seldom dealt explicitly with his materials. In her earlier career, Foot's works were meta-ethical in character, pertaining to the nature and status of moral judgment and language. Her essays "Moral Arguments" and "Moral Beliefs" were significant in dethroning non-cognitivism as the dominant meta-ethical theory of preceding decades. Though non-cognitivism may be traced back to Hume's Is–ought problem, its most explicit formulations are found in the works of A. J. Ayer, C. L. Stevenson, and R. M. Hare, who focused on abstract or "thin" ethical concepts such as good/bad and right/wrong. They argued that moral judgments do not express propositions, i.e., that they are not truth-apt, but express emotions or imperatives. Thus, fact and value are independent of each other. This analysis of abstract or "thin" ethical concepts was contrasted with more concrete or "thick" concepts, such as cowardice, cruelty, and gluttony. Such attributes do not swing free of the facts, yet they carry the same "practicality" that "bad" or "wrong" do. They were intended to combine the particular, non-cognitive "evaluative" element championed by the theory with the descriptive element. One could detach the evaluative force by employing them in an "inverted commas sense", as one does in attempting to articulate thoughts in a system one opposes, for example by putting "unmanly" or "unladylike" in quotation marks. That leaves purely descriptive expressions that apply to actions, whereas employing such expressions without the quotation marks would add the non-cognitive extra of "and such action is bad". Foot objected to this distinction and its underlying account of thin concepts. Her defense of the cognitive and truth-evaluable character of moral judgment made the essays crucial in bringing the question of the rationality of morality to the fore. Practical considerations involving "thick" ethical concepts – "but it would be cruel", "it would be cowardly", "it's for her to do", or "I promised her I wouldn't do it" – move people to act one way rather than another, but remain as purely descriptive as any other judgment pertaining to human life. They differ from thoughts such as "it would be done on a Tuesday" or "it would take about three gallons of paint" not by admixing what she considers a non-factual, attitude-expressing, "moral" element, but simply by the fact that people have reason not to do things that are cowardly or cruel. Her lifelong devotion to the question is apparent in all periods of her work.