Through the analysis of the world-famous book by Rachel Carson, I set out to defend three theses concerning ecological science: 1)scientists should not be wary of crossing the line between facts and values, since dialectical rationality clearly shows that including moral values in scientific debates does not make science irrational or biased. On the contrary, if scientists are committed to a moral value, it is altogether rational for them to state it explicitly if this is required in a dialogue; 2) some scientific terms in ecology are “thick” in the sense that they have both a descriptive and a moral import. For positivists this implies that the language of ecology itself is biased, but I shall argue that this conclusion is not reasonable; 3)in order to be a good scientific advisor the ecologist must also have a good command of the moral discourse. None of my arguments infringe the so-called Hume’s law. Rather I shall show that facts and values are strongly intermingled in ecological science independently of the law.