Introduction

Two uncontroversial claims: First, time sometimes seems to pass more slowly than normal, and sometimes seems to pass more quickly than normal. So what is in fact an interval of, say, five minutes sometimes seems longer or shorter than another interval of five minutes. Second, it’s better when a pain lasts for a shorter duration than a longer duration, all else equal.

But what is relevant to the badness of a given pain—its actual duration, or its subjective duration? For example, compare (1) and (2), where p is a pain and r is a rate:

1. Experiencing p for 5 minutes while time subjectively passes at r.
2. Experiencing p for 10 minutes while time subjectively passes at 2r.

Is (1) less bad than (2), because the pain lasts for a shorter amount of time, or are they equally bad, because in both cases the pain seems to last for the same amount of time?

Call those who give the first answer ‘objectivists’, and those who give the second answer ‘subjectivists’. Of course, you could ask a corresponding question about pleasure. In general, objectivists think that the intrinsic value of an experience is proportional to its actual duration, and subjectivists think that the intrinsic value of an experience is proportional to its subjective duration.

In this post I’ll first say why it matters whether objectivism or subjectivism is true, and then explain why I accept subjectivism.

Why it matters which view is true

Pessimism: Subjectivism lends support to pessimism. Which times seem to last the longest? Those that are the most agonizing. Which times seem to last the shortest? Those that are the most enjoyable. Now suppose that subjectivism is true. Then the long-seeming pains are bad in proportion to their subjective duration, which is much longer than their objective duration. Similarly, the short-seeming pleasures are good in proportion to their subjective duration, which is much shorter than their objective duration. So the badness of everything bad that we experience is magnified, and the goodness of everything good that we experience is diminished.

Animal ethics: It’s plausible that different species experience time at different rates. Suppose, say, that cows experience time at twice the rate of chickens. And suppose that subjectivism is true. Then all else equal, it’s better for a cow to experience a given pain for five minutes than for a chicken to experience the same pain for five minutes, since the pain will seem to last twice as long to the chicken. This effect might be even greater between other animals. For example, maybe turtles experience time at a thousand times the rate of humming birds.

AI ethics: We may be able to create conscious AI systems that experience time at rates very different from us. All the considerations from animal ethics apply here, where the AI systems can be thought of as species of animals. Beyond this, if the AI systems are moral agents and it is appropriate to punish them for wrongdoing, then subjectivism and objectivism may entail that different lengths of punishment are just.¹ This could make the difference between a sentence that lasts for seconds and a sentence that lasts for years.

Human enhancement: Suppose that subjectivism is true. Then doubling the rate at which time seems to pass while someone is experiencing a pain is as good as halving the actual duration of the pain. Similarly, halving the rate at which time seems to pass while someone is experiencing a pleasure is as good as doubling the actual duration of the pleasure. In the future we may have the ability to alter the rates at which time seems to pass to us without otherwise affecting the quality of our experiences. If subjectivism is true, then we can use this ability to increase the value of our pleasures and decrease the disvalue of our pains. But if objectivism is true, then there would be no benefit to decreasing the subjective duration of a pain or increasing the subjective duration of a pleasure.

Utilitarianism: In his foundational text on utilitarianism, Bentham says that “the value of a pleasure or pain…will be greater or less according to…its duration” (in addition to its “intensity”, “certainty or uncertainty”, and “propinquity or remoteness”).² But he doesn’t say whether this is its actual duration or its subjective duration. This makes a big difference, partly for the reasons given above. So utilitarians should be especially concerned with whether objectivism or subjectivism is true.

An argument for subjectivism

There’s a simple argument for subjectivism. It relies on the following principle:

If what it’s like to experience e1 is exactly the same as what it’s like to experience e2, then the intrinsic value of e1 equals the intrinsic value of e2.

The idea behind the principle is that the intrinsic value of an experience depends solely on what it’s like to experience it. So the intrinsic badness of a pain depends solely what it’s like to experience the pain, and the intrinsic goodness of a pleasure depends solely on what it’s like to experience the pleasure.

Now think back to (1) and (2) from above. What it’s like to experience the pain for 5 minutes while time subjectively passes at r is exactly the same as what it’s like to experience the pain for 10 minutes while time subjectively passes at 2r. (This follows from what it means for time to subjectively pass at a given rate.) So by the above principle, the pains have the same intrinsic value, which is what subjectivists claim.

An argument for objectivism

Despite the argument for subjectivism, I still have a lingering feeling that there is something worse about the objectively longer pain. I think this feeling is ultimately motivated by the following misguided argument for objectivism.

The basic idea behind the argument is that talk about the objective duration of an experience is interchangeable with talk about its quantity. How? Well, instead of saying that I experienced one pain that lasted for five minutes, we can say that I experienced five pains successively, each of which lasted for one minute. Or that I experienced three hundred pains successively, each of which lasted for one second. And so on, until we get to some arbitrarily small unit. This might be an odd way of talking, but it’s not incorrect.

If we talk this way, then what we previously would have described as an objectively longer pain we now describe simply as more pain. But it’s uncontroversial that more pain is worse than less pain. So the 10 minutes of pain is more pain than the 5 minutes of pain, since there’s (objectively) more of it, which in turn makes it worse. And this is what objectivists claim.

The problem with the argument is that “more pain is worse than less pain” is true only if all else is equal. But in the relevant cases (for example, 5 minutes of pain at r vs. 10 minutes of pain at 2r) not all else is equal: the the subjective rate of the passage of time is different while each pain is being experienced. And whether this affects the value of the pains is precisely what is in question in the debate between subjectivists and objectivists.