---
date: '2024-01-08'
description: causal determinism as the thesis that the past and the laws of nature fix the future, why it differs from predictability, and the unrelated joke called nominative determinism.
id: Determinism
modified: 2026-10-22 11:10:00 GMT-04:00
tags:
  - philosophy
  - computing
title: Determinism
created: '2024-01-08'
published: '2024-01-08'
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slug: thoughts/Determinism
permalink: https://aarnphm.xyz/thoughts/Determinism.md
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full: https://aarnphm.xyz/llms-full.txt
---
Notes from Carl Hoefer’s [Causal Determinism](https://plato.stanford.edu/entries/determinism-causal/) entry in the Stanford Encyclopedia of Philosophy.

## causal

> Causal determinism is, roughly speaking, the idea that every event is necessitated by antecedent events and conditions together with the laws of nature.

Stated as a property of a world: if two possible worlds obey the same laws and agree completely at one time, they agree at every later time. The idea is ancient. It first received clarification and mathematical analysis in the eighteenth century, when Laplace imagined an intellect that knew every position and force at one instant and could compute the whole future from them.

Hoefer notes two places where determinism matters. One is physics and its explanatory ambitions. The other is human free action, which ties it to [[thoughts/Agency|agency]]. In both, there is no agreement over _whether determinism is true_, or over what it would mean for agency in either {{sidenotes[case]: or even whether it can be known true or false.}}

## determinism is not predictability

Determinism is a claim about the world. Predictability is a claim about what we can compute from what we can measure. The two come apart. In a [[thoughts/Chaos|chaotic]] system such as the Lorenz equations, the future is fixed by the present state, but a small error in measuring that state grows exponentially. So the prediction fails after a finite horizon, while the system stays deterministic. Laplace’s intellect needs infinite precision, and we do not have it.

## nominative determinism

A different and humorous use of the word, named in _New Scientist_’s Feedback column in 1994:

> people tend to gravitate towards areas of work or interest that fit their name.

It has no connection to causal determinism, apart from the name.