Mathematics is a powerful tool. But increasingly, maths is being mistaken for reality. From fitness trackers to large language models, we're increasingly ruled by systems that quantify without understanding. In this incisive and darkly comic article, novelist and essayist Joanna Kavenna explores the rise of cyber-Pythagoreanism—the belief that reality can be captured through numbers—and argues that when we mistake data for truth, we risk replacing the real world with algorithmic fiction.

"Oh, Wise One, your step count today is 210. Your step distance is 0.15KM. Your moves are 3/220KCAL."

This article is about mathematical idealism: the idea that mathematical entities and/or concepts are the fundamental units of reality. The philosopher, scientist, and poet Raymond Tallis calls this ‘industrial-strength Pythagoreanism’. The phrase draws on a remark attributed to Pythagoras, ‘All is Number’. In this essay, I’ll focus more specifically on cyber-Pythagoreanism: the realm of predictive algorithms, LLMs such as ChatGPT, and two associated paradoxes, which I call (a) the ‘Map without a Territory’ and (b) the ‘Word is Number’.

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MassivelyFit addresses me as ‘Oh Wise One’ due to an error. Mine.

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However, I want to clarify that this essay is not anti-mathematics. I am not waving a banner saying, ‘Down with Math’. Even to create that banner, I would need Math - to purchase the materials, measure the paper, etc. Mathematical calculations are essential if we want to earn a living, build a house, fly a plane, launch a rocket, make predictions about the weather, feed our families, pay the rent, etc. If I am about to board a plane and a novelist emerges from the cockpit, assuring me that they will handle this flight with nothing but the power of their imagination, I will briskly alter my travel arrangements. Math is fundamental to the quantitative assessment of reality. However, when we turn to the qualitative assessment of reality, things change. At least, they should. As above, this article is concerned with cyber-Pythagoreanism, a contemporary version of mathematical idealism in which the quantitative is mistaken for, or assumed to be synonymous with, the qualitative. The result of this taxonomical mismatch is that the real is mistaken for the unreal, and vice versa.

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Let’s turn to the lines I quoted above: ‘Oh Wise One…’ etc. I have a fitness app that was pre-installed on my phone. To avoid singling out any specific tech company, I’ll call this MassivelyFit. You may have something similar on your phone. MassivelyFit addresses me: ‘Oh, Wise One, let’s try to achieve your fitness goals together’. It politely informs me of my daily step count and urges me to do more steps. 10,000 steps is good, 5,000 steps is not so good, zero steps is not good.

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Reality is ignored in favour of algorithmic fictions, which are mistaken for objective facts.

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