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Experiments that test physics and philosophy as “a single whole,” Amanda Gefter suggests, may be our only route to surefire knowledge about the universe…

Metaphysics is the branch of philosophy that deals in the deep scaffolding of the world: the nature of space, time, causation and existence, the foundations of reality itself. It’s generally considered untestable, since metaphysical assumptions underlie all our efforts to conduct tests and interpret results. Those assumptions usually go unspoken.

Most of the time, that’s fine. Intuitions we have about the way the world works rarely conflict with our everyday experience. At speeds far slower than the speed of light or at scales far larger than the quantum one, we can, for instance, assume that objects have definite features independent of our measurements, that we all share a universal space and time, that a fact for one of us is a fact for all. As long as our philosophy works, it lurks undetected in the background, leading us to mistakenly believe that science is something separable from metaphysics.

But at the uncharted edges of experience — at high speeds and tiny scales — those intuitions cease to serve us, making it impossible for us to do science without confronting our philosophical assumptions head-on. Suddenly we find ourselves in a place where science and philosophy can no longer be neatly distinguished. A place, according to the physicist Eric Cavalcanti, called “experimental metaphysics.”

Cavalcanti is carrying the torch of a tradition that stretches back through a long line of rebellious thinkers who have resisted the usual dividing lines between physics and philosophy. In experimental metaphysics, the tools of science can be used to test our philosophical worldviews, which in turn can be used to better understand science. Cavalcanti, a 46-year-old native of Brazil who is a professor at Griffith University in Brisbane, Australia, and his colleagues have published the strongest result attained in experimental metaphysics yet, a theorem that places strict and surprising constraints on the nature of reality. They’re now designing clever, if controversial, experiments to test our assumptions not only about physics, but about the mind.

While we might expect the injection of philosophy into science to result in something less scientific, in fact, says Cavalcanti, the opposite is true. “In some sense, the knowledge that we obtain through experimental metaphysics is more secure and more scientific,” he said, because it vets not only our scientific hypotheses but the premises that usually lie hidden beneath…

Gefter traces the history of this integrative train of thought (Kant, Duhem, Poincaré, Popper, Einstein, Bell), its potential for helping understand quantum theory… and the prospect of harnessing AI to run the necessary experiments– seemingly comlex and intensive beyond the scope of currenT experimental techniques…

Cavalcanti… is holding out hope. We may never be able to run the experiment on a human, he says, but why not an artificial intelligence algorithm? In his newest work, along with the physicist Howard Wiseman and the mathematician Eleanor Rieffel, he argues that the friend could be an AI algorithm running on a large quantum computer, performing a simulated experiment in a simulated lab. “At some point,” Cavalcanti contends, “we’ll have artificial intelligence that will be essentially indistinguishable from humans as far as cognitive abilities are concerned,” and we’ll be able to test his inequality once and for all.

But that’s not an uncontroversial assumption. Some philosophers of mind believe in the possibility of strong AI, but certainly not all. Thinkers in what’s known as embodied cognition, for instance, argue against the notion of a disembodied mind, while the enactive approach to cognition grants minds only to living creatures.

All of which leaves physics in an awkward position. We can’t know whether nature violates Cavalcanti’s [theorem] — we can’t know, that is, whether objectivity itself is on the metaphysical chopping block — until we can define what counts as an observer, and figuring that out involves physics, cognitive science and philosophy. The radical space of experimental metaphysics expands to entwine all three of them. To paraphrase Gonseth, perhaps they form a single whole…

“‘Metaphysical Experiments’ Probe Our Hidden Assumptions About Reality,” in @QuantaMagazine.

* Johann Wolfgang von Goethe

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As we examine edges, we might send thoughtful birthday greetings to Rudolf Schottlaender; he was born on this date in 1900. A philosopher who studied with Edmund Husserl, Martin Heidegger, Nicolai Hartmann, and Karl Jaspers, Schottlaender survived the Nazi regime and the persecution of the Jews, hiding in Berlin. After the war, as his democratic and humanist proclivities kept him from posts in philosophy faculties, he distinguished himself as a classical philologist and translator (e.g., new translations of Sophocles which were very effective on the stage, and an edition of Petrarch).

But he continued to publish philosophical and political essays and articles, which he predominantly published in the West and in which he saw himself as a mediator between the systems. Because of his positions critical to East Germany, he was put under close surveillance by the Ministry for State Security (Ministerium für Staatssicherheit or Stasi)– and inspired leading minds of the developing opposition in East Germany.

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