Define Reality

What is reality?  Such a question may initially seem simple, pedantic, and unnecessary.  It’s the world we all live in.  It’s what everyone agrees that it is.  It’s not something to be overly concerned about.  I would disagree.
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Not only do I have history on my side—this is a question philosophers have struggled with since we started calling thinking too much about such things philosophy—but a non-trivial definition of reality has huge implications for other fundamental questions about the world we live in.  Questions about purpose, meaning, and existence: if a fictional story isn’t real, why do we care so much about them?  Further, if our world doesn’t qualify as “real,” should we stop caring about our own stories?  Such questions are the progenitors of deep, existential ruts that are quite easy to sink into.  And beginning to answer them in a reasonable way requires a sturdy, consistent definition of reality. ​Plato and Descartes arrived at this problem through different routes, but found surprisingly similar conclusions: that we have no real foundation by which to trust the world we interact with day-to-day.  Plato dreamed of more: a “realer” world, the shadows of which are the seemingly physical objects we interact with every day.  However, his other world contained the perfect representations of those objects in a way most people simply couldn’t understand.  Descartes, on the other hand, tried to dream of nothing: in his attempt to re-derive his accepted view of the world from the ground up, he found that the only thing he could logically trust was his own existence (otherwise, there would be nothing to do the trusting).  Beyond that, Descartes struggles to show that even his body is real, or that any piece of the world he believes to be around him actually exists.  His struggles are not unfruitful, however; his is the first documented, rigorous search for a trustworthy authority on existence.  Of course, he finds that none exist, for if they did, they couldn’t pretend to be independently trusted (from existence), which is the entire point.  Since two of the most well known thinkers in the human race both question reality on such a fundamental level, it’s not surprising to me to see quite disparate, conflicting views of reality held unquestioningly by many people.

What definition could fit our generally held beliefs about reality, while being legitimately helpful? Let’s try to find something that works.  Obviously, a definition like “reality is everything that’s real” won’t work—it leaves us with the same problems we had before, now ascribed to a slightly different, equally difficult word: “real” versus “reality”.  Alright, then perhaps something a little more specific: “reality is everything that occurs in our universe”.  This definition does guide us much more: we are left with the set of things (I’ll be using “things” throughout this paper, because I don’t know of an equally general word with which to refer to “all types of stuff, whether or not it’s real”) =which have actually happened in one set world.  We can separate these from things which happen in some world we don’t know about, or any fictional world we may encounter.  However, we are still left wanting.  For one, while clearly physical phenomena are obviously included, what about ideas, stories, relationships?  Is math real, or friendship?  Perhaps not, but it seems unfair to “prove” this by simply asserting that they are not.  While such a definition may be consistent, we are left to wonder whether it yields precisely the set of things that truly exist and matter, and no machinery by which to test such a question.  For instance, is an electron real?  We don’t know its position until we measure it—does that make it less real, or only real once it is measured?  More importantly, what about our universe makes it more real than some other one, were we to discover an independent universe or realize that our universe were some kind of Matrix-like simulation?  This definition simply assumes that we have a good working definition of “our universe” and that it must be the basis for reality.  Not only is this assumption seemingly unsupported, such a definition has fundamentally unsatisfying implications.  We can see where our universe is inevitably headed: a vast expanse of nothing, after everything has become black holes and then the black holes have dissolved.  An unavoidable period at the end of every story in reality.  If the universe is reality, we have no power over its conclusion.  Our lives will never result in a meaningful change to reality’s drawn out charge towards its own destruction.  While this conclusion is easy to reach from such a definition, leading one into the nihilistic, existential ruts I mentioned before, it rests on assumptions we have no business making.  We don’t understand our universe.  We don’t understand it’s structure, rules, or role.  We don’t understand reality.  Therefore, although this definition may initially seem just as circular as the former “reality is what’s real” definition, it is actually too strong, relying on assertions we can’t defend, and leading us down potentially mistaken paths to those assumptions’ logical conclusions.

We can learn from the previous definition by identifying its problems.  What, fundamentally, do we not know about the universe?  Well, we still don’t understand exactly how it works—its basic rules and constructors.  It’s possible that an answer to this could fundamentally change our understanding of reality.  For example, one gaping hole in our understanding is the phenomenon of consciousness, which I will tackle in much more depth a future post.  Essentially, while the brain seems to be complex enough to causally explain human behavior (i.e. we understand neither to a similar degree), we have no way to explain (or a priori expect the existence of) human experience—that “there is something it is like to be” human, as Chalmers repeatedly asserts in his paper, “Facing Up to the Problem of Consciousness”.  Chalmers asserts that building a science of consciousness will require adding some new fundamental property to the universe, which is or leads to consciousness.  The fact that we do not understand what seems to be an emergent property of our universe on any level whatsoever—that we would need to define it axiomatically in order to analyze it at all—to me implies that there is still a good possibility of a grand restructuring of our understanding of the of the universe.  If we were to discover some soul-like property of consciousness, our understanding of morality and purpose would have to radically change to account for it.  Hopefully, our definition of reality would not be so arbitrary that it would have to radically shift as well.

To avoid this, we could try to use consciousness to define reality, almost anticipating such a shift.  Many have attempted to use such a definition, something like: “reality is everything observed by consciousness”.  Small word changes could be debated—“observed by” could be replaced with “interacted with” or “experienced by”—but these quibbles ignore the more important implications of such a definition.  Immediately, there are many appealing aspects: it very nearly fits our expected set of real things, it doesn’t create an arbitrary world-hierarchy (any consciousness in any universe would be equally valid, so unanticipated discoveries would not seem to necessitate a change), and it means that reality is entirely shaped by our lives and experiences (instead of the exact opposite implication from the previous definition).  If consciousness disappears, so too does reality.  Such thinking leads us to consider some of the stranger implications of this definition (and any similar formulation).  It implies that if a tree falls in the woods, and nothing notices, its falling isn’t real.  The observable universe is all there is, unless we find some way to see beyond it (which we won’t be able to do without faster-than-light travel).  This seems to make sense in the context of quantum mechanics, in which particles only resolve their position when measured; interpretations of quantum mechanics relying on conscious observation have been proposed.  However, this would imply that the same holds true on every scale, that if everyone stopped noticing X, no matter what X was, it would stop being real.  Object permanence stems from nothing but luck; it isn’t required at all.  Other problematic edge cases pop up rather quickly: what if a consciousness arrived from far away and told us of their reality, which included objects outside our observable universe?  Would our reality expand, since we could theoretically verify the consciousness of the information source, so their observations must be real?  Would their reality simply not be real from our perspective, so that there would be two separate realities?  That doesn’t seem reasonable, as we can interact with each other.  Such problems might also arise between humans with different experiences, depending on the exact wording and interpretation of the definition.  Worst of all, this definition relies entirely on this idea that consciousness defines reality.  Why?  What makes consciousness different in this way?  How can we even define or verify it, even between humans?  We have no idea, despite the potential appeals of such a definition’s implications.  Clearly, this definition, which relies on one fundamental, unreliable, and illogical assumption, answers less questions than it raises.

Something else we don’t understand about our universe is its role within any larger context.  This is what many questions about reality are really asking about—whether there is some meaning or reality to our life which is independent of our day-to-day existence—so assuming that reality is our universe is assuming that we already know that there is nothing beyond our universe.  It forces the question to be something more like, “is there something in our universe that is independent of our universe?”: of course not, because we assumed that the answer was no in our definition.  This seems like a difficult assumption to make without justification, and, indeed, few views of the world actually agree with it.  In fact, Descartes actually appeals to God (the existence of which he manages to prove deductively) to establish the reality of the world around him.  He is able to establish his mind’s existence himself, but for his own body, and anything else around him, he requires God.  We could attempt to use some similar definition: “reality is everything God creates” or “reality is everything in the multiverse” or “reality is everything happening in the universe simulating ours, however many levels up”, but each of these will be problematic for two fundamental reasons.  Firstly, they shift all of the difficult problems of defining reality to defining some other thing: what makes God real, or some other universe?  We don’t know, for the same reasons that we can’t answer that question for our own universe.  Secondly, on what grounds can we be so sure of what exists beyond our own universe?  God requires faith, multiverses arise only in some interpretations of physics, and the simulation argument rests on logic I disagree with and futuristic predictions we know we can’t make, since we struggle to so much when dealing with the Fermi paradox.  These are not helpful or good definitions of reality.
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With all this in mind, I would like to provide my own definition of reality, developed with the help of a friend:

The reality of X is the degree to which X affects everything else.

This definition, like the definitions before it, is immediately appealing for many reasons: it agrees with our commonsense notions of reality, it makes very few (if any) arbitrary distinctions or assumptions, it can agree with many interpretations of quantum mechanics, and it leaves our understanding of reality open for significant changes in the future.  Additionally, this definition allows, quite clearly, for ideas, fictional characters, relationships, and other abstract ideas to be real, although typically not as real as other people or objects in “our world”, resolving many of the problems with prior definitions.

​Firstly, I want to explain how this definition agrees with quantum mechanics, and physics in general.  The reality of an electron (or any object we may not know anything about) is defined by its interactions with other things.  If it could have been somewhere it wasn’t and influenced everything around it the same, then its position isn’t real.  If someone asserts that it is in a whole range of places at once, that’s fine; it shouldn’t have a “true” position if that “true” position wouldn’t affect anything differently.  This means that object permanence doesn’t hold only in the cases that it shouldn’t.  If the evidence for something were destroyed so soundly that no effects of its ever existing were present anywhere at all, it wouldn’t be considered real.  Essentially, reality is only what we can confirm is real, since it has an effect.  We may never be able to work out exactly what happened on Earth 4 billion years ago, but we know it existed, because its existence back then affected everything around it, from the apparent age of the rocks we find, to the orbits of the other planets.  However, if there are 100 equally plausible accounts for exactly what happened, with no way to currently discern between them even by analyzing the data held in every atom we can find, then we must consider each of them equally real—what grounds would we have to believe otherwise?  One could assert that only one of them happened, but again, we have no way to determine which it was, so in our current reality, each of them could have happened.  In this way reality is only as real as it needs to be, nothing more, no matter how strange the physics gets.

Secondly, I want to demonstrate the power of considering different degrees of reality by exploring the malleability of this definition in the future.  Let’s first say that our universe is all there is—no God, no multiverses, it’s not a simulation, nothing of that sort.  There is nothing else to find.  Then “everything else” would refer to our universe, and our definition would work just fine.  However, say we do find one of those things to be true.  Then “everything else” would refer to a much larger set of things, and everything we previously knew of would have to be reevaluated for how much it interacted with this larger set.  Our previous “reality” would presumably be less real than it had been before, but it wouldn’t stop being real.  It would simply be part of something larger than we knew about before, as we might expect.  Even if we are in a simulation, and someone only considers the “original” universe to be reality, our universe must be fully represented within that one, so everything which affects anything in our universe would still have some degree of reality, just in a more indirect way.

Such a definition works very well with stories and other abstractions as well.  Say someone tells me a story and it makes me see the world differently, or at least able to tell that story to someone else in the future.  Clearly, that story has affected me, and so its plot, characters, and ideas have some degree of reality, although they probably affect many fewer things than I do as a human.  Say this story was shared all over the world, however, and affected millions, or billions, of people.  Then it will have become very real.  In order to explain many of the conversations, beliefs, and actions of many people, one would have to look to the story itself, how the characters interact in the story, what is resolved between them, and so on.  The story will have become very, very real.  Similarly, math is real under this definition: we have come to see that the implications of calculus, probability, and number theory were affecting us before we even conceived of them as topics, and, after their discovery, these properties have become even more real from our teaching them to billions of other humans.  Stories, math, relationships, and other abstractions are real to the degree that they affect everything else.  Stories never thought of have had little to no effect on the world around us, and so they are less real that those which have affected many peoples lives in very deep ways.  Under this definition, abstractions do have a place within reality.

Finally, consciousness actually plays a very important role in establishing reality, even though it isn’t explicitly mentioned in our definition.  In our experience, consciousness is always associated with a powerful, feedback-filled, malleable system.  If anything were to affect such a system, by the consciousness’s observing it or because of its implications for the system (like the effect of the square-cube law on the structure of the brain), then it would be incredibly real, because consciousnesses affect both themselves and the world around them in incredibly complex ways.  Most humans, for example, will interact with hundreds or thousands of other humans in their lifetime, and an action caused by their brain could easily affect millions of others to some degree, through a news story, a sign on the road, or even the lack thereof.  Thus, humans, and almost everything conscious, are powerful constructors of reality, due to the immensely complex interrelations necessarily present in and caused by such systems.  This definition of reality makes very few assumptions, fits our prior ideas about what qualifies as reality very well, will fit almost any future interpretation of the world around us, and yet still works powerfully to differentiate between the reality of different things.

This definition has many non-trivial implications for day-to-day life.  In other words, it is actually useful, despite its seeming like a tautology.  I’d like to demonstrate one implication in particular: whether or not a given thing “matters”.  This is immediately linked to one’s notion of reality.  If X isn’t real (or is less real than Y), then you probably think you should care about X less than Y (whether you actually do can be quite difficult to change).  Having a usable definition of reality allows us to potentially distinguish between X and Y more objectively.  For instance, if you do something that affects almost no one else—a small misstep while thinking to yourself that you quickly correct or accidentally dropping a ball while learning to juggle—it is much less real, and thus much less important, than more public actions: what job you choose and how well you work, what friendships you make and how well you keep them, or a book you publish and how well it was written.  In fact, the only discernible effects of those less real examples will most likely be the ways in which they affect your brain as you learn from them, leading you to avoiding such a thought or catching the balls more in the future.  This difference points to which things one should be concerned about; if something seems inconsequential, it might very well be.  However, if something is a symptom of some kind of larger problem, like a white lie implying an inclination to dishonesty (and the normalization of such actions), it will probably affect many parts of your and others’ lives, and thus is a very real problem—one to address.  If everything were equally real, we couldn’t draw such distinctions; all problems would be equally important.  If reality were merely physical, math “problems” seem to matter much less.  However, by this definition, if an idea has a large effect on you or large implications for others, it is a very real problem, no matter how it is manifested.

Reality may seem like a topic we do not have the tools to address, or a trivial thing to debate.  I hope that this analysis has demonstrated to some degree the ability we have to begin addressing such a topic, and the importance of its conclusions.  We are not machines marching blindly through our work.  We care about the larger story in which we participate, and knowing how we can best participate in a world that hands us either no hint of an objective or myriad unclear and seemingly contradictory ones.  Deciding exactly what we believe is reality helps us begin to analyze this problem more quantitatively, giving us the tools to sort through many different approaches to a necessarily intricate and difficult life; such complexity is required for reality.