The philosopher Bernard Williams distinguished between thick ethical concepts such as “brave” and “brutal,” which have both descriptive and evaluative content, and thin ethical concepts such as “right” and “wrong,” which are purely evaluative. “Murder” and “exploitation” are thick ethical concepts that sometimes play a central role in ethical debate. They have descriptive content combined with a negative evaluation: murder and exploitation are wrong.
This duality of thick moral words, their descriptive/normative Janus face, makes them an impelling part of the vocabulary of most, if not all, ideological movements. If you oppose X, and can demonstrate that X, in fact, involves murder or exploitation (descriptive aspect), then you have immediately demonstrated that X must be opposed (normative aspect). Thick ethical concepts are often used in conflictual situations to legitimize violent actions against people who are described as intriguing, murderous, exploitive, and much else. Since the words are taken to describe reality as it is, such bad individuals must be watched over and, if necessary, acted against.
Thick moral words thus easily lend themselves to functioning as ideological firearms. Their descriptive aspect allows taking aim. Their evaluative aspect says, “Fire!” I want to mention three further dangers of thick ethical concepts.
Dogmatism. The first is that it is difficult to raise questions about their applicability, since it can appear as if you questioned the evaluative component. Let us say that you raise the question if embryo destruction really constitutes murder. In the eyes of those who take this description for reality, you appear like a treacherous person who shrewdly argues that murder might be right! Simply raising the question, no matter how open-mindedly you do it, places you in the firing line. Your very open-mindedness speaks against you: “Murder is not something to be open-minded about!”
Righteousness. A second troublesome feature is that thick ethical concepts produce instant goodness in any ideological movement. Any ideology is on the right side, regardless of which side it is on, since it fights for what its moral vocabulary unites with the good, and fights against what its vocabulary unites with the bad. Any ideology has the right and the duty to act resolutely against what its dualistic vocabulary picks out as impermissible features of reality. – Which side for peace are you on?
Suffering. A third problem is that thick moral words produce suffering in the form of gnawing suspicions and fears. Since we are not omniscient, there is much we do not know, for example, about embryonic stem cell research. Thick ethical concepts here tend to appear in our heads as stand-ins for reality. They appear in the form of an inner voice that tells us what stem cell research is. This is not a purely descriptive “is,” but a double-edged one, for what the voice in the head says the research is can be a nightmarish, “It is murder.” Since we are ignorant of much, but not of our anxiety, we cannot shake off the worrying double-edged concepts that spin in the head. They seem validated by the gnawing anxiety they produce, and we suffer without end, caught in a whirlpool of thick descriptive/normative moral language.
In pointing out dangers of thick moral words, I am not questioning their descriptive or evaluative content. Murder is a reality and it is a serious crime; the same is true of exploitation. I am just pointing out that the dual nature of thick moral words can turn our heads. Moral language can make us violent, dogmatic, righteous, and anxious about issues that perhaps exist mainly in our descriptions of reality.
I think most of us have fallen into such dark pits.
Posted by Pär Segerdahl 
