It's not a stretch to suggest that when we disagree with other people, we often regard them as being irrational. Kevin Dorst PhD '19 has developed a body of research with surprising things to say about that.
Dorst, an associate professor of philosophy at MIT, studies rationality: how we apply it, or think we do, and how that bears out in society. The goal is to help us think clearly and perhaps with fresh eyes about something we may take for granted.
Throughout his work, Dorst specializes in exploring the nuances of rationality. To take just one instance, consider how ambiguity can interact with rationality. Suppose there are two studies about the effect of a new housing subdivision on local traffic patterns: One shows there will be a substantial increase in traffic, and one shows a minor effect. Even if both studies are sound in their methods and data, neither may have a totally airtight case. People who regard themselves as rationally assessing the numbers will likely disagree about which is most valid, and - though this may not be entirely rational - may use their prior beliefs to poke holes in the study that does not represent their prior beliefs.
Among other things, this process also calls into question the widespread "Bayesian" conception that people's views shift and come into alignment as they're presented with new evidence. It may be that instead, people apply rationality while their views diverge, not converge.
This is also the kind of phenomenon Dorst explores in the paper "Rational Polarization," published in The Philosophical Review in 2023; currently Dorst is working on a book about how people can take rational approaches but still wind up with different conclusions about the world. Dorst combines careful argumentation, mathematically structured descriptions of thinking, and even experimental evidence about cognition and people's views, an increasing trend in philosophy.
"There's something freeing about how methodologically open philosophy is," says Dorst, a good-humored and genial conversationalist. "A question can be philosophical if it's important and we don't yet have settled methods for answering it, because in philosophy it's always okay to ask what methods we should be using. It's one of the exciting things about philosophy."
For his research and teaching, Dorst was awarded tenure at MIT last year.
Show me your work
Dorst grew up in Missouri, not exactly expecting to become a philosopher, but he started following in the academic trail of his older brother, who had become interested in philosophy.
"We didn't know what philosophy was growing up, but once my brother started getting interested, there was a little bootstrapping, egging each other on, and having someone to talk to," Dorst says.
As an undergraduate at Washington University in St. Louis, Dorst majored in philosophy and political science. By graduation, he had become sold on studying philosophy full-time, and was accepted into MIT's program as a doctoral student.
At the Institute, he started specializing in the problems he now studies full-time, about how we know things and how much we are thinking rationally, while working with Roger White as his primary adviser, along with faculty members Robert Stalnaker and Kieran Setiya of MIT and Branden Fitelson of Northeastern University.
After earning his PhD, Dorst spent a year as a fellow at Oxford University's Magdalen College, then joined faculty of the University of Pittsburgh. He returned to MIT, this time on the faculty, in 2022. Now settled in the MIT philosophy faculty, Dorst tries to continue the department's tradition of engaged teaching with his students.
"They wrestle like everyone does with the conceptual and philosophical questions, but the speed with which you can get through technical things in a course is astounding," Dorst says of MIT undergraduates.
New methods, time-honored issues
At present Dorst, who has published widely in philosophy journals, is grinding through the process of writing a book manuscript about the complexity of rationality. Chapter subjects include hindsight bias, confirmation bias, overconfidence, and polarization.
In the process, Dorst is also developing and conducting more experiments than ever before, to look at the way people process information and regard themselves as being rational.
"There's this whole movement of experimental philosophy, using experimental data, being sensitive to cognitive science and being interested in connecting questions we have to it," Dorst says.
In his case, he adds, "The big picture is trying to connect the theoretical work on rationality with the more empirical work about what leads to polarization," he says. The salience of the work, meanwhile, applies to a wide range of subjects: "People have been polarized forever over everything."
As he explains all of this, Dorst looks up at the whiteboard in his office, where an extensive set of equations represents the output of some experiments and his ongoing effort to comprehend the results, as part of the book project. When he finishes, he hopes to have work broadly useful in philosophy, cognitive science, and other fields.
"We might use some different models in philosophy," he says, "but let's all try to figure out how people process information and regard arguments."
