Empirical or a posteriori knowledge is propositional knowledge obtained by experience or sensorial information. It is contrasted with a priori knowledge, or knowledge that is gained through the apprehension of innate ideas, "intuition," "pure reason," or other non-experiential sources. Propositional knowledge or declarative knowledge is knowledge that some proposition is either true or false. ... A priori is a Latin phrase meaning from the former or less literally before experience. In much of the modern Western tradition, the term a priori is considered to mean propositional knowledge that can be had without, or prior to, experience. ... In philosophy and psychology, an innate idea is a concept or item of knowledge which is said to be universal to all humanity — that is, something people are born with rather than something people have learned through experience. ... Intuition has many but close meanings across many cultures, including: Quick and ready insight seemingly independent of previous experiences and empirical knowledge Immediate apprehension or cognition Knowledge or conviction gained immediately and without detailed consideration The power or faculty of attaining knowledge or cognition immediately without thought and inference. ... Reason is a term used in philosophy and other human sciences to refer to the higher cognitive faculties of the human mind. ...

The natural and social sciences are usually considered a posteriori, literally "after the fact," disciplines. Mathematics and logic are usually considered a priori, "before the fact," disciplines. The lunar farside as seen from Apollo 11 Natural science is the study of the physical, nonhuman aspects of the Earth and the universe around us. ... Terms like SOSE (Studies of Society & the Environment) not only refer to social sciences but also studies of the environment. ... Empirical or a posteriori knowledge is propositional knowledge obtained by experience. ... Euclid, detail from The School of Athens by Raphael. ... Logic, from Classical Greek λόγος (logos), originally meaning the word, or what is spoken, (but coming to mean thought or reason) is most often said to be the study of criteria for the evaluation of arguments, although the exact definition of logic is a matter of controversy among philosophers. ... A priori is a Latin phrase meaning from the former or less literally before experience. In much of the modern Western tradition, the term a priori is considered to mean propositional knowledge that can be had without, or prior to, experience. ...

For example, "all things fall down" would be an empirical proposition about gravity that many of us believe we know; therefore we would regard it as an example of empirical knowledge. It is "empirical" because we have generally observed that things fall down, so there is no reason to believe this will change. This example also shows the difficulty of formulating knowledge claims. Outside of the Earth's gravitational field, for example, things do not "fall down", as there is no "down". Gravity is a force of attraction that acts between bodies that have mass. ... Empirical is an adjective often used in conjunction with science, both the natural and social sciences, which means an observation or experiment based upon experience that is capable of being verified or disproved. ... Earth is the third planet in the Solar system. ...

The vast bulk of the empirical knowledge that ordinary people possess is gained via a mixture of direct experience and the testimony of others about what they have experienced—iterated in an interesting way that is studied in the field of social epistemology as well as other fields. More complicated and organized methods of gaining empirical knowledge are the methods of science—see scientific method—which result in perhaps the best examples of rigorously codified, scientific empirical knowledge, namely, physics. In philosophy, testimony includes any words or utterances that are presented as evidence for the claims they express. ... Social epistemology can be split into two broad camps: the radical and the non-radical. ... The scope of this article is limited to the empirical sciences. ... Scientific method refers to a body of techniques for the investigation of phenomena and the acquisition of new knowledge of the natural world, as well as the correction and integration of previous knowledge, based on observable, empirical, measurable evidence, and subject to laws of reasoning. ... A Superconductor demonstrating the Meissner Effect. ...

David Hume considered all a posteriori knowledge to be a Matter of Fact, and never explicitly utilised the term. David Hume (April 26, 1711 – August 25, 1776)[1] was a Scottish philosopher, economist, and historian who was one of the most important figures of the Scottish Enlightenment. ... A Matter of Fact, in the Humean sense, is the type of knowledge that can be characterized as arising out of ones interaction with and experience in the external world (as compared to a Relation of Ideas). ...

The modern perusal of a posteriori thought began with Immanuel Kant in a reactionary movement to Hume's sceptical approach to knowledge in his Enquiry Concerning Human Understanding. Kant, in adding the distinction between synthetic and analytic truths to the distinction between a priori and a posteriori knowledge, created four categories of knowledge (one of which, the analytic a posteriori, is never possible). Thus, for Kant, the only type of a posteriori knowledge is the synthetic a posteriori. Because of this, Kant proposes that a posteriori propositions are, as a set, contingent, because a posteriori propositions all depend on external conditions, which may change in time, making the proposition false (e.g. "My dog is a puppy" has a truth value only ascertained by external verification). Immanuel Kant (22 April 1724 – 12 February 1804), was a German philosopher from Königsberg (now Kaliningrad) in East Prussia. ... An Enquiry Concerning Human Understanding is a book by philosopher David Hume, published in 1748. ... Analytic may refer to Analytic proposition or analytic philosophy, in philosophy Analytic geometry, analytic function, analytic continuation, analytic set in mathematics. ... Empirical or a posteriori knowledge is propositional knowledge obtained by experience. ... Generally, synthetic means pertaining to synthesis, i. ...

Saul Kripke contends that the category of analytic a posteriori truths is nonempty, including, among other things, identity claims such as "Water is H₂O" and "Hesperus is Phosphorus." Saul Aaron Kripke (born in November, 1940, Omaha, Nebraska) is an American philosopher and logician now emeritus from Princeton and professor of philosophy at CUNY Graduate Center. ...

See also

• A priori
• Empiricism
• Epistemology