Over the past few years, an interesting development in experimental philosophy has been work on the “ought implies can” principle (OIC) in commonsense morality. Several research teams have investigated whether patterns in commonsense moral judgment are consistent with a commitment to OIC, understood as a conceptual entailment from having a moral responsibility to being able to fulfill it. Across a variety of contexts and testing procedures, the principal finding has been very consistent: people are definitely willing to attribute moral responsibilities to agents unable to fulfill them. Based on these findings, I and others have concluded that there is no conceptual entailment from “ought” to “can.” But there is a lingering question. If there is no conceptual entailment, then what is the source of the intuitive link, which many theorists seem to sense, between “ought” and “can”? A new paper might provide at least part of the answer.
One theory, proposed by Walter Sinnott-Armstrong, is that (moral) “ought” claims can function as both descriptions of responsibilities and as encouragement toward their fulfillment. Their descriptive function is perfectly consistent with inability, but their encouragement function is not. When I describe you as having a responsibility to fulfill your promise, my remark is perfectly consistent with your being unable to do so. In this respect, “ought” exceeds “can.” But when I encourage you to fulfill your promise, the natural interpretation of my remark suggests that I believe you can do so. In this respect, “ought” implies “can.” (Charles Pigden has traced some of this theory’s historical antecedents.)
So the theory really has two parts. One part, the dual-function hypothesis, states that “ought” claims have at least two functions: description and encouragement. Another part, the interaction hypothesis, states that the two functions relate differently to an agent’s inability to perform.
To test the theory, I ran a series of behavioral experiments. It turns out that “ought” statements can function to both describe responsibilities and encourage their fulfillment. (They can also be used to cast blame in some contexts.) This supports the dual-function hypothesis. Moreover, the two functions relate differently to whether an agent is able or unable to perform. Regardless of whether an agent can perform, people consistently interpret “ought” statements as describing responsibilities. And while people consistently interpret “ought” statements as encouragement when the agent is able to perform, they do not do so when the agent is unable to perform. This supports the interaction hypothesis.
But it’s not just that inability depresses an “ought” claim’s ability to function as encouragement. It seems to do so for a specific reason, namely, that it is not worthwhile to encourage somebody to do something that they cannot do. This is best illustrated by the following study.
Participants were assigned to one of two conditions, in which they read a story about Alex (my adorable nephew’s namesake). Alex promised to deliver a document by 4pm. In the email condition, the document is digitized and has to be emailed to the clerk’s office. Given the strong and reliable internet connection, Alex can email the document all the way up to 4pm and still deliver it on time. In the drive condition, the document is hand-signed and has to be physically delivered by driving it to the clerk’s office. Given the driving distance, if Alex leaves any later than 3pm, it is impossible for him to deliver the document on time.
So the two conditions are matched in terms of Alex’s promise to deliver the document by 4pm. But they differ in the time at which Alex becomes incapable of fulfilling the promise: 4pm in the email condition compared to 3pm in the drive condition.
Participants then performed a timeline graphing task. They were presented with a series of statements and instructed to construct timelines depicting the period during which the statements are true in the scenario. The three key statements were these:
- Alex has a responsibility to deliver/email the document by 4pm. (description)
- It is still worthwhile to encourage Alex to deliver/email the document by 4pm. (encouragement)
- Alex can still deliver/email the document by 4pm. (ability)
As you can see in the figure below, in the email condition, participants depicted all three statements as true until basically the same time: 4pm. By contrast, in the drive condition, participants depicted the responsibility as lasting until 4pm, but ability expired much earlier, at basically the same time that it was no longer worthwhile to encourage Alex to deliver — literally and figuratively! — on his promise.
Overall, then, these findings support a specific diagnosis of the intuitive appeal of OIC: it is intuitive, at least in part, because “ought” claims can function to encourage behavior, but it isn’t worthwhile to encourage people to do things they can’t do.
The findings also address some concerns that others have expressed about prior findings undermining the status of OIC in commonsense morality. The concerns pertained to alleged oddness or task demand brought on by certain questioning procedures, which allegedly complicates the interpretation of very clear and consistent patterns whereby the overwhelming majority of people attribute moral responsibility in tandem with inability. For instance, participants might agree with responsibility attributions if at any point in the scenario the agent had a responsibility, while agreeing with the ability attribution if at any point in the scenario the agent was able to perform. If so, then there might be no point in the scenario where participants attribute both responsibility and inability. But this concern cannot apply to the results from the timeline-graphing study just described. Instead of providing verbal answers that could potentially be implicitly indexed to different times in the scenario, participants graphed timelines to visually represent the time during which a statement was still true. In other words, people drew simple pictures showing that, on their understanding, some responsibilities outlast the agent’s ability to fulfill them.1