Why did the dark matter hypothesis supersede modified gravity in the 1980s?

TL;DR

In the 1980s, the scientific community favored dark matter over modified gravity due to its superior problem-solving potential, compatibility with existing theories, and testability, leading to its dominance in explaining cosmic anomalies.

Contribution

This paper provides an integrated historical and philosophical analysis explaining why dark matter became the preferred hypothesis over modified gravity in the 1980s.

Findings

Dark matter hypothesis had greater problem-solving potential.

Dark matter was more compatible with established theories.

Dark matter was more independently testable.

Abstract

In the 1960s and 1970s a series of observations and theoretical developments highlighted the presence of several anomalies which could, in principle, be explained by postulating one of the following two working hypotheses: (i) the existence of dark matter, or (ii) the modification of standard gravitational dynamics in low accelerations. In the years that followed, the dark matter hypothesis as an explanation for dark matter phenomenology attracted far more attention compared to the hypothesis of modified gravity, and the latter is largely regarded today as a non-viable alternative. The present article takes an integrated history and philosophy of science approach in order to identify the reasons why the scientific community mainly pursued the dark matter hypothesis in the years that followed, as opposed to modified gravity. A plausible answer is given in terms of three epistemic criteria for the pursuitworthiness of a hypothesis: (a) its problem-solving potential, (b) its compatibility with established theories and the feasibility of incorporation, and (c) its independent testability. A further comparison between the problem of dark matter and the problem of dark energy is also presented, explaining why in the latter case the situation is different, and modified gravity is still considered a viable possibility.