Books about digital immortality tend to fall into two categories. The first is the uncritical enthusiasm genre, where mind uploading is treated as an imminent engineering problem awaiting sufficient compute. The second is the philosophically sophisticated dismissal, where the concept is declared conceptually incoherent before the technical realities are fully engaged. Tobias Arendt-Lowe’s “Digital Immortality,” published in February 2026, occupies neither position, and that is its most significant feature.

Arendt-Lowe is a philosopher with a secondary background in cognitive science, and the book reflects this dual training. He is willing to engage with the neuroscience literature on its own terms, and he is equally willing to note when technical arguments quietly smuggle in philosophical assumptions that require separate justification. The result is a book that makes a serious attempt to evaluate mind uploading without pre-deciding the verdict.

The book is not a research paper. It is a considered argument for a general academic audience, and some of the technical discussions are necessarily simplified. For readers working in connectomics or computational neuroscience, the simplifications will occasionally frustrate. The philosophical scaffolding, however, is worth the time.

What the Book Argues

Arendt-Lowe’s central claim is that the mind uploading debate cannot be resolved through technical arguments alone because it rests on a prior metaphysical question that technical progress cannot settle: what kind of thing is the mind?

If the mind is identical to a particular pattern of information processing, then in principle the pattern can be extracted from biological hardware and instantiated elsewhere. Technical progress may make this difficult or easy, but it does not change the logical structure of the claim. If, on the other hand, the mind is not identical to information processing but depends on features of biological tissue that cannot be abstracted away, then no amount of computational sophistication will produce a genuine mind upload. It will produce a functional imitation.

Arendt-Lowe calls this the “substrate question” and argues it is the book’s central problem. His position is that neither philosophical functionalism nor biological naturalism has resolved the substrate question, and that current confidence in either direction is unwarranted given what the science does and does not show.

The Technical Picture Arendt-Lowe Draws

One of the book’s more useful contributions is its survey of the technical distance between current capabilities and the requirements for credible mind uploading. Arendt-Lowe is honest about the gap in a way that popular treatments often are not.

He correctly identifies that whole brain connectome mapping at human scale does not exist, that preserving synaptic dynamics alongside structural connectivity is a harder problem than preserving connectivity alone, and that running a realistic simulation of a human-scale connectome is not currently possible even with the most powerful available hardware. These observations are accurate as of the time of writing and reflect a reading of the literature that is appropriately cautious.

The book’s technical narrative has an endpoint that is worth noting: Arendt-Lowe does not claim these problems are unsolvable. He treats them as serious engineering challenges whose solutions are plausible in principle but are not close in practice. The 2025-2026 reality check on mind uploading that has circulated in the academic literature reaches similar conclusions from a more technical direction.

Where the book’s technical discussion is less careful is in its treatment of consciousness. Arendt-Lowe accepts, without extensive argument, that current AI systems are not conscious. This may well be correct, but it is a position that requires more support than the book provides, particularly given the active research on frameworks like the Digital Consciousness Model that are attempting to benchmark AI consciousness systematically.

The “Soul” Debate

The book’s title points to its most contentious section. Arendt-Lowe spends three chapters engaging with the possibility that something about human mentality resists computational capture, not necessarily in a religious sense, but in a broader metaphysical sense that includes secular philosophical positions such as biological naturalism (John Searle), phenomenal consciousness theories (David Chalmers), and enactivist views that emphasize the role of the body in generating experience.

He calls this the “soul” debate not to endorse theological claims but to mark the class of arguments that hold that minds are not reducible to computational patterns. He engages these seriously rather than dismissing them as residual superstition.

The strongest version of this argument, which Arendt-Lowe presents fairly, is that functional equivalence does not entail experiential equivalence. A system that processes information identically to a brain may produce identical behavioral outputs without producing identical subjective experience. If subjective experience is what matters for personal identity and for what we care about when we talk about preserving a mind, then functional replication is not sufficient.

This argument is not novel, but Arendt-Lowe’s presentation of it is clean. He connects it to the philosophical treatment of consciousness continuity and to the personal identity literature in ways that make the implications concrete.

Where the Argument Is Strongest

The book is at its most persuasive when it insists that technical feasibility and philosophical adequacy are separate questions. Researchers and engineers in the WBE field sometimes write as if demonstrating that a high-fidelity brain simulation can be run is equivalent to demonstrating that the simulation would constitute the person whose brain it was modeled on. Arendt-Lowe correctly identifies this as a logical gap.

Even granting that a perfect structural and functional replica of a brain could be produced, questions of identity persistence, psychological continuity, and the relationship between information patterns and subjective experience remain open. These are not questions that neuroscience alone can close, because they are partly constitutive questions about what we mean by “the same mind” rather than empirical questions about what brains do.

The designing ethical digital ghosts literature has engaged with related questions from a different angle, focusing on the ethics of posthumous digital representations. Arendt-Lowe’s book adds philosophical depth to that ethical terrain.

Where the Critique Falls Short

The book’s weakest sections involve its implicit assumptions about what “soul” or non-reducible mental properties would actually consist of. Arendt-Lowe is eloquent about the possibility that such properties exist but is considerably less precise about what they would be and how one might detect their presence or absence.

If non-reducible mental properties exist, they must have some causal role in producing behavior, or they are epiphenomenal and irrelevant to the questions we care about. Arendt-Lowe does not engage with this dilemma seriously. He acknowledges epiphenomenalism as a position but sets it aside rather than refuting it. This leaves the “soul” side of the debate underspecified.

The book also underestimates the extent to which philosophical functionalism has already engaged with the objections he raises. The response to the “mere simulation” critique within functionalist philosophy of mind is sophisticated and not easily dismissed. Arendt-Lowe presents the objection clearly but does not engage with the strongest functionalist replies in comparable depth, which gives the soul-debate chapters an asymmetric quality.

The treatment of digital afterlife ethics is also thinner than the philosophical framing would lead one to expect. Given that the book is explicitly engaging with immortality as a goal, the absence of sustained engagement with the ethics of seeking radical life extension is a gap.

What Researchers Should Take From It

For researchers in connectomics, computational neuroscience, and whole brain emulation, Arendt-Lowe’s book is useful not as a technical resource but as a calibration tool. It models how someone with genuine philosophical training reads the field’s technical claims, and the questions it raises are ones that serious WBE projects need to have considered answers to.

The substrate question is not going to be resolved by building a better simulation. It requires a prior theoretical commitment about what minds are, and that commitment should be made explicit rather than assumed. The Springer Nature volume on ethics in transhumanism approaches related questions from a normative direction. Arendt-Lowe approaches them from a metaphysical one. Both are worth reading alongside the technical literature.

The book’s honest account of the technical gap is also a reminder that the engineering problems in WBE are not peripheral to the philosophical debate. They are central to it. A world in which high-fidelity brain emulation is technically feasible is one in which the philosophical questions become urgent in a different way than they are today. Arendt-Lowe’s contribution is to begin preparing the philosophical vocabulary before that urgency arrives.

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Official Sources

• Arendt-Lowe, T. (2026). “Digital Immortality: Navigating the Soul Debate.” Published February 20, 2026.
• Searle, J.R. (1992). “The Rediscovery of the Mind.” MIT Press. (Biological naturalism framework)
• Chalmers, D. (1996). “The Conscious Mind: In Search of a Fundamental Theory.” Oxford University Press. (Phenomenal consciousness and the hard problem)
• Chalmers, D. (2022). “Reality+: Virtual Worlds and the Problems of Philosophy.” W.W. Norton. (Digital minds and functionalism)
• Sandberg, A. & Bostrom, N. (2008). “Whole Brain Emulation: A Roadmap.” Future of Humanity Institute. WBE roadmap overview
• Mindtransfer.me related analyses: Mind Uploading Reality Check 2025-2026, SOMA: Consciousness Continuity