 2024. In a study of 241 patients with severe brain injury who appeared unresponsive, roughly one in four showed measurable cognitive responses to instructions when assessed with functional MRI or EEG, a phenomenon called cognitive motor dissociation (Harvard Gazette report on the study).

This is empirical evidence that consciousness can be present without any outward behavioral sign. It does not solve the philosophical “hard problem” of why subjective experience exists at all. But it does suggest that a purely behaviorist or surface-level account of mind is dangerously incomplete. The inner life is real even when the outer life is silent.

Free Will, Moral Responsibility, and the Brain

The free will debate, which I touched on earlier, has been transformed by the work of Joshua Greene, the Alfred and Rebecca Lin Professor of Civil Discourse and Professor of Psychology at Harvard. Trained originally as a philosopher, Greene uses neuroimaging to study how moral judgments are actually made, applying a dual-process framework that distinguishes “fast” automatic emotional reactions from “slow” deliberative reasoning. His lab has applied this framework specifically to beliefs about free will and punishment (Greene Lab research page).

Greene’s argument, developed in papers and his book Moral Tribes, is that neuroscience will not abolish the law’s reliance on responsibility, but it will gradually transform our moral intuitions about it (Greene’s academic profile). This is a philosophically interesting middle position. It accepts that moral psychology is implemented in physical brains while denying that this fact, by itself, makes responsibility an illusion.

For my own metaphysical question, whether human agency is a basic feature of persons or a useful fiction, Greene’s work suggests neither extreme is quite right. Agency is real enough to be studied, modulated, and held morally accountable. But the picture of an immaterial will operating outside the causal order is not what the brain shows us.

Spirituality, Meaning, and Health

The final question I want to revisit is whether the spiritual dimension of metaphysics has any empirical traction. It does, and Harvard’s Initiative on Health, Spirituality, and Religion, based at the T.H. Chan School of Public Health, is one of the most rigorous places in the world studying it.

Tyler VanderWeele, the John L. Loeb and Frances Lehman Loeb Professor of Epidemiology and co-director of the Initiative, has built a large body of longitudinal evidence connecting religious participation to better mental and physical health, lower mortality, greater life satisfaction, and stronger reported meaning and purpose (Harvard T.H. Chan School of Public Health Initiative page). A 2022 paper in JAMA, co-authored with Tracy Balboni and others, argues that spirituality should be integrated into clinical care for serious illness (Harvard’s Initiative on Health, Religion, and Spirituality summary). VanderWeele also leads the Global Flourishing Study, a multi-year, $43+ million project measuring well-being across more than 200,000 participants in 22 countries.

I want to be careful here. None of this proves any specific metaphysical claim; not the existence of God, not the reality of a soul, not the truth of any tradition. What it does show is that spiritual practice is not metaphysically inert. It correlates with measurable outcomes that any serious account of human flourishing must explain. Pure reductionism, which treats meaning making as epiphenomenal, has trouble accounting for why it works.

What This Adds to a Responsible Metaphysics

Looking across this Harvard-anchored body of work, a few things stand out for the kind of responsible metaphysics I argued for earlier.

First, science and metaphysics really are partners, not rivals. Hall’s work on causation, Siegel’s work on perception, Giacino’s clinical research, Greene’s neuroscience of moral cognition, and VanderWeele’s epidemiology of spirituality are all empirical projects that take metaphysical questions seriously rather than dissolving them.

Second, the case against simple physicalism has gotten stronger, not weaker.

Consciousness is more elusive than behaviorism allowed. Perception is more inferential than naïve realism allowed. Causation is more structural than Humean regularity allowed. Spirituality has more measurable consequences than reductionism allowed. None of this proves dualism, but it does show that the metaphysical questions I described, about mind, causation, agency, and meaning, are not going to be settled by a brisk appeal to “just the brain.”

Third, intellectual humility is the right posture. Diagnostic error rates of 40 percent in unresponsive patients are a vivid reminder that what we measure is not always what is real. Kant’s warning, which I emphasized in my earlier piece, becomes sharper when we see how easily our methods can miss what is right in front of us.

Conclusion

The metaphysical is not a domain we have outgrown. If anything, the closer we look at the brain, at perception, at agency, and at meaning, the harder it becomes to maintain that reality is exhausted by what is publicly measurable in any given moment. Harvard’s research does not give us a finished worldview. But it does keep open the deepest human questions in a way that respects evidence: What is real? What are we? What is consciousness? What does it mean to be free? And what, if anything, lies at the ground of being?

These remain open questions. That is exactly why they remain worth asking.

Sources Cited

•       Harvard Department of Philosophy, faculty page: Edward J. Hall (philosophy.fas.harvard.edu).

•       Edward J. Hall, The Philosophy of Science: Metaphysical and Epistemological Foundations (Blackwell, 2014); Causation: A User’s Guide with L.A. Paul (Oxford, 2013) (Wikipedia summary).

•       Susanna Siegel, The Contents of Visual Experience (Oxford, 2010); The Rationality of Perception (Oxford, 2017) (Harvard Department of Philosophy; Harvard MBB profile).

•       Sy Boles, “Consciousness,” interview with Joseph Giacino, Harvard Gazette, December 11, 2025 (news.harvard.edu).

•       “International study detects consciousness in unresponsive patients,” Harvard Gazette, August 2024, on Mass General Brigham research published in NEJM (news.harvard.edu).

•       Joshua D. Greene, Department of Psychology, Harvard University — research on moral cognition and free will (Harvard Psychology; Greene Lab).

•       Tyler J. VanderWeele et al., Initiative on Health, Spirituality, and Religion, Harvard T.H. Chan School of Public Health (Chan School; Initiative homepage).