It’s one of those things that often confuse people–and not just students. Causal Determinism of the sort we talked about in class has several close-by cousins and relations which conceivably pose problems for free will and moral responsibility. But they are all different from each other, and so the the problems they pose to free will and moral responsibility aren’t the same either. Therefore, they should not be confused with each other. In this post, I will focus on just three–Causal Determinism, Predictability (or Foreknowledge), and Fatalism.

Causal Determinism–Everything that happens is causally determined to happen exactly as it does by what has already gone before. Now, what it means for event A to causally determine event B is basically that given A’s occurrence and the causal laws, B cannot not happen. So we can also restate the idea as follows–everything that happens is fixed by the past state of the universe plus the causal laws. What you want to notice is that this is a thesis about how different slices of the universe’s history (or timeline) relate to each other–that the earlier slices causally determines the later slices.

Causal determinism seems to rule out free will. Since everything that happens, including our own actions and decisions, are determined by the past and the causal laws, there is a sense in which we could have done other than what we actually did only as much as we could have made the past or laws of nature different. But this suggests that we couldn’t have done otherwise than what we do just as we couldn’t change the past or the causal laws.

Now, sometimes, the thesis of Causal Determinism is phrase with an expository device of an ‘all knowing’ predictor. To use the classic example, consider this quote from Pierre-Simon Laplace (1749-1827):

We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

Laplace isn’t the first person to talk like this. The Wikipedia page linked above mentions another writer from the 1700s. Actually, there’s at least a paragraph from Cicero (106-43 BC) that can be read in an analogous way, and Cicero was probably just channeling other thinkers in the ancient Greco-Roman world.)

But the Laplacian formulation is potentially misleading as it has the tendency to cause readers to run together two analytically distinct ideas. The first idea is Causal Determinism–the idea that the past causally determines the present and future. The second idea is Prediction, or Foreknowledge. These aren’t the same things and they don’t have to entail each other.

Predictability–What will happen can be (perfectly) foreknown/predicted beforehand. What you want to notice is that this is a thesis about what kind of knowledge about the world is in principle possible–typically not for us human beings, but for a idealized predictor or god. The thesis basically asserts that such knowledge is possible (for the idealized predictor).

Now, given Causal Determinism and certain basic assumptions, Causal Determinism entails Predictability. But even so, the two aren’t the same–in fact, it’s not difficult to set up an otherwise deterministic system and yet is also inherently non-predictable. And the reverse is certainly untrue–Predictability doesn’t entail Causal Determinism. Remember, Causal Determinism is the thesis that everything that happens is causally determined to happen exactly as it does by what has already gone before, which technically says nothing about what’s in principle knowable. Conversely, given the right kind of knower–some omniscient god, for instance–nothing prevents us from saying that the future is predictable even within a causally indeterministic universe.

Some philosophers think that Predictability rules out free will, but nonetheless, it’s not exactly for the same reason as Causal Determinism. The thought goes something like this. For argument’s sake, let’s say that the Predictor knows, now, that I am going eat an ice cream tomorrow. But whatever else that means, it means that–in truth–I really am going to eat an ice cream tomorrow. But if that’s already true, now (the day before I am supposed to eat the ice cream), it seems as if I couldn’t do other than that ice cream tomorrow. If somehow, I didn’t eat that ice cream tomorrow, it can only mean that there wasn’t the supposed knowledge in the first place; but we are assuming for the sake of the argument that there was that knowledge.

When Predictability is associated with an omniscient God, the issue can also be referred to as the problem that Divine Foreknowledge poses to free will, and this is what’s going on in the quote below from the Jewish philosopher-theologian Moses Maimonides (1135-1204):

Does God know or does He not know that a certain individual will be good or bad? If thou sayest ‘He knows’, then it necessarily follows that [that] man is compelled to act as God knew beforehand he would act, otherwise God’s knowledge would be imperfect [which is not possible]…

Note that the above focuses on the problem that Predictability (or Divine Foreknowledge) itself supposedly poses to free will–independently of something else, e.g., Causal Determinism. This means that if your predictability is the outcome of Causal Determinism, then any problem posed to free will is posed by the underlying Causal Determinism.

For the last concept–fatalism–the easiest way is to begin with a story. This one is from W. Somerset Maugham, though he surely based it on pre-existing material:

There was a merchant in Baghdad who sent his servant to market to buy provisions and in a little while the servant came back, white and trembling, and said, Master, just now when I was in the marketplace I was jostled by a woman in the crowd and when I turned I saw it was Death that jostled me. She looked at me and made a threatening gesture, now, lend me your horse, and I will ride away from this city and avoid my fate. I will go to Samarra and there Death will not find me. The merchant lent him his horse, and the servant mounted it, and he dug his spurs in its flanks and as fast as the horse could gallop he went. Then the merchant went down to the marketplace and he saw me standing in the crowd and he came to me and said, Why did you make a threatening gesture to my servant when you saw him this morning? That was not a threatening gesture, I said, it was only a start of surprise. I was astonished to see him in Baghdad, for I had an appointment with him tonight in Samarra.

Fatalism–Some things are fixed such that they will happen no matter what we do–even if we try to avoid them, they will still happen; our very attempt to avoid them may even be what makes them happen.

Let’s try to tease out what the above means through the elements in the story. First, there is some sort of ‘ending outcome’ that has been fated–there is a sense that the servant couldn’t have avoided his fate to meet death in Samarra that night no matter what he did. Typically, not everything is fated but only some significant outcome. Second, the story makes no commitment as to whether the servant could have done other than what he did on the way to his fate. The story makes perfect sense even if–because of indeterminism, for instance–the servant really could have stayed in Baghdad rather than go off to Samarra. This means that Fatalism is orthogonal to Causal Determinism –it’s conceptually possible for something to be fated in a causally deterministic, or a causally indeterministic universe. Third, is the idea that the servant met his fate at least partly because of his very attempt to avoid it–that’s the other part of the irony in the passage. Finally, the story is also neutral on whether it is in principle known that the thing fated will happen–not even Death knew–and whether it is known or not, it’s not the knowledge that’s making the fate unavoidable. In short Fatalism needs to be distinguished from both Causal Determinism and Predictability (and Foreknowledge).

While Fatalism doesn’t straightforwardly rule out free will (since, as pointed out previously, it’s orthogonal to determinism and indeterminsm), it does appear to pose a threat to moral responsibility. At first glance at least, it doesn’t seem like we can be morally responsible for an outcome that we cannot avoid. I don’t think that’s quite right, but intuitively, you might have that feeling. But whatever the case, the point is that if Fatalism poses a threat to moral responsibility, it doesn’t quite do so in the same way that Causal Determinism and Predictability do.