The fact-value distinction is literally as the term suggests, an attempt to distinguish between a fact and a value. We must understand what facts are and what values are. Facts are anything that renders a proposition to be either true or false, be it a statement about an object, e.g. a car is a mode of transportation or comparison, a cat is smaller in size than a giraffe. A value, on the other hand, is based on an evaluative judgment, it is more subjective than stating a fact and thus differs from person to person. When we make statements such as lying is bad or respecting your elders is good.
One distinction that is made between the fact and value is based on the language that is used while making statements that are fact versus while making evaluative statements. The facts are often judged by whether they are true or false, the values, on the other hand, are often judged by terms such as good, bad, right or wrong, etc. We find that when we form sentences, they maybe be descriptive and thus describing a fact, like a sky is blue, or they may be based on perspective, which has been advocated by the emotivists such as C.L. Stevenson, sentences such as stealing is bad. Unlike descriptive sentences, these are more focused on expressing the feelings and attitudes of the individual making the judgment.
Another important argument for this distinction can be seen in the case of logical positivism, which was a part of philosophy and advocated for the belief that philosophy must use the same method as science and base its judgment about things on whether they are true or false. Logical positivism adopted what was known as the principle of verification. This made a distinction between the fact and value based on whether the statement could be empirically backed or not, thus anything that one can find empirical evidence for is a fact e.g. an apple is red is a fact as it can be verified. However, stealing is wrong becomes a value as it cannot be verified empirically. Thus emotivism and prescriptivism are of the belief that these values are actually people’s attitudes and ways of expressing.
David Hume provided one more important argument for this distinction, this was the is-ought problem also known as Hume’s Law, this problem is related to the idea that one cannot derive statements about what ‘ought’ to be from what ‘is’. There was a clear distinction between a normative/prescriptive, which was what ought to be, and positive statements, which was what is. However, an ought statement may be converted into what is. For example, one ought to not steal can be converted into, stealing is a crime. Thus from Hume’s law, we are able to uphold the fact-value distinction.
There also tends to be a relation between the error theory and the distinction. The error theory is based on two propositions; one is that all moral claims are false and second that there is a reason to believe that they are false. Thus stating that there are no objective values. And thus there exists a distinction between what is a fact and value.