  Reasoning about observed effects and their causes is important in multi-agent
contexts. While there has been much work on causality from an objective
standpoint, causality from the point of view of some particular agent has
received much less attention. In this paper, we address this issue by
incorporating an epistemic dimension to an existing formal model of causality.
We define what it means for an agent to know the causes of an effect. Then
using a counterexample, we prove that epistemic causality is a different notion
from its objective counterpart.
