Jenann Ismael, a philosopher of physics, argues that free will is not only compatible with physics but is a natural consequence of how physics actually works—once you take relativity and thermodynamics seriously. Her account rejects the common assumption that classical determinism means the future is fixed from the beginning of time, and instead shows that reality is fundamentally incomplete from the perspective of any embedded agent. This incompleteness is not a limitation of knowledge but a logical feature of self-referential systems, and it is the physical ground for genuine agency.
The Failure of Determinism in Relativistic Physics
The standard argument against free will assumes Laplacian determinism: given the initial state of the universe and the laws of physics, everything thereafter is fixed. This is often taken to mean that human decisions are illusions—the outcome was already determined.
However, relativity undermines this picture. In a relativistic universe, predicting any event with certainty requires information from the entire past light cone of that event. But the past light cone of any event never contains enough information to determine the future with certainty.
Specifically, the contents of any past light cone can be embedded in indefinitely many models of the physical theory, each with different futures.
This is not a practical limitation—it is an in-principle impossibility, arising from the geometric structure of spacetime.
This means that even an ideal predictor, with perfect knowledge of the laws and the entire past light cone, cannot predict its own future behavior or that of any system it interacts with, if the prediction itself becomes part of the physical situation.
Self-Reference and the Limits of Prediction
The core technical insight comes from self-referential paradoxes, formalized in logic and computability theory (e.g., Gödel’s incompleteness, Turing’s halting problem).
Consider a device that tries to predict its own next output: if it says “yes,” it will do “no,” and vice versa. It cannot answer truthfully—not due to ignorance, but because of a logical fixed point in the representation relation.
This is not a contradiction in reality, but a demonstration that no system can fully represent its own state and future behavior from the inside without interference.
Ismael calls this negative interference: when a prediction or representation affects the system it describes, it can undermine its own truth. This is unavoidable for any embedded agent.
Thus, reality is incomplete not because we lack information, but because it is logically impossible for any part of reality to contain a complete representation of itself.
Thermodynamics and the Arrow of Causation
The thermodynamic gradient (the fact that the universe began in a low-entropy state) is essential for understanding time, causation, and life.
It creates records of the past (e.g., footprints, scars, smells) that carry information about prior events.
It also creates the need for living systems to metabolize energy to maintain their internal order against entropy.
Life evolves to exploit information in the environment to guide behavior:
Simple systems (e.g., magnetotactic bacteria) use hardwired responses to environmental cues.
More complex systems (e.g., frogs) process sensory information to trigger adaptive behaviors.
Humans go further: we store, curate, and reorganize information internally, forming plans, priorities, and a narrative sense of self over time.
The Self as a Self-Curating Information Structure
Ismael defines the self not as a soul or a fixed entity, but as a virtual object: a cognitively organized structure of information, supported by the brain but defined by its dynamic, self-referential organization.
The “I” refers to the subject of mental states, which is constituted by memories, beliefs, hopes, fears, and plans—all shaped by experience and reflection.
Over a lifetime, a person constitutes themselves through choices: what to read, who to trust, what to value. This is not passive reception but active self-construction.
When making a difficult decision (“dark nights of the soul”), the outcome is not determined by external factors alone. Instead, the agent organizes their priorities in the moment, drawing on a lifetime of curated information. The decision “comes from me” in a physically meaningful sense.
Free Will Without Breaking Physics
Ismael’s account does not require violating physical laws. Instead, it shows that determinism does not imply fatalism once relativity and self-reference are taken into account.
The future is not fixed in advance; it is open because no system can predict or determine its own future state without interference.
Human agency arises from the on-board information-processing machinery of the brain, which encodes a unique history of experiences and choices.
This view comports with folk intuition: when we say “I chose this,” we mean it drew on my values, memories, and deliberation—not that it was imposed from outside.
It also explains why loss is absolute: when a person dies, a unique, irreplaceable structure of information vanishes. Unlike patterns that might persist in others (as Hofstadter suggests), the inner world of the individual is irretrievably lost.
Time, Becoming, and the Block Universe
Ismael rejects the block universe (the view that past, present, and future all exist equally) as a useful but ultimately misleading picture.
While spacetime models are formally consistent, the idea of a “totality of all facts” is a mirage—it cannot be coherently defined due to self-referential paradoxes (e.g., Russell’s paradox).
From the inside, time is experienced as coming into being, not as a fixed landscape being revealed. This is not subjective illusion but a consequence of the interference between representation and action.
The arrow of causation arises from the thermodynamic gradient: interventions (actions) have probabilistic effects only on the future, not the past. This breaks the symmetry of physical laws and grounds the direction of time.
Consciousness and the Mind
Ismael distinguishes between mind (as a virtual machine that guides behavior) and phenomenal consciousness (the “hard problem” of subjective experience).
Free will, as she defines it, does not require phenomenal consciousness. It depends on information processing, self-representation, and goal-directed behavior—all of which can be physically realized.
Physics should care about minds because they move matter: cars, houses, and conversations exist because of mental activity. Minds are part of the causal structure of the world.
Newcomb’s Paradox and Causal Asymmetry
In Newcomb’s problem, a predictor places money in a box based on a prediction of your choice. You must choose one box or two. The paradox arises because your choice is correlated with the prediction, but there is no causal link (the prediction is made before you choose).
Ismael resolves this by grounding causation in intervention: causal relations are probabilistic correlations between actions and outcomes, screened off by the thermodynamic arrow. In Newcomb’s setup, the correlation is real but non-causal because it lacks the right temporal and intervention structure.
Personal and Philosophical Impact
Ismael’s work has changed her view of mortality and loss: every person is a unique informational structure, and death is an absolute, irretrievable end.
She emphasizes humility and openness in intellectual life: insight comes from diverse approaches, not from reinforcing existing paradigms.
A lesson from her advisor, Bas van Fraassen, reshaped her attitude toward suffering: much of it is optional, and letting go of external validation (status, success) can free one to pursue what truly matters.
Key Takeaways (Implicit in the Episode)
Free will is not an illusion—it is a consequence of the logical structure of relativity, thermodynamics, and self-reference.
The self is a dynamic, self-constructed information pattern, not a fixed entity.
Reality is incomplete from the inside, and this openness is the physical basis for agency.
Time’s arrow and causation arise from the thermodynamic gradient, not from fundamental laws alone.
Consciousness is not required for free will—what matters is the functional organization of information and behavior.
