I concluded the last installment in this series with a deceptively simple claim: Things exist. This two-word quip is a scientific hypothesis, an explanation for some of my subjective experiences, specifically, my ability to see and touch and hear and small and taste, well, things. The explanation is that these things that I perceive really do exist in point of actual physical (and possibly metaphysical) fact, i.e. that there is an objective reality that actually exists "out there", independent of my mind. This is so obviously true, so obviously the correct explanation that there seems at first glance to be no point in discussing it at all. But as we will see, this hypothesis actually turns out to have some pretty serious problems, and in fact, when we drill down far enough, it will actually turn out to be wrong.
But let's take this one step at a time.
First, let's give this hypothesis a name. I'm going to call it the Objective Reality hypothesis, or ORH for short. This hypothesis says that some (though not necessarily all) of my subjective perceptions can be accounted for in a totally straightforward way by the existence of actual physical things. I can see and touch and hear other people because there actually are other people, and we can all agree that there are chairs and tables and computers because there actually are chairs and tables and computers.
At this point you may be thinking, well duh, of course the reason everyone agrees there are chairs is because there really are chairs. But it's not so simple. Consider, for example, rainbows. People will agree that they see a rainbow just like they agree that they see a chair, but a rainbow is unlike a chair in some fundamental ways. You can see a rainbow, but you can't touch it. If you try to get close enough to a rainbow to touch it, the rainbow will disappear. Rainbows are part of objective reality but they are not physical things. Rainbows are just water droplets lit up in a very particular way.
Rainbows are not the only things that look like they might be physical objects but actually aren't. You are probably reading this on a computer screen, which can mimic the visual appearance of just about anything. Before computer screens there were movies, and before movies there were paintings, and after computer screens there will probably be virtual reality glasses or implants. As technology improves, it gets harder and harder to distinguish actual physical reality from a simulation.
Aside: a while ago I got a demo of the Apple Vision Pro, which is a virtual reality headset. While you are wearing it what you are actually looking at is a pair of tiny screens. But there is also a camera which projects an image of whatever the headset is pointed at onto the screens. The illusion is so compelling that during the demo I actually forgot that I was looking at a screen and became convinced that the screens were transparent, that I was actually looking through them and directly seeing the room I was in.
Which brings up an interesting question: how can you be sure that the things you perceive as actual physical objects are in fact actual physical objects and not a simulation? How can you tell the difference between "real" objective reality and a high-quality virtual reality, one that includes all of your sensory modalities? How can you be sure that reality is actually real and you are not just living in The Matrix?
I'll leave that as an exercise for now and proceed on the assumption that objective reality is actually real, and that part of this objective reality consists of real physical objects like chairs. I'm going to refer to such objects as Things with a capital T. Objective reality includes abstract things like words and ideas and sounds, and ephemeral things like rainbows and the images on computer screens. These are lower-case-t things, but they are not upper-case-T Things. When I refer to upper-case-T Things I mean actual physical objects made of matter.
One of the distinguishing characteristics of Things is that they exhibit certain regularities in their behavior. The most important of these is something I call the Law of Location: Things exist in particular places at particular times, and they move between different locations along continuous trajectories. This is the thing (lower-case t) that allows us to ascribe identity to Things. We can distinguish (say) this chair over here from that chair over there by virtue of the fact that this chair over here is, well, over here, and that chair over there is over there and not over here. We can move the chairs so that the chair that used to be over here is now over there, but because the chair had to move in a continuous trajectory we can still meaningfully say that the chair that is now over there (after we moved it) is the same chair as it was before we moved it.
The Law of Location is so deeply ingrained into our psyches that even giving it a name seems like I'm belaboring the obvious, but there is a good reason for it: there are Things — or at least things that appear to be Things — that do not obey the Law of Location. But again, let's not get ahead of ourselves.
Instead, let's talk more about chairs. For some reason, chairs are a favorite example among philosophers and religious apologists. There is a thing in philosophy called the "problem of universals" which asks the question (and I'm just quoting Wikipedia here): "Should the properties an object has in common with other objects, such as color and shape, be considered to exist beyond those objects? And if a property exists separately from objects, what is the nature of that existence?" In other words, is there such a thing as "chairness", some kind of ineffable chair-like essence which all chairs have in common? (It sounds a little less silly if you put it in terms of other kinds of properties: is there such a thing as "redness" which all red things have in common? Is there such a thing as "loudness" which all loud things have in common?)
But this is not about philosophy, this is about science. Science starts not with abstract philosophical questions but rather with observations, and one of the observations we can make is that chairs are a thing, that is, people talk about chairs and they seem to be able to say coherent things about them. But what actually is a chair? When people talk about chairs, what are they actually talking about?
At first glance this seems like a silly question. Everyone just knows what a chair is. It's something like this:
But trying to get a handle on exactly what is meant by "something like this" turns out to be not so easy. What exactly qualifies as "something like this"? For example, is this a chair?
It is very unlike any of the chairs in the previous picture. It doesn't have a back. You can sit on it, but it's a weird kind of sitting where some of your weight is supported by your knees and there is no support for your back. And what about this?
That is a photograph of a sculpture in Geneva, Switzerland called "Broken Chair". It looks like a chair. In fact it looks more like the chairs in the first photo than the one in the second photo does. It has four legs (notwithstanding that one of them is broken) and a back support. But you can't really sit on it because it is the size of a multi-story building. So is it a chair?
And what about this:
This is a (picture of a) Thing that was once a chair, but is it still a chair? You might actually be able to sit on it, but it only has two legs. Does a pile of bricks holding up the other side count? If this is a chair, are the bricks part of the chair? They are kind of essential to the chair's function, but I think most people would say that they are not part of the chair, that they are merely holding up the chair — if indeed a chair broken to this extent still counts as a chair.
And what about this:
That has four legs and a back and it's the right size, but if you tried to sit on it you would be in for a nasty surprise.
Here is one final example. This is pretty clearly a chair:
Specifically, it is a folding chair. It is designed to be folded up so that it occupies less space for storage, like so:
When a folding chair is in its folded-for-storage configuration, you can't sit on it any more. So is it still a chair? Most people would say yes, of course, because all you have to do to be able to sit on it is unfold it. But the same can be said of broken chairs: all you have to do to a broken chair to be able to sit on it is repair it. Is there a substantive difference between unfolding a chair and repairing a chair beyond the mere quantity of effort involved? At what point does the effort required to repair a chair render a chair so broken that it is no longer a chair?
It gets worse. Suppose we take a broken chair and repair it. Is it still the same chair as it was before, or is it a different chair? This question is called the "Ship of Theseus" problem because it was originally posed as a thought experiment about ships rather than chairs, but the puzzle is the same: take any Thing — a ship or a chair or whatever — and start replacing parts of it until at the end there is nothing left of the original. Is the result the same Thing or a different Thing?
We can make this conundrum even more explicit: Take any Thing that can be disassembled into parts, and a bin of replacement parts. We can take parts out of the bin and make a new Thing, a copy of the original, but this new Thing is clearly a different Thing because the original still exists. Now disassemble the new Thing and use the parts to replace parts of the original one by one. The end of that process is the exact same set of parts that comprised the new Thing that we made before, so this must also be a new Thing. Indeed, it is the same new Thing as before. But there is obviously no clear dividing line between when the old Thing became the new Thing.
This lack of sharp dividing lines is fundamental to the nature of Things. It will become very relevant later when we start talking about the nature of humans and brains and minds and whether or not abortion is murder, but we are getting WAY ahead of ourselves. For now let's get back to the fundamentals: chairs, and how they relate to the scientific method. I want to be very explicit about what is going on at this stage in the discussion in those terms. I am trying to explain some of my subjective experiences. Specifically, I am trying to explain my gut feeling that the word "chairs" has a meaningful referent in objective reality, i.e. that there really are chairs "out there" in the real world. The hypothesis under consideration is that chairs are Things, and what distinguishes chairs from non-chairs is some property — chairness — that chairs possess and non-chairs do not. The hypothesis is that this property is, like the chair itself, part of objective reality, that it's a real thing (though obviously not a real Thing) "out there" in the world. This position is called essentialism.
Essentialism is problematic for two reasons. First, it turns out to be really hard to get a handle on exactly what Things are chairs (and thus possess this hypothetical "chairness" property), and second, we can change whether or not a Thing is a chair simply by moving parts of it around. In fact, we don't even need to move parts of it around. Imagine carving a chair out of a single (huge) block of wood. The end result is a chair, and so would have "chairness". But notice that the only things that moved during the carving process were the parts of the block of wood that were not part of the final chair. The wood that makes up the chair doesn't move at all. So where did its final "chairness" come from? Was it there in the block of wood all along, or was it somehow imbued into the remaining wood during the carving process?
To help answer these questions let us consider a different property: redness, a hypothetical property shared by red things. We can see that redness is different from chairness merely from the structure of the word. The word "redness" is built out of an adjective — red — whereas "chairness" is built out of a noun, which is what makes it sound kind of funny. There is no noun associated with redness, we have to resort to the phrase "red things", which immediately suggests another interesting puzzle: are there any red things that are not red Things? Does a thing have to be a Thing in order to be red? Is Santa Claus's coat a Thing? When a pixel on your computer screen turns red, is it now a red thing? Is it a red Thing? The red band in a rainbow pretty clearly has redness, but is it is not a red Thing (because a rainbow is not a Thing). But is it a red thing?
There is another difference between redness and chairness: chairness (if it actually exists) can be detected using multiple sensory modalities. Chairs can be seen and touched, so even a blind person can (at least potentially) tell whether something is a chair. But redness can only be seen -- it cannot be touched or heard or smelled or tasted. So can a blind person tell if something has redness? (Yes, they can! Figuring out how is also left as an exercise, but here is a hint: even normally sighted people cannot see ultraviolet light. So can normally sighted people tell if something has ultra-violetness?)
But all of this is a distraction. My subjective perception is that chairs exist and red things exist and other humans exist and (and this is the important part) the vast majority of other humans agree on whether a thing is a chair or whether a thing is red in a huge number of cases. How do we explain that overwhelming agreement if chairs and red-things — and hence chair-ness and redness — are not real?
Up until about 100 years ago that was still a question open to legitimate philosophical debate, but no more. The answer is as prosaic (to a modern ear) as it is profound: In the words of Richard Feynman, matter is made of atoms, little particles that move around in perpetual motion, attracting each other when they are a little distance apart, but repelling upon being squeezed into one another. All Things are made of atoms. But unlike chairs, there are bright lines separating different kinds of atoms. There are exactly 92 different kinds of atoms that occur in nature, plus a few dozen more than we can produce artificially. Then there are a few variations on those basic types called "isotopes" and "ions", but that's it. Every Thing that you see is made up of some repertoire of those 92 different kinds of atoms. What we call "chairs" and "tables" and "red things" are nothing more than different arrangements of these 92 different kinds of atoms.
I don't expect you to take my word for this. I don't even expect you to take Richard Feynman's word for it. At this point I am advancing this idea in the same spirit as it was advanced in the 19th century when the idea was still controversial: as a hypothesis. My burden is to convince you that this hypothesis is better than the essentialist hypothesis, that it is a better explanation for what you observe. And I have to do this without simply saying, "That's what science says" because that would just be begging the question.
That is what I intend to do in the next installment. But in the meantime I am going to make a prediction: I don't actually have to convince you that matter is made of atoms. I'm pretty sure you already believe it. In fact, I'm pretty sure that your belief is so strong that the mere suggestion that this is a hypothesis that is open to question strikes you as absurd. Of course matter is made of atoms! Everyone knows that!
If you don't already believe this, if you are an anti-atomist living in the 21st century, please let me know in the comments. I would really like to learn how you came to question this.
No comments:
Post a Comment