Skepticism (American English) or scepticism (British English, Australian English) is generally any questioning attitude or doubt towards one or more items of putative knowledge or belief.12 It is often directed at domains, such as the supernatural, morality (moral skepticism), religion (skepticism about the existence of God), or knowledge (skepticism about the possibility of knowledge, or of certainty).3 Formally, skepticism as a topic occurs in the context of philosophy, particularly epistemology, although it can be applied to any topic such as politics, religion, and pseudoscience.
Philosophical skepticism comes in various forms. Radical forms of skepticism deny that knowledge or rational belief is possible and urge us to suspend judgment on many or all controversial matters. More moderate forms of skepticism claim only that nothing can be known with certainty, or that we can know little or nothing about the “big questions” in life, such as whether God exists or whether there is an afterlife. Religious skepticism is “doubt concerning basic religious principles (such as immortality, providence, and revelation)”.4 Scientific skepticism concerns testing beliefs for reliability, by subjecting them to systematic investigation using the scientific method, to discover empirical evidence for them.