  As algorithms are increasingly used to make important decisions that affect
human lives, ranging from social benefit assignment to predicting risk of
criminal recidivism, concerns have been raised about the fairness of
algorithmic decision making. Most prior works on algorithmic fairness
normatively prescribe how fair decisions ought to be made. In contrast, here,
we descriptively survey users for how they perceive and reason about fairness
in algorithmic decision making.
  A key contribution of this work is the framework we propose to understand why
people perceive certain features as fair or unfair to be used in algorithms.
Our framework identifies eight properties of features, such as relevance,
volitionality and reliability, as latent considerations that inform people's
moral judgments about the fairness of feature use in decision-making
algorithms. We validate our framework through a series of scenario-based
surveys with 576 people. We find that, based on a person's assessment of the
eight latent properties of a feature in our exemplar scenario, we can
accurately (> 85%) predict if the person will judge the use of the feature as
fair.
  Our findings have important implications. At a high-level, we show that
people's unfairness concerns are multi-dimensional and argue that future
studies need to address unfairness concerns beyond discrimination. At a
low-level, we find considerable disagreements in people's fairness judgments.
We identify root causes of the disagreements, and note possible pathways to
resolve them.
