Bernal Argued in 1929 That a Synthetic Brain Cell Would Preserve Consciousness
The World, the Flesh and the Devil
J. D. Bernal's 1929 book states that replacing an organic brain cell with a synthetic apparatus would not destroy the continuity of consciousness.
J. D. Bernal stated in 1929 that replacing an organic brain cell with a synthetic apparatus “would not destroy the continuity of consciousness”. The claim sits in The World, the Flesh and the Devil: An Enquiry into the Future of the Three Enemies of the Rational Soul (Jonathan Cape, 1929), a short speculative book by a physicist then lecturing in structural crystallography at Cambridge. It is the gradual replacement argument, written out as a procedure fifty nine years later. Bernal arrived at it by treating the human body as an engineering constraint rather than a given.
The three enemies, and where the phrase comes from
The subtitle is not original to Bernal. “The world, the flesh and the devil” is a piece of Christian hamartiology, recorded in Latin as mundus, caro, et diabolus, and singled out by sources running from Thomas Aquinas to the Council of Trent as implacable enemies of the soul. The three are read as three sources of temptation. The world is indifference to God’s design. The flesh is disordered passion. The devil is the fallen angel. The phrase entered English through the Litany of the Book of Common Prayer, which asks deliverance “from al the deceytes of the worlde, the fleshe, and the deuill”.
Bernal was an atheist and a Marxist. He keeps the theological subtitle and reassigns all three named enemies to engineering. The book runs to six parts. The Future opens it. The World, The Flesh and The Devil take one enemy each. Synthesis and Possibility close it. The structure is the argument. Each enemy stops being a moral category and becomes a constraint with a design response.
| Enemy | Reading from Aquinas to the Council of Trent | Bernal’s reading | Part of the book |
|---|---|---|---|
| The World | Indifference and opposition to God’s design | The physical environment, including the gravitational field of the Earth | The World |
| The Flesh | Disordered passions and corrupt inclination | The body as a skeletal and metabolic constraint on the mind | The Flesh |
| The Devil | A real, personal enemy, a fallen angel | Motive and desire, the psychology that decides whether work gets done | The Devil |
The move is the reason the book is worth reading on consciousness rather than as period prophecy. Bernal does not argue that the soul survives the body. He argues the body is the wrong shape for the work the mind is doing.
The World, and the first design for a habitat in free space
Bernal’s opening move is gravitational. He writes that “the vast importance of escaping from the earth’s gravitational field has been almost entirely overlooked”, and that space travel should be judged by what leaving the field enables rather than by what visiting a planet delivers. On the rocket he is precise and correct. The difficulty “is simply that of projecting the particles, whose recoil is being utilized, with the greatest possible velocity, so as to economize both energy and the amount of matter required for propulsion”.
From there he specifies a permanent settlement. His words are worth quoting, because the dimensions are usually misreported. “Imagine a spherical shell ten miles or so in diameter, made of the lightest materials and mostly hollow.” The bulk of the material comes from “one or more smaller asteroids, rings of Saturn or other planetary detritus”, with only a small part lifted from Earth. An interior eight miles across “would contain as much effective space as a countryside one hundred and fifty miles square”. Power comes from a chlorophyll analogue that resynthesises carbohydrate from carbon dioxide, or from an electrical absorber with “vast, tenuous, membranous wings” to raise the collecting area. The habitat keeps “continuous communication by wireless with other globes and with the earth”.
That spherical shell is the object now called the Bernal sphere. Gerard K. O’Neill refined it at Stanford in 1975 and 1976 as Island One. It is the first worked design for permanent residence in free space, and it is why this section of the book belongs on the consciousness to orbit page, which tracks the claim that mind does not need a planet. Bernal is the earliest author on that page’s subject to give dimensions, materials and a power budget. The book is listed on the AI consciousness reading list as the oldest affirmative case in the set.
The design has a second function in the argument. Once the habitat exists, the body’s remaining excuses are gone. Bernal closes the section by noting that in this environment “man himself would have changed radically”, and hands the question to the next part.
The Flesh, and the cylinder that holds a brain
This is the part that carries the consciousness claim. Bernal starts from a cost accounting of the body. He writes that modern machinery and chemistry “have rendered both the skeletal and metabolic functions of the body to a large extent useless”, and that in a mechanised worker “the limbs are mere parasites, demanding nine tenths of the energy of the food”. The direction he draws is blunt. “Sooner or later the useless parts of the body must be given more modern functions or dispensed with altogether.”
He then sets out the design, and he states his own evidential status before he starts. “The account I am about to give must be taken rather as a fable.” Two preliminary claims anchor it. The first is that the brain is the load bearing organ. “After all it is brain that counts, and to have a brain suffused by fresh and correctly prescribed blood is to be alive, to think.” He reports that isolated perfusion “has already been performed on a dog and that is three quarters of the way towards achieving it with a human subject”. The second is the interface. “Already we know the essential electrical nature of nerve impulses; it is a matter of delicate surgery to attach nerves permanently to apparatus which will either send messages to the nerves or receive them.”
The resulting object is a rigid cylinder. Bernal’s own description is exact. “Inside the cylinder, and supported very carefully to prevent shock, is the brain with its nerve connections, immersed in a liquid of the nature of cerebro-spinal fluid, kept circulating over it at a uniform temperature.” An artificial heart, lung and digestive system feeds it oxygenated blood through the original arteries and veins, arranged so that any single organ can be exchanged without interrupting supply. He writes that the brain is “thus guaranteed continuous awareness”. The original eyes and ears stay attached to an optical box feeding periscopes, telescopes, microscopes and “a whole range of televisual apparatus”, with microphone attachments on the ear and chemical sense organs on the skin nerves. Manipulators are built “like that of a crustacean”, from micro-manipulators up to levers, with self repairing organs to service the rest.
| Design element | Bernal’s specification | Status of the claim |
|---|---|---|
| Life support | Artificial heart, lung and digestive system feeding the brain’s own vessels | Perfused isolated mammalian brain was demonstrated; long term human support was not |
| Interface | Nerve endings attached permanently to electrical send and receive apparatus | Directionally right; no channel count or bandwidth is given |
| Sensing | Optical box with periscopes, telescopes, microscopes and televisual apparatus | Correct in kind; the sensory substitution literature now covers part of it |
| Manipulation | Crustacean type appendages, micro-manipulators to levers | Matches modern prosthetic control research |
| Identity | Continuity of awareness maintained throughout | Asserted, not argued |
The claim that came fifty nine years early
Bernal’s sentence is short and it is the reason the book belongs in this argument. “Even the replacement of a previously organic brain cell by a synthetic apparatus would not destroy the continuity of consciousness.” He reaches it at the end of a passage on the compound mind, and he applies it in one direction only. If a cell can be exchanged without breaking awareness, then a brain can be reassembled from synthetic parts over time and remain the same mind.
Hans Moravec made the same claim in Chapter 4 of Mind Children in 1988 and gave it a procedure. A robot surgeon inspects one biological neuron, builds an electronic simulation matching its input output behaviour, switches the incoming and outgoing synapses to the substitute, and discards the cell. The subject stays awake. Moravec argued that because perception never lapses, neither does consciousness. The analysis of the Moravec transfer on this site sets out three assumptions the procedure rests on. Functional abstraction holds that a neuron contributes only its input output signalling. Organisational invariance holds that preserved organisation preserves experience on any hardware. Personal identity holds that continuous transition preserves the same subject.
None of those three appears in Bernal. He has the conclusion and no premises. The gap is not a defect in the 1929 book, which announces itself as a fable. It does mean that the claim in the sentence cannot be read as evidence for continuity. It is a statement of the position, published fifty nine years before the best known argument for it.
The same part of the book contains a second identity claim that is usually missed. Bernal describes a compound mind in which component brains are linked electrically and replaced as they die. He writes that the whole would be immortal, “the older component as they died being replaced by newer ones without losing the continuity of the self, the memories and feelings of the older member transferring themselves almost completely to the common stock before its death”. He adds that “identity and continuity of individual development would not be lost”. This is a group answer to the personal identity problem. It is a different answer from the branch line case in Derek Parfit’s Reasons and Persons, and it is closer to the merged mind scenarios the uploading literature now calls coalescing. The phrase “almost completely” is carrying the whole weight of the identity claim and Bernal does not examine it.
The Devil, which Bernal treats as the hardest constraint
The third part is the one he finds most resistant to engineering. His framing is explicit. “Because we can abandon the world and subdue the flesh only if we first expel the devil, and the devil, for all that he has lost individuality, is still as powerful as ever.” And, “The devil is the most difficult of all to deal with, he is inside ourselves, we cannot see him.”
He is honest about the state of the field he is relying on. “Psychology at the present day is hardly in a better state than physics in the time of Aristotle.” He uses what he has, including the Freudian division into id, ego and super ego, and he reaches two conclusions that hold up. Specialisation will slow research unless knowledge is distributed deliberately. And whether a society produces original work is decided more by desire than by capacity.
That ordering is the unexpected part of the book. Physics is the easy constraint. The body is tractable. Motivation is the binding limit on the programme, and Bernal puts it last on purpose.
Comparison to The Consciousness AI
Bernal’s claim is architecturally relevant to this project in one specific place. The project treats the organisation of a system, rather than the material that runs it, as the carrier of mind. Its Global Workspace layer, its Affective Core and the AKOrN binding that holds representations together are all functional organisation. On that much Bernal and the project agree, and Bernal states the agreement in 1929 without a theory behind it.
The step Bernal takes without argument is the one the project has not taken either. Continuity across component replacement is an open design question here, not a demonstrated property. Nothing in the codebase shows that a system remains the same system while its parts are exchanged. Bernal’s sentence is a design goal and it should be read as one.
His interface proposal has a firmer standing. He wants undifferentiated nerve connections that can be given new end organs at will, which is a claim about a separable interface rather than about a dedicated sensory surface. The project’s substrate work asks the same structural question, whether the organisation that carries a mind can be specified independently of the channels that feed it.
What the 1929 argument still requires
Bernal’s own hedge is the correct summary. He calls the account a fable, and he says that surgery and physiology “are sciences still too young to predict exactly how this will happen”. Three gaps stand between the fable and a claim about consciousness.
The book has no account of how organisation produces experience. It asserts continuity across replacement and gives no mechanism for it. That is the hard problem, and the book does not approach it.
The book does not separate copying from continuing. Bernal’s procedure is replacement, so his case is the gradual one. He never considers a scan and copy case, and the objection that a copy is a different person cannot be stated in his terms.
The book’s technical record is mixed in a way worth stating. Molecular architecture of materials, synthetic food and the general shape of a rocket problem are close to what followed. The ten mile sphere is unbuilt. And Bernal offers, as he puts it “it may be that”, a device called Japolsky’s magnetofugal waves as a possible solution to both space travel and energy transmission. He marks it as a possibility and it should be read as one.
One note on how to weigh the author. Bernal’s later public record includes his defence of Trofim Lysenko’s genetics, which cost him standing among biologists. That does not touch the 1929 argument. It does mean his speculation should be checked line by line rather than taken as a whole.
What survives in Bernal is a formulation rather than a proof. He names the constraint, he names the design response, and he states the continuity claim that the Moravec transfer would later try to justify. The end state he reaches in the final paragraph is also worth stating, because it is the one Tsiolkovsky reached by a different route. Humanity becomes “completely etherealized”, then “masses of atoms in space communicating by radiation”, and finally “perhaps resolving itself entirely into light”. The analysis of Tsiolkovsky’s cosmic eras records the same destination reached through panpsychism. Bernal gets there in 1929 through engineering, without claiming that atoms feel. That is the cleaner path, and it is the earlier one.
The World, the Flesh and the Devil: An Enquiry into the Future of the Three Enemies of the Rational Soul by J. D. Bernal was published by Jonathan Cape in 1929. The full text is held in the J. D. Bernal Archive at marxists.org. An Indiana University Press edition with an introduction by Arthur C. Clarke appeared in 2001. Arthur C. Clarke called the book “the most brilliant attempt at scientific prediction ever made”, and Robert Scholes called it “probably the single most influential source of science fiction ideas”. Bernal (1901 to 1971) was a Fellow of the Royal Society and Professor of Physics at Birkbeck College, University of London, from 1937.
