Last night, I was reading the introduction to Economic Science and the Austrian Method, by Hans-Hermann Hoppe, an adherent of the Austrian school. In the introduction, the author argues that economics is fundamentally an a priori science, rather than an empirical one, an intriguing proposition that encourages me to read on.
Proposition: a proposition is a statement that can come after phrases such as “I believe that”, “I know that”, etc. “The sky is blue” is a proposition. The complexity of language allows propositions to be expressed in a variety of ways. For the purpose of analysis and investigation, it is often desirable to convert other forms into an “X is Y” format before proceeding.
Subject: “The sky is blue”. In the proposition, “The sky is blue”, “The sky” is the subject of the proposition.
Predicate: “The sky is blue”; in this proposition, the predicate – i.e. the thing asserted of the subject – is “blue”.
Copula: The copula is the part of the proposition that joins the subject to the predicate, usually some form of the verb “to be”. In “The sky is blue”, the copula is “is”.
Analytic: A proposition is classed as analytic if it is true by definition (by virtue of the meanings of words and the rules of language). “A bachelor is an unmarried man” is an analytic proposition. While this proposition is easy to understand and verify, it does not follow that all analytic propositions are so easy to grasp. Many are very complex.
Synthetic: A proposition is classed as synthetic if is true by virtue of how the world is. “Most species of tomato, when ripe, are red” is a synthetic proposition. It is not true that tomatoes are red by definition. It is possible to imagine a universe in which there are tomatoes in a variety of colours (as indeed there exist ripe yellow tomatoes in our universe).
A priori: A proposition whose truth can be determined by reason alone, without reference to data obtained from the senses, is said to be known a priori (because this is a Latin phrase, the convention is to italicize it when used in other languages such as English).
A posteriori: A proposition whose truth can be determined only by reference to data obtained via the senses is said to be known a posteriori.
Knowledge empiricism: knowledge empiricism holds that the truth of all synthetic propositions can be known only a posteriori. All a priori knowledge is confined to analytic propositions.
Knowledge rationalism: knowledge rationalism holds that there is a class or classes of synthetic propositions that can be known a priori – by reason alone.
Empirical science: empirical branches of science require sensory data to determine the truth of propositions whose investigation properly lies within their domains.
A priori science: a priori branches of science rely on reason alone to determine the truth of the propositions whose investigation properly lies within their domains.