George Edward Moore was an English philosopher, who with Bertrand Russell, Ludwig Wittgenstein and earlier Gottlob Frege was among the initiators of analytic philosophy. He and Russell began deemphasizing the idealism which was then prevalent among British philosophers and became known for advocating common-sense concepts and contributing to ethics, epistemology and metaphysics. He was said to have an "exceptional personality and moral character". Ray Monk later dubbed him "the most revered philosopher of his era".
Sir Karl Raimund Popper was an Austrian–British philosopher, academic and social commentator. One of the 20th century's most influential philosophers of science, Popper is known for his rejection of the classical inductivist views on the scientific method in favour of empirical falsification. According to Popper, a theory in the empirical sciences can never be proven, but it can be falsified, meaning that it can be scrutinised with decisive experiments. Popper was opposed to the classical justificationist account of knowledge, which he replaced with critical rationalism, namely "the first non-justificational philosophy of criticism in the history of philosophy".
In logic, the law of non-contradiction (LNC) states that contradictory propositions cannot both be true in the same sense at the same time, e. g. the two propositions "p is the case" and "p is not the case" are mutually exclusive. Formally, this is expressed as the tautology ¬(p ∧ ¬p). The law is not to be confused with the law of excluded middle which states that at least one, "p is the case" or "p is not the case", holds.
In logic, the law of excluded middle states that for every proposition, either this proposition or its negation is true. It is one of the so-called three laws of thought, along with the law of noncontradiction, and the law of identity. However, no system of logic is built on just these laws, and none of these laws provides inference rules, such as modus ponens or De Morgan's laws.
The omnipotence paradox is a family of paradoxes that arise with some understandings of the term omnipotent. The paradox arises, for example, if one assumes that an omnipotent being has no limits and is capable of realizing any outcome, even a logically contradictory one such as creating a square circle. Atheological arguments based on the omnipotence paradox are sometimes described as evidence for countering theism. Other possible resolutions to the paradox hinge on the definition of omnipotence applied and the nature of God regarding this application and whether omnipotence is directed toward God Himself or outward toward his external surroundings.
First formulated by David Hume, the problem of induction questions our reasons for believing that the future will resemble the past, or more broadly it questions predictions about unobserved things based on previous observations. This inference from the observed to the unobserved is known as "inductive inferences". Hume, while acknowledging that everyone does and must make such inferences, argued that there is no non-circular way to justify them, thereby undermining one of the Enlightenment pillars of rationality.
The categorical imperative is the central philosophical concept in the deontological moral philosophy of Immanuel Kant. Introduced in Kant's 1785 Groundwork of the Metaphysics of Morals, it is a way of evaluating motivations for action. It is best known in its original formulation: "Act only according to that maxim whereby you can at the same time will that it should become a universal law."
Groundwork of the Metaphysics of Morals is the first of Immanuel Kant's mature works on moral philosophy and remains one of the most influential in the field. Kant conceives his investigation as a work of foundational ethics—one that clears the ground for future research by explaining the core concepts and principles of moral theory, and showing that they are normative for rational agents.
Critical rationalism is an epistemological philosophy advanced by Karl Popper on the basis that, if a statement cannot be logically deduced, it might nevertheless be possible to logically falsify it. Following Hume, Popper rejected any inductive logic that is ampliative, i.e., any logic that can provide more knowledge than deductive logic. This led Popper to his falsifiability criterion.
Kantianism is the philosophy of Immanuel Kant, a German philosopher born in Königsberg, Prussia. The term Kantianism or Kantian is sometimes also used to describe contemporary positions in philosophy of mind, epistemology, and ethics.
The Open Society and Its Enemies is a work on political philosophy by the philosopher Karl Popper, in which the author presents a "defence of the open society against its enemies", and offers a critique of theories of teleological historicism, according to which history unfolds inexorably according to universal laws. Popper indicts Plato, Hegel, and Marx for relying on historicism to underpin their political philosophies.
Ethical intuitionism is a view or family of views in moral epistemology. It is foundationalism applied to moral knowledge, the thesis that some moral truths can be known non-inferentially. Such an epistemological view is by definition committed to the existence of knowledge of moral truths; therefore, ethical intuitionism implies cognitivism.
The principle of sufficient reason states that everything must have a reason or a cause. The principle was articulated and made prominent by Gottfried Wilhelm Leibniz, with many antecedents, and was further used and developed by Arthur Schopenhauer and Sir William Hamilton, 9th Baronet.
The laws of thought are fundamental axiomatic rules upon which rational discourse itself is often considered to be based. The formulation and clarification of such rules have a long tradition in the history of philosophy and logic. Generally they are taken as laws that guide and underlie everyone's thinking, thoughts, expressions, discussions, etc. However, such classical ideas are often questioned or rejected in more recent developments, such as intuitionistic logic, dialetheism and fuzzy logic.
"Critique of the Kantian philosophy" is a criticism Arthur Schopenhauer appended to the first volume of his The World as Will and Representation (1818). He wanted to show Immanuel Kant's errors so that Kant's merits would be appreciated and his achievements furthered.
Originally, fallibilism is the philosophical principle that propositions can be accepted even though they cannot be conclusively proven or justified, or that neither knowledge nor belief is certain. The term was coined in the late nineteenth century by the American philosopher Charles Sanders Peirce, as a response to foundationalism. Theorists, following Austrian-British philosopher Karl Popper, may also refer to fallibilism as the notion that knowledge might turn out to be false. Furthermore, fallibilism is said to imply corrigibilism, the principle that propositions are open to revision. Fallibilism is often juxtaposed with infallibilism.
Physical causal closure is a metaphysical theory about the nature of causation in the physical realm with significant ramifications in the study of metaphysics and the mind. In a strongly stated version, physical causal closure says that "all physical states have pure physical causes" — Jaegwon Kim, or that "physical effects have only physical causes" — Agustin Vincente, p. 150.
Kantian ethics refers to a deontological ethical theory developed by German philosopher Immanuel Kant that is based on the notion that: "It is impossible to think of anything at all in the world, or indeed even beyond it, that could be considered good without limitation except a good will." The theory was developed in the context of Enlightenment rationalism. It states that an action can only be moral if (i) it is motivated by a sense of duty and (ii) its maxim may be rationally willed a universal, objective law.
British philosophy refers to the philosophical tradition of the British people. "The native characteristics of British philosophy are these: common sense, dislike of complication, a strong preference for the concrete over the abstract and a certain awkward honesty of method in which an occasional pearl of poetry is embedded".