Some things can be predicted with extraordinary accuracy, provided one knows the right facts beforehand.
For instance, if you have a flat table with one end raised up a bit, so you have an incline, and you release a ball at the top part of the table, you can calculate precisely how long it will take to roll off the table. You will also be able to predict its exact speed when it leaves the table. Further, you’ll be able to calculate the precise point it hits the floor and what speed it will have the moment it makes contact.
You can do all these things provided you have the relevant information beforehand: the length of the table, the angle it’s inclined, the height of the table off the floor, etc. You also need to know the operative laws of nature, the equations in physics. None of this information is that hard to get; students of elementary physics make these calculations all the time.
Now consider a much more difficult case: a leaf blowing down the street on a windy day. This can’t be predicted: no matter how hard we try, we can’t say where the leaf will end up in even one minute. But this failure on our part is not because the leaf-street case is physically different from the ball-table case. The only reason we can make predictions in table case but not the leaf case is that there are many more factors in the leaf case—too many for us to know about beforehand. We have no idea what the wind speed will be, how long it will last, or what direction it will come from. We don’t know how sticky the pavement is. There are just way too many variables. But that is the only difference separating the leaf case from the ball-table case: the latter has far fewer unknown variables.
The operative point: if we had knowledge of all the relevant variables in the leaf case, then we could predict the various details of the path of the leaf just as well as we did for the path of the ball. The principles—the laws of nature—are exactly the same in the two cases.
The same holds for a living organism such as a flower. If we knew all the relevant local factors about moisture, soil composition, sunlight, wind, the insides of the flower, temperature, and the rest—including the relevant laws of nature—then we would be able to predict the exact details of how a flower grows over time. The fact that the flower is a living thing while the ball rolling on the table was not is totally irrelevant: if one knows the relevant “initial conditions” (the data) and laws of nature, then one can predict all the details about what the object in question will do next. That’s because the flower, soil, moisture, air, and sunlight are made of physical stuff that obey the laws of physics—just like the ball-table and (dead) leaf-street cases. The laws of physics simply don’t care whether the object in question is living or not.
Let’s define determinism as the idea that what’s true of the ball, leaf, and flower is true for our bodies too: given the initial data plus the laws of nature such as ‘E = mc2’, what happens in our bodies is fixed. Be careful: we aren’t defining it so that it applies to bizarre entities in black holes or wherever. We care about human free will, so we might as well make the restriction to humans explicit. If determinism is true for humans but not black holes, we probably won’t care too much about the exception for black holes.
We need to fully understand determinism before we can intelligently ask whether it’s true. Fortunately, there’s an excellent way to keep the import of determinism firmly in mind:
Imagine an alien who comes to visit earth. Suppose she is practically omniscient compared to us. Suppose further that when she looks at us, with her alien sense organs, she sees us as a mass of atomic particles, kind of like a swarm of bees that are tightly related to one another. In fact, that’s how she senses all the objects on earth, including the earth itself: nothing more than swarms of atomic particles that move around together. She uses her vast intelligence, miraculous sense organs, and advanced technology to scan all the atomic particles in our entire planet plus everything on it. Further, suppose she knows all the laws of nature that apply to objects on earth.
As far as she’s concerned, we are no different from the flower, leaf, or ball. The only differences are that we are made of more particles and there are more calculations to make in predicting what any one of us will do next. But that’s not an interesting difference. It’s like the difference between calculating ’55 x 16’ and ‘5345335345345435 x 859435883753’: one is a lot harder than the other, but it’s just the same type of calculation in each case.
When I say that the calculation for a human is no different from that for a flower, leaf, or ball, I am not saying that there are no important differences among the four objects. That would be ridiculous. Think of it this way:
Suppose we get a doll that’s the same size, shape, and weight of a human. (So this is not one of those blow-up sex dolls.) Our doll is made of plastic, wood, and other materials and is the exact same size, shape and weight as your body. Furthermore, we can remotely control the doll to move its arms, legs, fingers, mouth, etc. Now we take the doll and you and throw the two of you off a tall building (sorry about that). We also control the doll so that she does all the same movements as you: the same panicky flailing of arms and legs, the same shouting, etc. Here’s the relevant point: the two of you are going to hit the ground at exactly the same time. The fact that you’re living and conscious while she isn’t makes no difference at all. All that matters, in calculating how long it takes the two of you to hit the ground, are factors like mass, shape, wind currents, movements while falling, etc. It doesn’t matter one bit that you’re terrified and she’s not even living, let alone conscious and terrified. The very real differences between you and the doll—life, consciousness, terror—simply don’t matter when calculating what your body does next.
The idea behind determinism is that what I just said about calculating the time when you hit the ground also apply to calculating what you’re going to do next while reading this chapter. Maybe you’re going to pick your nose. The super intelligent alien will be able to know that you’re going to do that—she’ll figure it out just by doing her massively complicated physics calculations. Your body is a physical system that obeys physical laws of nature—just like the ball, leaf, and flower. Even if you have a disembodied soul, your body is an entirely physical system subject to the laws of nature like every other physical system.
Notice that the alien isn’t making her predications of what your body does based on data such as ‘This person really likes to pick her nose when reading philosophy; she hasn’t picked her nose yet; so, she’ll probably pick it soon since she’s been reading philosophy for a while now’. And if she predicts that you’re going to drink a beer, her data won’t include anything like ‘This guy’s parents were both alcoholics; so, he’s going to be one too’. Nope. Her calculations are purely mathematical, using equations from physics. Remember, when she sees you she sees a huge swarm of atomic particles that obey certain equations. She doesn’t care about the last time you picked your nose or whether your parents were alcoholics; facts like that don’t enter into her calculations. When she makes a prediction of what your body does next, all she’s doing is this: scanning you and your entire environment down to every last particle, collecting all the data on all those particles (their mass, electric charge, velocity, etc.), plugging all that data into the complicated equations that express the laws of nature, and then calculating the result. The “result” will be something of the form ‘These particles will be at such-and-such location in 24 seconds and will have such-and-such velocities’. All the ‘such-and-such’s will add up to your picking your nose in 24 seconds.
But 24 seconds is nothing. If we had enough data, we could calculate what things will do for a lot longer time period than that. To return to our modest ball-table example, if we have all the relevant data about the room in which the ball is rolling on the table, then we will be able to calculate everything it does after hitting the floor: the number of bounces on the floor, the precise arc of each bounce, the direction the ball rolls, the directions it goes once it hits some things on the floor such as a trash can, and the location of where the ball stops rolling. Similarly, if the super alien scans every atomic particle in the entire solar system, then she will be able to know about every possible influence on your body and will be able to calculate your entire life. For instance, she will know the precise moment your heart stops beating when you die. Again, no human could figure any of this out, and the amount of complexity is staggering, but like I said earlier it’s really just the difference between solving simple and complicated problems in arithmetic.
She can calculate what your mouth will be doing. So, she knows that you will say ‘Could you close the door?’ exactly 14,453 minutes from the moment you read this sentence. But will she know your thoughts or desires? Well, she will know everything about your brain. And she will know every sound you make while talking. She will know every word you type. She knows all the physical facts about your entire life before they even happen. That’s what determinism says.
I haven’t said that determinism is true. I’m just in the process of telling you what it says.
If determinism is true, then the physical facts about the past and the laws of nature determine or fix the future. That’s the key to determinism!
When we think about determinism we are inevitably drawn to thinking about free will. So, what does it mean to say that you have free will; that you can choose to do X or Y; that what you do is at least occasionally up to you?
Ordinarily we say that while you are standing in a grocery store deliberating about whether to buy Pepsi or Coke you can choose either one. You can choose Pepsi and you can choose Coke; you can do either one. Suppose that in fact you chose Coke on a particular occasion. Even if you chose Coke that time around, we ordinarily say that you could have chosen Pepsi—that’s your freedom.
Free Will: Often we are in a situation in which we can do A and we can refrain from doing A—both choices are in our power. We are able to do A and we are able to refrain from doing A. Whichever choice we happen to make (do A, don’t do A), it remains true that we could have chosen differently.
The key idea behind free will is that even if you didn’t do A, you could have done A. If you program a robot to walk into a grocery store, put its metallic arm around the Coke bottle, pick it up, walk to the checkout, pay for the bottle, and walk out, well, you’ve done an impressive amount of programming. But the robot could not have chosen the Pepsi bottle. It was determined to pick the Coke, as that’s how it was programmed. Having free will means being unlike the robot in the fact that one is able to do otherwise than one actually did. That’s what I mean by ‘could have chosen otherwise’ or ‘could have done differently’.
We face several questions at this point, which I’ll address in order:
1. Is determinism true?
2. What is free will really?
3. Does determinism conflict with our having free will?
In order to understand the reasons why many experts think determinism is true, one needs to understand what ‘physical’ comes to, since determinism applies only to what is physical. When philosophers use the term ‘physical’, they mean to include, as physical, trees, ice cream cones, planets, brains, earthquakes, supernova, electrons, photons (which are invisible), atoms, air, water, forces (like gravity), electromagnetic waves, magnetic fields, kinetic energy, etc. Anything that boils down to the behavior of atoms and their constituents counts as physical. Our bodies are of course entirely physical: we are made of atoms. And the processes going on in our bodies are all physical as well: the digestion of your lunch, your eye movements, your muscle twitches, the electrochemical processes involving neurons in your brain, the blood flowing through your veins, etc. Anything studied in physics, chemistry, and biology is, by definition, “physical”. To say that something is not physical is to say it lies outside the realm of the physical. It means that the thing in question, the “non-physical” thing, doesn’t boil down to atoms or processes involving atoms at all: so it lies completely outside the molecules, atoms, forces, fields, and waves studied in physics, chemistry, and biology.
So, to say that something is “physical” is not to deny that it’s mental. A physical thing may or may not be mental as well. On the face of it, you are both physical and mental, and you are a single thing.
Science assumes that what happens in the physical world is fixed by prior conditions via the laws of nature. When faced with a new and unexplained physical phenomena, scientists assume that that phenomena was caused to happen by prior conditions according to laws of nature; so, they go looking for those conditions and laws in order to find out how the phenomenon came about. And you know what?
This works. In virtually every case, we eventually find out what the prior conditions and laws are that brought about the previously unexplained physical phenomenon. Sometimes the discovery process takes a day while other times it takes centuries, as it all depends on the difficulty of the case. But the assumption mentioned in the previous paragraph holds up fantastically well. Since science is so successful, and its success depends on the assumption that physical phenomena are determined by prior conditions plus laws of nature, that’s excellent evidence that determinism is true. The evidence is not conclusive, but it’s very good.
The only reason so many of us are inclined to think human action is different is that we do not yet know of the exact causes of our behaviors (although we know that the causes are in the central nervous system). Let’s address some common objections to determinism:
Objection 1: doesn’t contemporary physics say that determinism is false? Doesn’t it say that some things that happen inside atoms have no causes at all?
Response: we don’t know yet. The jury is still out on that matter. (Occasionally, popularizations of physics say otherwise; ignore them.) But we’re really interested in human actions, not quantum events, so it’s not clear that it even matters.
Objection 2: we know only a tiny bit about this enormous universe. So how can we say with any confidence that every physical phenomenon is determined by prior conditions plus laws of nature?
Response: once again, see science’s success. Also, as we noted earlier we don’t care about bizarre events in black holes (say), all we care about are ordinary human actions. We care about whether they are determined. Even if there are remote things in our enormous universe that are undetermined that won’t matter to free will.
Objection 3: if our minds aren’t physical, if we have honest to goodness immaterial souls—so our minds are somehow connected to but distinct from our brains—then our decisions are not part of the physical world, as they are the province of our minds. Determinism is true only for physical events, not mental events. So there is no conflict between determinism and free will because determinism is true only for the physical world while free will has to do with our minds.
Response: First, the idea that we have immaterial souls is very controversial. In fact, the clear majority of people who actually study the mind—cognitive scientists and philosophers of mind—reject that idea (see chapter 5). But set that aside and assume that the whole “non-physical souls” idea is totally true. Even so, if determinism for physical events is true, which the objector has granted, then we still have something very counterintuitive: all we say or do or write is still determined! Maybe your internal mental decision to say ‘yes’ to a marriage proposal takes place in your non-physical, immortal soul, but the actual utterance of your saying ‘yes’ is a physical event that the super alien knew, before you were even born, was going to happen at such-and-such a time on such-and-such a date. Everything you actually say or do is a physical event of your body, and it’s all determined beforehand, provided determinism is true.
We have seen that there is good if not rock-solid reason to think that determinism, restricted to humans anyway, is true. It’s also pretty intuitive that we have free will. But as anyone with a functioning brain can see, there is at least a prima facie tension between the two. So do free will and determinism really conflict in such a way that if determinism is true then we don’t have free will?
Recall our earlier example of the exercise of free will: at the grocery store I chose the Coke instead of Pepsi. If determinism is true, then before I was even born it was already determined that I would choose the Coke. But if that’s true, then it seems like I could not have chosen the Pepsi, since it was already fixed that I would not do so. In sum:
My Free Choice: I could have chosen Pepsi.
My Determined Action: I couldn’t have chosen Pepsi.
It really looks like the conflict is about as stark as it could get. We can’t possibly have free will if determinism is false, as it’s plain that they conflict.
Nonetheless, many philosophers disagree with that conclusion. The compatibilist says that both free will and determinism can be true. The conflict is merely apparent, not real. Compatibilism comes in many varieties, mainly because there are many ways of construing ‘free will’. We’ll look at just two.
Here’s what one kind of compatibilist says:
Compatibilist 1: Look, even if determinism holds, it’s still true that I decided to get Coke and as a result of that very decision I reached for the Coke. My decision caused my action. And even if determinism holds it’s also still true that if I had decided on Pepsi, then I would have reached for Pepsi. What more could you want? That’s all freedom amounts to and it’s compatible with determinism. Having free will means just this: you decide to do something, and then as a result of that decision you do that thing. In the Coke case that’s exactly what happened even if determinism is true! So, we have free will and it doesn’t matter if determinism is true.
In response to this compatibilist, it is usually granted that your decision (you decided to reach for Coke) was the key causal factor in your action (your action of reaching for the Coke). So, sure: you decision caused your action. But the problem with this defense of compatibilism is that your action was programmed in you a billion years ago! It was already fixed, before you were even born that you would reach out your arm to grasp the Coke bottle. You’re like a toy that’s been programmed to say ‘I would like some Coke’ and then reach its metal arm around a Coke bottle. Maybe some computers can think, but surely this toy hardly had any freedom. We still need to address the simple argument given earlier:
My Free Choice: I could have chosen Pepsi.
My Determined Action: I couldn’t have chosen Pepsi.
Compatibilist 2 is better than compatibilist 1 because she confronts the apparent contradiction head-on. In effect, she says that ‘could’, in the two indented sentences above, has different meanings that make the two sentences compatible: they can both be true.
Before we get to her theory, let’s look at a much simpler case of her general idea. Suppose we are at my house preparing to go to a park to play baseball. I gather up a few balls and baseball gloves. You ask me if I have any baseball bats. I reply with ‘There are some bats in the attic’ and go up there to get them. A few minutes later a friend of mine asks whether I got rid of the bats that decided to take up home in my attic. I reply with ‘There are no bats in the attic’. Clearly, I have not contradicted myself, despite the linguistic appearances: my uses of ‘bats’ have different meanings: at first I was talking about baseball equipment and later on I was talking about certain flying mammals. Our second compatibilist is saying that a much more subtle shift in meaning is occurring in our two sentences ‘I could have chosen Pepsi’ and ‘I couldn’t have chosen Pepsi’.
When we say that I could not have chosen Pepsi, because of determinism, what we mean is something more or less like this:
(a) Given what had already happened in the past, the laws of nature forced me to not choose Pepsi.
But when we say that I could have chosen Pepsi, because of free will, we are using ‘could’ in a different way. We are saying something roughly along the following lines:
(b) No one was forcing me (at gunpoint say) to avoid the Pepsi.
(c) I didn’t have some weird psychological compulsion that makes me avoid Pepsi at all costs.
(d) It was logically possible that I choose the Pepsi; that is, if we ignore or temporarily set aside facts about the prior causal history of the universe then the possibility of my choosing the Pepsi is real.
Thus, compatibilist 2 is saying that even though the determinism and free will statements look incompatible, they aren’t because (a) is not incompatible with (b)-(d). Hence, we can have free will even if determinism is true.
I can’t go over even a fraction of the considerations relevant to figuring out if she’s right. Instead, I propose to say a few words about the consequences of her, or some other compatibilist, being right. In order to do so, let’s first consider a simpler case.
If someone asks of a particular actress, ‘Is she a great actress?’, the right answer usually is ‘Well, it depends what you mean’. That’s because there are several notions of a “great actress” and a particular woman might fit some but not all of them. For instance, it might be said that a “great actress” is one whose work has made a great deal of money, as that indicates that the audience loves her work. Alternatively, it might mean that she has won a bunch of awards, such as an Oscar for acting. A third notion would be that her acting is held in very high esteem by experts on acting, such as the teachers of actors. If someone asks whether Meryl Streep is a great actress, we immediately answer affirmatively because she will meet any notion of acting greatness you like. But for other actresses, we might say that she fits some notions but not others.
This isn’t true of a term such as ‘irrational number’. There aren’t multiple notions in that case. You can’t say ‘Well, the number in question is irrational under some but not all notions of being an irrational number’—whereas you can say ‘Well, the actress in question is great under some but not all notions of being a great actress’. But what goes for ‘great actress’ is true for ‘free will’: there are several notions of free will. In fact, we have already seen two of them. Compatibilist 1 said that having free will just means that one’s decisions cause one’s actions. Compatibilist 2 says something a bit more sophisticated if not terribly specific: having free will means something along the lines of (b)-(d), suitably generalized. And if one goes to the professional literature on free will, one can discover many more notions of free will, a good number of which are plausibly compatible with determinism and even central to what it means to be a person, or at least a human person.
By my lights, the main question to ask at this point is the following:
Even if there are 374 notions of free will that are completely compatible with determinism, and even if some or all of them are very important to our lives and perhaps even go a long way in explaining why humans are such distinctive animals, is the deeply disturbing feature of determinism lessened by the truth of compatibilism?
Maybe it’s just me, but I would answer negatively. Even if the philosophers convince me that I have “free will” in any of several important and interesting senses, if determinism is true as well then those notions of free will are cheapened in some horrible way. You can talk all damn day about how special humans are in having such-and-such kinds of morally important free will, creativity, and other lofty characteristics, but if it was determined before I was even born that I would get married exactly 45,540,002 seconds from the time I finish this sentence, well that’s just really disturbing. It shows that our free will, whatever it is, isn’t nearly as “free” or impressive as we thought. It would be a little like finding out that although your parents have loved you your whole life, just as you’ve always thought, they actually purchased you as a baby on the black market for the purpose of doing hideous experiments on you—but when they saw you they fell in love with you and dropped their nefarious plans. (Okay, that’s a little extreme.) In that case your judgment that they have always loved you is perfectly correct, but the fact of their original intentions casts the whole thing in a new and disturbing light. Similarly, if compatibilism and determinism are both true, then your judgment that you have (an important kind of) free will is perfectly correct, but the fact of determinism casts the whole thing in a new and disturbing light.
But hey, that’s just my opinion, for what it’s worth. What we can say, with confidence, is that the three questions we just went over are unanswered and continue to be extremely puzzling.