Extreme event attribution is an exercise in causality. Rather than some deep philosophical statement, an attribution statement is a probabilistic one. However, it is also a conditional statement and is incomplete if the conditions and uncertainties are not clearly specified. We will review a hierarchy of extreme attribution statements types and their uncertainties ranging from those with very few conditions to those that are highly constrained. Real world examples will include interpretations of recent attributions statements about Hurricanes Harvey, Maria and Irma. In particular, we will explore the confidence in the human induced portion of the Harvey’s record rainfall in the greater Houston area by examining five independent analyses.