Causal models and algorithmic fairness

Beigang, Fabian (2023) Causal models and algorithmic fairness. PhD thesis, London School of Economics and Political Science.

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Abstract

This thesis aims to clarify a number of conceptual aspects of the debate surrounding algorithmic fairness. The particular focus here is the role of causal modeling in defining criteria of algorithmic fairness. In Chapter 1, I argue that in the discussion of algorithmic fairness, two fundamentally distinct notions of fairness have been conflated. Subsequently, I propose that what is usually taken to be the problem of algorithmic fairness should be divided into two subproblems, the problem of predictive fairness, and the problem of allocative fairness. At the core of Chapter 2 is the proof of a theorem that establishes that three of the most popular (predictive) fairness criteria are pairwise incompatible. In particular, I show that under certain conditions, a predictive algorithm that satisfies a criterion called counterfactual fairness will with logical necessity violate two other popular predictive fairness criteria called equalized odds and predictive parity. In Chapter 3, a new predictive fairness criterion is developed using a mathematical framework for causal modeling. This fairness criterion, which I call causal relevance fairness, is a relaxation of another popular fairness criterion, counterfactual fairness, but turns out to be more closely in line with philosophical theories of discrimination. In Chapter 4, another infamous impossibility result in algorithmic fairness is analyzed through the lens of causality. I argue that by using a causal inference method called matching, we can modify the two fairness criteria equalized odds and predictive parity in a way that resolves the impossibility. Lastly, Chapter 5 contains an empirical case study. In it, the fairness of a popular recidivism risk prediction tool is analyzed using the criteria of (predictive) fairness developed earlier.

Item Type:	Thesis (PhD)
Additional Information:	© 2023 Fabian Beigang
Library of Congress subject classification:	B Philosophy. Psychology. Religion > B Philosophy (General) Q Science > Q Science (General) Q Science > QA Mathematics
Sets:	Departments > Philosophy, Logic and Scientific Method
Supervisor:	List, Christian and Bradley, Richard and Bright, Liam Kofi
URI:	http://etheses.lse.ac.uk/id/eprint/4568

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