Philosophy, for Ortega, is that activity in which some of us engage when we seek intellectual security. Its task is to provide us with the unconditional which lies behind the conditional. The philosopher is faced with the challenge of discovering that reality on which all others depend – what Ortega calls radical reality, or realidad radical.

In ¿Qué es filosofía? and ¿Qué es conocimiento?, he sets out two conditions that such a principle must fulfill if it is to be truly radical: it must be ‘ultimate and integral’, or, as he also puts it, ‘autonomous and pantonomous’. Thus: ‘A truth is ultimate when it does not refer back to or presuppose another. It is integral when it is absolutely true with reference to all other truths, and this is only possible if all other truths refer back to it or presuppose it’ (QC, 27). And, ‘Because of its unlimited range and the radical problematic of its subject, philosophical thought has to comply with two laws or obligations. It has to be autonomous, in the sense of not admitting any truth which it itself has not generated; and it has to be pantonomous, in the sense of not being definitively content with any position which does not express universal values, or which does not, in other words, aim at the Universe’ (OC 7, 349). Finally, ‘Philosophy is a science without presuppositions.