The claim that moral values cannot be derived from facts concerns the distinction between facts and values and the difference between what is and what ought to be.
There are those who argue that the claim is false, such as naturalists, who argue that there are indeed natural facts thus suggesting that moral values can be indentified as possessing empirical properties. Naturalists suggest that moral truths can be derived from facts about human behaviour for example, “it is a fact that suffering evokes human sympathy” thus making it a form of moral realism which states that there exists an ethical reality and just as there is an atomic structure to the world, there is also a singular moral structure to events in the world which local variations reflect. For example, psychological egoism states that people cannot help but act in their own self-interest and the moral perception of “good” is whatever people perceive to be in their own self-interest. Therefore, naturalists would argue that the moral value of “good” can be derived from our self-interest which is a fact about human nature. Using this example the claim that moral values cannot be derived from facts is false.
Moore attacks the naturalist perception of moral values, particularly in the naturalist definition of “good”. He argues that the word “good” is indefinable and is explained in his “open question argument”. This argument suggests that any definition should result in a closed question. For example, a bachelor is defined as an unmarried man therefore making it a closed question to ask whether a certain bachelor is unmarried, as the answer would only and always be yes. This question is a tautology and therefore a closed question. The same cannot be said of the proposition “all bachelors are ugly” because it leads to an open question, since the answer could be yes or no. this is because the meaning of ugly is not contained within