The Knobe Effect and the Intentionality of Side Effects

Imagine that the chairman of a company decides to implement an initiative that will reap profits for his company but will also have a particular side effect. The chairman knows the side effect will occur, but he couldn’t care less. Making money is his only reason for making his decision.

The chairman goes forward with the initiative, his company makes a lot of money, and the side effect occurs as anticipated.

Did the chairman bring about the side effect intentionally? Don’t answer yet.

In a famous 2003 experiment, the philosopher Joshua Knobe showed that people’s judgments about whether a side effect is intentional or not depend on what the side effect is. He randomly assigned subjects to read one of two scenarios, which were the same as the one above, except the actual side effects of the chairman’s decision were presented. In the first scenario, the initiative harms the environment. In the second, it helps the environment.

Of the subjects who read the scenario in which the initiative harmed the environment, 82% said the chairman intentionally brought about the harm. Subjects made the opposite judgment in the other condition. Asked whether the chairman intentionally helped the environment by undertaking the initiative, 77% said that he didn’t.

So, there is an asymmetry in the way we ascribe intentionality to side effects – now known as the “Knobe Effect” or the “Side Effect Effect” – and this study suggests that it stems from our moral evaluations of those side effects. As Knobe concluded in the 2003 study, people “seem considerably more willing to say that a side-effect was brought about intentionally when they regard that side-effect as bad than when they regard it as good.”

But subsequent research by Knobe and others has shown that it’s not that simple. Sometimes people judge good side effects, such as when an action violates an unjust Nazi law, as intentional and bad side effects, like complying with the Nazi law, as not intentional. Richard Holton argues that it is whether a norm is knowingly violated, and not necessarily whether a side effect is morally good or bad, that influences people’s judgments of intentionality.

You probably would’ve struggled to say whether the chairman intended the “particular side effect” because there was nothing to guide your intuitions. If there were, though, you likely would’ve exemplified the Knobe Effect.