Judgments of Value and Propositions of Existence
PROPOSITIONS asserting existence (affirmative existential propositions) or nonexistence (negative existential propositions) are descriptive. They assert something about the state of the whole universe or of parts of the universe. With regard to them questions of truth and falsity are significant. They must not be confounded with judgments of value. Judgments of value are voluntaristic. They express feelings, tastes, or preferences of the individual who utters them. With regard to them there cannot be any question of truth and falsity. They are ultimate and not subject to any proof or evidence. Judgments of value are mental acts of the individual concerned. As such they must be sharply distinguished from the sentences by means of which an individual tries to inform other people about the content of his judgments of value. A man may have some reason to lie about his valuations. We may describe this state of affairs in the following way: Every judgment of value is in itself also a fact of the actual state of the universe and as such may be the topic of existential propositions. The sentence “I prefer Beethoven to Lehar” refers to a judgment of value. If looked upon as an existential proposition, it is true if I really prefer Beethoven and act accordingly and false if I in fact prefer Lehar and for some reasons lie about my real feelings, taste, or preferences. In an analogous way the existential proposition “Paul prefers Beethoven to Lehar” may be true or false. In declaring that with regard to a judgment of value there cannot be any question of truth or falsity, we refer to the judgment as such and not to the sentences communicating the content of such a judgment of value to other people.
THEORY AND HISTORY, pp. 19-20, Ludwig von Mises