Edmund Gustav Albrecht Husserl was an Austrian-German philosopher and mathematician who established the school of phenomenology.
Friedrich Ludwig Gottlob Frege was a German philosopher, logician, and mathematician. He was a mathematics professor at the University of Jena, and is understood by many to be the father of analytic philosophy, concentrating on the philosophy of language, logic, and mathematics. Though he was largely ignored during his lifetime, Giuseppe Peano (1858–1932), Bertrand Russell (1872–1970), and, to some extent, Ludwig Wittgenstein (1889–1951) introduced his work to later generations of philosophers. Frege is widely considered to be the greatest logician since Aristotle, and one of the most profound philosophers of mathematics ever.
Classical logic or Frege–Russell logic is the intensively studied and most widely used class of deductive logic. Classical logic has had much influence on analytic philosophy.
The history of logic deals with the study of the development of the science of valid inference (logic). Formal logics developed in ancient times in India, China, and Greece. Greek methods, particularly Aristotelian logic as found in the Organon, found wide application and acceptance in Western science and mathematics for millennia. The Stoics, especially Chrysippus, began the development of predicate logic.
Phenomenology is the philosophical study of objectivity and reality as subjectively lived and experienced. It seeks to investigate the universal features of consciousness while avoiding assumptions about the external world, aiming to describe phenomena as they appear to the subject, and to explore the meaning and significance of the lived experiences.
Franz Clemens Honoratus Hermann Josef Brentano was a German philosopher and psychologist. His 1874 Psychology from an Empirical Standpoint, considered his magnum opus, is credited with having reintroduced the medieval scholastic concept of intentionality into contemporary philosophy.
Analytic philosophy is a broad, contemporary movement or tradition within Western philosophy and especially anglophone philosophy focused on analysis.
Rudolf Hermann Lotze was a German philosopher and logician. He also had a medical degree and was well versed in biology. He argued that if the physical world is governed by mechanical laws and relations, then developments in the universe could be explained as the functioning of a world mind. His medical studies were pioneering works in scientific psychology.
Bernard Bolzano was a Bohemian mathematician, logician, philosopher, theologian and Catholic priest of Italian extraction, also known for his liberal views.
Alexius Meinong Ritter von Handschuchsheim was an Austrian philosopher, a realist known for his unique ontology. He also made contributions to philosophy of mind and theory of value.
Friedrich Wilhelm Karl Ernst Schröder was a German mathematician mainly known for his work on algebraic logic. He is a major figure in the history of mathematical logic, by virtue of summarizing and extending the work of George Boole, Augustus De Morgan, Hugh MacColl, and especially Charles Peirce. He is best known for his monumental Vorlesungen über die Algebra der Logik, in three volumes, which prepared the way for the emergence of mathematical logic as a separate discipline in the twentieth century by systematizing the various systems of formal logic of the day.
Kazimierz Jerzy Skrzypna-Twardowski was a Polish philosopher, psychologist, logician, and rector of the Lwów University. He was initially affiliated with Alexius Meinong's Graz School of object theory.
Philosophical realism – usually not treated as a position of its own but as a stance towards other subject matters – is the view that a certain kind of thing has mind-independent existence, i.e. that it exists even in the absence of any mind perceiving it or that its existence is not just a mere appearance in the eye of the beholder. This includes a number of positions within epistemology and metaphysics which express that a given thing instead exists independently of knowledge, thought, or understanding. This can apply to items such as the physical world, the past and future, other minds, and the self, though may also apply less directly to things such as universals, mathematical truths, moral truths, and thought itself. However, realism may also include various positions which instead reject metaphysical treatments of reality entirely.
Munich phenomenology is the philosophical orientation of a group of philosophers and psychologists that studied and worked in Munich at the turn of the twentieth century. Their views are grouped under the names realistphenomenology or phenomenology of essences. Munich phenomenology represents one branch of what is referred to as the early phenomenology. One of their contributions was the theory that there are different kinds of intentionality.
Psychologism is a family of philosophical positions, according to which certain psychological facts, laws, or entities play a central role in grounding or explaining certain non-psychological facts, laws, or entities. The word was coined by Johann Eduard Erdmann as Psychologismus, being translated into English as psychologism.
Philosophy of Arithmetic: Psychological and Logical Investigations is an 1891 book about the philosophy of mathematics by the philosopher Edmund Husserl. Husserl's first published book, it is a synthesis of his studies in mathematics, under Karl Weierstrass, with his studies in philosophy and psychology, under Franz Brentano, to whom it is dedicated, and Carl Stumpf.
In mathematical logic, algebraic logic is the reasoning obtained by manipulating equations with free variables.
Philosophy of logic is the area of philosophy that studies the scope and nature of logic. It investigates the philosophical problems raised by logic, such as the presuppositions often implicitly at work in theories of logic and in their application. This involves questions about how logic is to be defined and how different logical systems are connected to each other. It includes the study of the nature of the fundamental concepts used by logic and the relation of logic to other disciplines. According to a common characterisation, philosophical logic is the part of the philosophy of logic that studies the application of logical methods to philosophical problems, often in the form of extended logical systems like modal logic. But other theorists draw the distinction between the philosophy of logic and philosophical logic differently or not at all. Metalogic is closely related to the philosophy of logic as the discipline investigating the properties of formal logical systems, like consistency and completeness.
The Logical Investigations is a two-volume work by the philosopher Edmund Husserl, in which the author discusses the philosophy of logic and criticizes psychologism, the view that logic is based on psychology.
Early phenomenology refers to the early phase of the phenomenological movement, from the 1890s until the Second World War. The figures associated with the early phenomenology are Edmund Husserl and his followers and students, particularly the members of the Göttingen and Munich Circles, as well as a number of other students of Carl Stumpf and Theodor Lipps, and excludes the later existential phenomenology inspired by Martin Heidegger. Early phenomenology can be divided into two theoretical camps: realist phenomenology, and transcendental or constitutive phenomenology.