Counterfactually Fair Representation
Zhiqun Zuo Mohammad Mahdi Khalili Xueru Zhang
The use of machine learning models in high-stake applications (e.g.,
healthcare, lending, college admission) has raised growing concerns due to
potential biases against protected social groups. Various fairness notions and
methods have been proposed to mitigate such biases. In this work, we focus on
Counterfactual Fairness (CF), a fairness notion that is dependent on an
underlying causal graph and first proposed by Kusner \textit{et
al.}~\cite{kusner2017counterfactual}; it requires that the outcome an
individual perceives is the same in the real world as it would be in a
"counterfactual" world, in which the individual belongs to another social
group. Learning fair models satisfying CF can be challenging. It was shown in
\cite{kusner2017counterfactual} that a sufficient condition for satisfying CF
is to \textbf{not} use features that are descendants of sensitive attributes in
the causal graph. This implies a simple method that learns CF models only using
non-descendants of sensitive attributes while eliminating all descendants.
Although several subsequent works proposed methods that use all features for
training CF models, there is no theoretical guarantee that they can satisfy CF.
In contrast, this work proposes a new algorithm that trains models using all
the available features. We theoretically and empirically show that models
trained with this method can satisfy CF\footnote{The code repository for this
work can be found in
\url{https://github.com/osu-srml/CF_Representation_Learning}}.