In recent and contemporary philosophy.

Irrational Skepticism was developed into Existentialism by Soren

Kierkegaard in the 19th century. Using traditional Skeptical themes to attack Hegelianism and liberal Christianity, Kierkegaard stressed the need for faith. Only by an unjustified and unjustifiable "leap into faith" could certainty be found--which woul d then be entirely subjective rather than objective. Modern neo-orthodox and Existentialist theologians have argued that Skepticism highlights man's inability to find any ultimate truth except through faith and commitment. Nonreligious forms of this view have been developed by Existentialist writers like Albert Camus, combining the epistemological Skepticism of Kierkegaard with the religious and value Skepticism of Nietzsche. The rational and scientific examination of the world shows it to be unintellig ible and absurd; and if God is dead, as Nietzsche proclaimed, then the world is ultimately meaningless. But it is necessary to struggle with it. It is thus through action and commitment that one finds whatever personal meaning one can, though it has no ob jective

significance.

Other kinds of Skepticism appear in various forms of recent and

contemporary philosophy. The English Idealist F.H. Bradley used classical Skeptical arguments in his Appearance and

Reality: A Metaphysical Essay to contend that the world could not be understood empirically or materialistically; true knowledge could be

reached only by transcending the world of appearance.

George Santayana, an American critical Realist, in Scepticism and

Animal Faith, presented a naturalistic Skepticism. Any interpretation of immediate or intuited experience is open to question. To make life

meaningful, however, men make interpretations by "animal faith,"

according to biological and social factors. The resulting beliefs, though unjustified and perhaps illusory, enable them to persevere and find the richness of life.

Types of Skepticism also appear in Logical Positivism (see below

Positivism and Logical Empiricism) and various forms of linguistic philosophy (see below Analytic and Linguistic Philosophy). The attack

on speculative metaphysics developed by the physicist and early

Positivist Ernst Mach, by Bertrand Russell, and by Rudolf Carnap, a leader in the Vienna Circle, where Logical Positivism was nourished,

incorporated a Skepticism about the possibility of gaining knowledge

beyond experience or logical tautologies. Russell and the important philosopher of science Karl Popper have further stressed the unjustifiability of the principle of induction, and Popper has criticized theories of knowledge based upon empirical verif ication. A founder of linguistic analysis, Fritz Mauthner, has set forth a Skepticism in which any language is merely relative to its users and thus subjective. Every attempt to tell what is true just leads one back to linguistic formulations, not to obje ctive states of reality.