Croce says that: "Of those three forms of logical scepticism, aestheticism, mysticism, and empiricism, the third one leads us to the distinction between the logical concept and the scientific concepts, or fictions." He explains this in Logic as the science of the pure concept , which was translated by Douglas Ainslie in 1917, in this manner:
'[Concepts like cat or rose] ... can be looked upon as something fixed and precise, only when we have regard to some particular group of cats and of roses, indeed to one particular cat or rose at a definite moment of its existence (a gray cat or a black cat, a cat or a kitten; a white rose or a red rose, flowering or withered, etc.), elevated into a symbol and representative of the others. There is not, and there cannot be, a rigorous characteristic, which should avail to distinguish the cat from other animals, or the rose from other flowers, or indeed a cat from other cats and a rose from another rose. These and other fictional concepts are, therefore, representative, but not ultrarepresentative; they contain some objects or fragments of reality, they do not contain it all.
'[On the other hand] The conceptual fictions of the triangle and of...universals, ... have an analogous but opposite representations defect. With them, it appears, we emerge from the difficulties of representations. The triangle and free motion are not something which begins and ends in time and of which we are not able to state exactly the character and limits. So long as thought, that is to say, thinkable reality, exists, the concept of the triangle ...will have validity.'
By placing scientific concepts among the category he calls fictional concepts (like cat) , Croce thought he had diminished the imperialism of positivism. His defense of philosophy is matched by his physical bravery during the fascist era.