“It’s hard not to do philosophy”

A pressure wave in the air, a set of equations, or scratches on a clay tablet: “Such physical or formal things can refer to something beyond themselves,” Neil Dewar says. “They can carry a sentence, describe a planet’s motion, record a debt or represent a physical theory.” Dewar is interested in how this is possible: how one thing can stand for another, and how meaning arises. Philosophers call this the question of “aboutness”, a mystery that, Dewar says, has stayed with him throughout his career.

Neil Dewar is an Associate Professor at the Faculty of Philosophy at the University of Cambridge and an alumnus of LMU. His research brings together philosophy, physics, logic and the philosophy of science. At its centre is the role of mathematical representation in physics. “Physical theories use equations, models and mathematical structures, allowing scientists to calculate, predict and test claims about reality. But they also raise a philosophical question: how does mathematics come to represent the physical world?” For Dewar, this is not only a technical question, but one about meaning.

Born in Scotland, he studied Physics and Philosophy at Oxford, a joint programme combining the two subjects. He had considered physics, perhaps mathematics, but also subjects such as philosophy or politics. “When I came across the combined programme, it seemed like a good way of deferring that decision,” he says, laughing.

Impolite letters between physicists

Enlarge

The combination of physics and philosophy remained central to Dewar’s academic path. He went on to complete further graduate work in philosophy at Oxford, where he received his doctorate with a thesis on “Symmetries in Physics, Metaphysics, and Logic”. After Oxford and a Procter Fellowship at Princeton, Dewar joined the Munich Center for Mathematical Philosophy (MCMP) at LMU in 2016 as an Assistant Professor. There, he completed his Habilitation on questions of structure, symmetry and equivalence in physical theories. In 2021, he was appointed to the University of Cambridge, where he is now a University Associate Professor at the Faculty of Philosophy and a Fellow of Trinity Hall.

Among the questions Dewar investigates at Cambridge is what might be called a translation problem. “In physics, the same processes can often be described in more than one mathematical way,” he says. “I study when such different formulations are simply different languages for the same thing, and when they actually involve different assumptions about space, time or the laws of nature.”

A famous example comes from the early days of quantum theory. “Werner Heisenberg’s matrix mechanics and Erwin Schrödinger’s wave mechanics first appeared to offer very different ways of understanding the quantum world,” Dewar explains. “At the time, physicists wrote very impolite letters to one another about how dreadful the other formulation was.” Today, however, the two approaches are understood as different mathematical formulations of the same underlying theory. “Such cases show why it matters to ask how physical content is represented, and how we recognise when different descriptions are, in fact, saying the same thing.”

Physics as a living language

Physics, he says, is “philosophically powerful” because it combines mathematical precision with a direct connection to the real world. “Its models don’t rely on tone, connotation or suggestion in the way ordinary language does.” At the same time, they allow scientists to calculate, predict and test claims about reality. Physics is, as Dewar puts it, a “living language”: a precise mathematical language used to describe the world.

In his everyday research, he often begins with a problem from the literature, sometimes contemporary, sometimes historical, and sometimes from his teaching. “When explaining a concept to students, I sometimes realise that it is not yet as clear to me as I would like,” he says. “And that may become the starting point for further research.”

When working on a philosophical problem, Dewar doesn’t always begin by asking whether a claim is right or wrong. “Often, the first step is to ‘nail down’ what it actually means,” he explains. “What would it mean, for example, to say that spacetime geometry is conventional? And how could one make that idea precise?”

“Mathematical toy models”

From there, Dewar often turns to mathematical “toy models”: simple examples that isolate the core of a philosophical problem or idea. “Once I understand these, I begin to see what is happening philosophically and build an explanation.” In the early stages, his work is often done by hand. “I like scribbling on blank sheets of printer paper, working through ideas, examples and arguments as they take shape.” Later, he writes on a laptop, directly in LaTeX, a typesetting system often used for mathematical and scientific texts. “And then, of course, comes the rewriting,” he says, “often several times.”

Rather than presenting only polished results at conferences, Dewar often brings projects to reading groups or smaller workshops while they are still “half-baked”, as he puts it. “This is quite common in philosophy, because discussion can help us get clearer about our ideas.”

At LMU, Dewar found an environment well suited to this kind of work. Thinking back to his time in Munich, he recalls a “friendly, collaborative and supportive” atmosphere at the MCMP. “Its intellectual environment was a good place for ‘bouncing ideas around’,” he says. “There was always someone willing to talk through a problem at a whiteboard. And because many people have a mathematical background, we shared a common language and could dive right in.” He also remembers the centre as a lively intellectual setting, with researchers from across Europe and the United States constantly passing through and new conversations beginning.

Time and space for ideas

His time at LMU also included a stay as a Researcher in Residence at the Center for Advanced Studies (CAS), a programme designed to give early-career scholars time, space and an interdisciplinary setting for their own research. “The period at the CAS was very helpful for me,” Dewar recalls. “Without teaching commitments, I was able to make good progress on several research projects, and the opportunity to bring researchers to Munich to develop collaborations with them was extremely valuable.” In his spare time in Munich, Neil Dewar enjoyed hiking in the Bavarian Alps. “I once climbed the Zugspitze with a couple of friends, which was great fun.”

Cambridge, where he works today, is another place with a long tradition in both philosophy and science. Here, Dewar is based in the Faculty of Philosophy. “But the university also has a Department of History and Philosophy of Science, giving me access to two intellectual communities.”

In Cambridge, broader teaching has been valuable for his research. “Supervising students on thinkers such as Frege or Wittgenstein, for example, can open up unexpected connections, even if they are not central to my everyday work,” he says. Cambridge also brings him into closer contact with philosophers working in quite different areas, including ethics and aesthetics. Both environments, Cambridge and Munich, have been stimulating in their own way, he says.

Philosophy in everyday life

“What I’d love non-philosophers to see is that it is harder not to do philosophy than they might think.” For example, a conversation about whether one should fly less or become vegetarian because of climate change soon leads into difficult questions in ethics. A disagreement, in which one person thinks they were misunderstood, raises questions in the philosophy of language. And current debates about large language models quickly become questions in the philosophy of mind.

“If philosophy looks abstract, obscure or remote, it’s because it steps back from such individual cases and asks about the general principles behind them,” Dewar says. “But the philosophical problems themselves are not detached from ordinary life. They inevitably arise from it.”