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On David Hoffman’s Case Against Reality

A recently retired academic, with a background in psychology and philosophy.


What a sensible, straightforward story this one is: we perceive cars trains apples and bears because the world consist of, among other things, cars trains apples and bears. Of course, such objects exist even when we, or any other percipient organism, are not looking at them (or hearing, smelling, tasting, touching them, whatever the case may be).

Granted: our perceptual systems do not provide us with an invariably accurate representation of the external world. They do on occasion deceive us. Perceptual scientists have uncovered the many ways in which our senses can lead us astray by generating illusory percepts. And most of us have noticed that the moon appears larger on the horizon than at the zenith, for instance, or that after watching a waterfall for a while and then shifting our gaze to adjacent features of the environment, they appear to be moving upward, hence in a direction opposite to that of the falling water. Still, even allowing for their proneness to illusions, we trust our senses in our everyday life, and make numberless decisions based upon their input.

The fact that as a species we are still around to tell the tale is proof enough that our senses must be fundamentally veridical. For if they had provided us with a seriously wrong view of reality, evolution by natural selection would have weeded us out of this suffering planet long ago. Further, we can surmise that humans whose perceptual apparatuses were well attuned to the objective properties of the physical world had a better chance of surviving and passing on their genes to their offspring, than individuals perceptually less endowed.

David Marr (1945-1980), a MIT Psychology professor whose book on human vision (1982/2010) played a pivotal role in the development of computational neuroscience, subscribed in full to the view that our sensory systems usually ‘deliver a true description of what is there’, and that evolution progressively molded our perceptual apprehension of the world toward an increasingly accurate, albeit occasionally fallible, view of reality. This remains the dominant view of the perception-reality nexus among cognitive scientists.

Charles Darwin, 1830s.

Charles Darwin, 1830s.

Our Senses Lie to Us: For Our Own Good

Enter Donald Hoffman. A MIT graduate whose doctoral dissertation was supervised by Marr, Hoffman is a professor in the Department of Cognitive Sciences at the University of California, Irvine; he also holds joint appointments in the Departments of Philosophy; of Logic and Philosophy of Science; and in the School of Computer Science.

Author of numerous articles and books in his field, Hoffman has outlined his views perhaps most comprehensively in The Case Against Reality (2019).

His main thesis runs counter to the accepted wisdom. Our perceptual apparatus - and those of other species - was not shaped by evolution toward a progressively truer representation of the physical world. In fact, ‘perceiving truth would drive our species extinct’ (Hoffman, 2019, p.8). Evolution has shaped our senses in a way that enhanced our chances of survival. But this was achieved by sensory systems that hide the truth about the real world, providing us instead with perceptions that enable the efficient execution of actions that maximize our survival fitness. How?

Hoffman employs a simple metaphor to illustrate this view. A file containing your emails is represented on your computer by, say, a blue rectangular icon located in the center of your desktop interface. Should you therefore assume that your mail is blue, rectangular, and residing in the center of your computer? You know better: computer files have no color, shape, spatial position: they ‘really’ consist of a set of circuits, voltages, software. But would you rather have to learn to toggle voltages to send an email? You are better off making use instead of a simple desktop icon which, while hiding the truth about the computer’s inner workings, enables you to carry out your task efficiently.

That’s it: evolution ’has endowed us with senses that hide the truth and display the simple icons we need to survive long enough to have offspring’ (Ibid., p.8). A seemingly fundamental attribute of the natural world: space, is just ‘your desktop, - a 3D desktop’. And the entities that populate this space: stars, animals, cars, and skyscrapers are just ‘icons in your desktop’. These icons are not to be taken literally; but they must be taken seriously: because our life depends on the actions their appearance in our perceptual field prompt us to take. ‘You don’t need truth - Hoffman says - Perceiving truth would drive our species extinct. You need simple icons that show you how to act and stay alive’. (p.8). Just as the icon on a computer screen helps you save a draft of your email without having to figure out how the computer actually executes the task, the perception (the icon) of a car racing towards you in the street will prompt you to quickly carry out evasive action and stay alive. If instead you were to try and figure out before acting the complex realities beneath that icon, you would assuredly be dead.

This, in a nutshell, is the core tenet of Hoffman’s Interface theory of Perception (ITP).

What makes his theory compelling is that, rather than supporting it only through the language based arguments of the traditional philosophical debate, Hoffman sought to prove it mathematically (aided by Chetan Prakash), within the context of evolutionary game theory (the application of game theory to populations biology initiated in 1973 by John M. Smith and George R. Price; see Jonathan, 2018).

His Fitness-Beats-Truth Theorem, proves that evolution does not promote true perceptions; it actually extinguishes them. Rather, natural selection promotes perceptions which completely hide the truth yet guide useful action. The general conclusion Hoffman draws from this theorem is that ‘Space, time, and physical objects are not objective reality. They are simply the virtual world delivered by our senses to help us play the game of life’ (p.11).

Portrait of Galileo Galilei, 1636

Portrait of Galileo Galilei, 1636

A Long History of Doubting the Senses

Suspicions that our senses do not tell us the truth, the whole truth, and nothing but the truth about the external world run deep in Western (and non Western) thought. Recall, for instance, Plato’s cave allegory (in Book VII of his Republic, ca. 360 BC), according to which our senses only enable us to perceive flickering shadows of true reality; and before him Parmenides (b. 515 BC) had denounced as illusory the seeming changeability of the world. Closer in time, at the onset of the scientific revolution, Galilei had negated, with regard to the ‘corporeal substances’ that make up our everyday world, that any such substance should be ‘white or red, bitter or sweet, noisy or silent, and of sweet or foul odor... I think that tastes, odors, and colors... reside only in consciousness. Hence if the living creature were removed all these qualities would be wiped away and eliminated’ (Galilei 1632; see Goff, 2019, and Quester, 2020).

Note however that for both Plato and Galilei, although our perceptions are subjective constructions, they still portray the objective world in important respects. In Plato’s allegory, a shadow still resembles the object that casts it in some ways; in Galilei’s thinking, any ‘corporeal substance’ possessed objective physical attributes such as its size, shape, location in space and time, whether at motion or at rest, whether it was one or many, which did find truthful representation in our minds. And provided the subject matter for an empirical and mathematical approach to physical phenomena that launched the scientific revolution.

Hoffman’s theory dispenses with all of that. Our perceptual world is conceived of as an interface, wherein space and time, even the Minkowski’s and Einsteinian spacetime, provide the stage in which the icons representing our everyday objects appear. And none of them has an objective correlate in the external world: it is solely related to whatever can enhance our fitness.

In fact, not only is spacetime just a desktop interface, its icons just that: even going conceptually deeper into these constructs still continues to be unrepresentative of objective reality. Even atoms and molecules, genes and neurons, planets and quasars - the stuff of much modern science - all essentially belong to the iconic level of representation.

Does this mean that science is unable to reach beyond the interface, thereby forever limiting us to useful but ultimately fictitious descriptions of reality? (Note incidentally that instrumentalism, the philosophy of science first formulated by Pierre Duhem in 1906 (see Duhem, 1914/1978) advocated the view that scientific theories are no more than useful tools for explaining and predicting phenomena).

Not necessarily. For Hoffman, scientists have a chance of grasping aspects of objective reality by transcending the perceptual interface and by abandoning the whole conceptual framework based upon it. And in his view some empirical and theoretical developments in the physical sciences over the past few decades have been moving precisely in that direction. This includes quantum mechanic’s questioning that physical objects posses definite values of physical properties even when unobserved, and the fact that, as noted by physicist Nima Arkani-Hamer in 2014, ‘Almost all of us believe that spacetime does not exist, that spacetime is doomed, and has to be replaced by more primitive building blocks’. This further implies that the objects within it, as conceptualized by classical physics, must also go. Thus, in Hoffman’s view, key areas of contemporary physics have encountered what he discovered within the precincts of evolutionary theory and perceptual science.

A further consequence of Hoffman’s view that spacetime and all the objects that populate it are constructions of our mind is that they come into existence, and cease to exist, in the blink of an eye. A spoon, Hoffman notes, is an icon that we construct when - and only when - the need for its use arises. The appearance and disappearance of the spoon is not a random event: something in the external world leads to its perception: but whatever else it is, it is not an independently existing spoon. Hoffman’s views accord here with Bishop’s Berkeley (1685-1753) famous dictum: esse est percipi: to be is to be perceived.

On Conscious Realism

According to Hoffman, in essence we are conscious individuals; better still, ‘conscious agents’, continuously given to deciding and acting based upon our iconic perceptions. But: what is, in fine, the ultimate nature of the world that we interact with? What is really out there, if anything? What triggers our senses?

His answer: more and more conscious agents. Conscious agents all the way down. Take the simplest case: a world consisting of just two conscious agents, myself and you, the reader. You are the external world to me and I am the external world to you. We build our world through our interactions. The way one of acts determines the way the other perceives. And we can conceive a universe with an infinity of increasingly complex conscious agents - many arising out of a combination of individual conscious agents - interacting in a bewilderingly complex network of exchange.

Hoffman is committed to eventually arriving at a physical-mathematical theory capable of explaining how interactions between conscious agents can give rise to the spacetime with its objects, an explanation that must include the derivation of the main theories of physics and biology. Good luck, Dr. Hoffman!

Hoffman refers to this view as ‘conscious realism’, but one can regard it as a variety of idealism, insofar as it posits consciousness and its contents as the sole and ultimate reality. And, again, it is not difficult to find precursors of aspects of his ideas in the works of major Western thinkers: from Parmenides and Plato to Berkeley, Kant, Hegel and Leibniz, to name but a few. Nor are aspects of his views entirely foreign to religious systems of thought, including the Abrahamic religions, Buddhism and Hinduism.But what constitutes the true originality of his approach – it bears repeating - is Hoffman’s commitment to formulate it as a mathematically based, empirically testable theory.

Hoffman argues that his theory can help lowering the barriers that prevent a fruitful interaction between science and spirituality. Even God makes an appearance within his broad theoretical horizon: as an infinite conscious agent, its properties to be mathematically defined by a scientific theology.There might even be a doorway to some sort of post-mortem existence, which he does not affirm, but neither denies. Could it be, he wonders, that at death ‘we simply slip out of the spacetime interface of homo sapiens’? (p.181).

Concluding Remarks

It is important to note that ITP, Hoffman's theory of perception, does not require the adoption of conscious realism: they are independent theories even though they can be linked into a consistent theoretical framework. This is good, for I find ITP compelling and rooted in perceptual science, albeit reinterpreted. On the other hand, conscious realism in its current formulation although logically consistent is entirely speculative, only most broadly outlined, and a such undecidable.

Hoffman, it seems to me, is attempting to develop a theory of perception - and of consciousness, more generally - which seeks to transcend mainstream theories still ultimately based upon classical physics. His is a worthwhile move. For the cognitive sciences will eventually have to face the fact that contemporary physical science demands a dramatic reorientation of our way of thinking about the world and the role of consciousness in apprehending it. Perhaps, the long lasting absence of progress in tackling what philosopher of science David Chalmers has dubbed the ‘hard problem’ of consciousness may well be linked to such a state of affairs. A fine topic for another essay.



Duhem, P. (1914/1978). The Aim and Structure of Physical Theory. Princeton University Press.

Hoffman, D. (2019). The Case Against Reality: Why Evolution Hid the Truth From Our Eyes. W. W. Norton & Co.

Goff, P. (2019). Galileo’s Error. Pantheon Books.

Marr, D. (1982/1910). Vision: A Computational Investigation into the Human Representation and Processing of Visual Information. MIT Press.

Newton, Jonathan (2018). Evolutionary Game Theory: A Renaissance. Games, 9 (2): 31.

Quester, J. P. (2015). Do We See the World or Just a Map of it? Retrieved from: https://owlcation.com/humanities/Of-Panthers-Poets-and-the-Marvels-of-Our-Visual-Sense

Quester, J. P. (2020). Materialism Is the Dominant View: Why? Retrieved from: https://owlcation.com/humanities/Is-Materialism-False

© 2021 John Paul Quester