 Skepticism is generally any questioning attitude or doubt towards one or more items of putative knowledge or belief. 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. 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 urges 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. Basic skepticism concerns testing beliefs for reliability, by subjecting them to systematic investigation using the scientific method, to discover empirical evidence for them. In ordinary usage, skepticism U.S. or skepticism U.K. can refer to an attitude of doubt or a disposition to incredulity either in general or toward a particular object. The doctrine that true knowledge or some particular knowledge is uncertain, the method of suspended judgment, systematic doubt, or criticism that is characteristic of skeptics' Merriam-Webster. In philosophy, skepticism can refer to the mode of inquiry that emphasizes critical scrutiny, caution, and intellectual rigor, the method of obtaining knowledge through systematic doubt and continual testing, the set of claims about the limitations of human knowledge and the proper response to such limitations.