It may seem that there is a big difference between concepts such as the concepts of something, of logical consequence and of disjunction, on the one hand, and concepts such as the concepts of yellow, of emotion or of inflation, on the other hand. Attempts to specify or understand the difference between (some) formal or logical concepts (properties, objects, expressions) and non-formal or non-logical concepts (properties, objects, expressions) loom large in Austrian philosophy. Bolzano, Husserl and Wittgenstein all took the project seriously.