  We investigate an approach to reasoning about causes through argumentation.
We consider a causal model for a physical system, and look for arguments about
facts. Some arguments are meant to provide explanations of facts whereas some
challenge these explanations and so on. At the root of argumentation here, are
causal links ({A_1, ... ,A_n} causes B) and ontological links (o_1 is_a o_2).
We present a system that provides a candidate explanation ({A_1, ... ,A_n}
explains {B_1, ... ,B_m}) by resorting to an underlying causal link
substantiated with appropriate ontological links. Argumentation is then at work
from these various explaining links. A case study is developed: a severe storm
Xynthia that devastated part of France in 2010, with an unaccountably high
number of casualties.
