PHI403 Lecture 16 — What is Probabilistic Causation?

On ontological probability: what makes probability claims true? Two main philosophical answers:

Frequentism — probabilities are defined by long-run frequencies. Fits Humean causation: a 60 % chance of E given C just is the fact that E follows C in 60 % of trials. Observable from data, in principle.
Propensity theory — probabilities are intrinsic tendencies of individuals or situations. Fits dispositionalism: real-world properties produce frequencies.

The course's critical move: applying a population frequency directly to an individual case is the ecological fallacy. Frequentism presupposes every individual case is the statistical average of its reference population. Choosing narrower sub-groups (all the way to N=1) is then indicated — which leads to singularism and a propensity view.

Not all propensity theorists are singularists. Long-run propensity theory (Donald Gillies) holds propensities reveal themselves through frequencies at scale. Still, probability is intrinsic.

Overdisposing: a power may have enough strength to guarantee the effect "twice over" while still not manifesting (because interferers can block it). Classical probabilities are bounded by [0, 1]; propensities are not — which is another argument for their ontological distinctness from frequencies.

Connections

Back-link: sources/2023-anjum-rocca-phi403-causation-in-science. Concepts: concepts/probabilistic-causation · concepts/dispositionalism · concepts/rct-limitations · concepts/regularity-theory-of-causation.