Wolfgang Lenzen
Biographic Data
| ID | 6233763 |
|---|---|
| NAME | Wolfgang Lenzen |
| GIVEN NAMES | Wolfgang |
| FAMILY NAME | Lenzen |
| SIGNATURE | LENZEN W |
| AFFILIATIONS | Department of Philosophy, University of Osnabrück, Osnabrück, Germany |
| ORCID | 0000-0002-5456-1685 |
| VERIFIED | Yes |
| TOTAL WORKS | 14 |
| TOTAL CITATIONS | 0 |
| WORKS AS AUTHOR | 12 |
| WORKS AS EDITOR | 2 |
| FIRST PUBLICATION YEAR | 1990 |
| LATEST PUBLICATION YEAR | 2026 |
| H-INDEX | 0 |
A Medieval Controversy about Entailments between Categorical and ‘Continuing’ Propositions
The early thirteenth century tract Ars Meliduna deals with the issue whether categorical propositions entail, or are entailed by, ‘continuing’ propositions, i.e. by implications. From the perspective of modern logic, with implication interpreted as a material, truth-functional connective, the first question has to be answered in the affirmative because, e.g. β entails (α ⊃ β). But conversely (α ⊃ β) ‘normally’ doesn’t entail the truth (or the fal…
Buridan’s Theory of Consequences
Buridan endorses the basic idea that q follows from p iff it is impossible that p is true but q is false. Since he also accepts the law that, if p is impossible, the conjunction (p ∧ q) must be impossible, he comes to regard the principle ‘Ex impossibili quodlibet’ (EIQ) as basically correct. However, his logic is based on a ‘nominalist’ view according to which propositions are tokens of spoken, written or thought language existing in space of ti…
Buridan on ‘Ex impossibili quodlibet’, ‘Ex contradictione quodlibet’, and ‘Ex falso quodlibet’
Buridan endorsed the principles that any impossible, and a fortiori any self-contradictory, proposition entails each proposition. These principles are usually referred to as ‘Ex impossibili quodlibet’ (EIQ) and ‘Ex contradictione quodlibet’ (ECQ). Buridan further considered the instance ECCQ according to which any proposition follows from the conjunction of two contradictory propositions. Buridan showed how ECCQ can be proven by means the usual l…
What Follows from the Impossible
One of the main controversies of the Logic Schools of the 12th century centered on the question: What follows from the impossible? In this paper arguments for two diametrically opposed positions are examined. The author of the ‘Avranches Text’ who probably belonged to the school of the Parvipontani defended the view that from an impossible proposition everything follows (‘Ex impossibili quodlibet’). In particular he developed a proof to show that…
A Critical Examination of the Historical Origins of Connexive Logic
It is often assumed that Aristotle, Boethius, Chrysippus, and other ancient logicians advocated a connexive conception of implication according to which no proposition entails, or is entailed by, its own negation. Thus Aristotle claimed that the proposition ‘if B is not great, B itself is great [...] is impossible’. Similarly, Boethius maintained that two implications of the type ‘If p then r’ and ‘If p then not-r’ are incompatible. Furthermore, …
Schriften zur Syllogistik
Leibniz's laws of consistency and the philosophical foundations of connexive logic
As an extension of the traditional theory of the syllogism, Leibniz’s algebra of concepts is built up from the term-logical operators of conjunction, negation, and the relation of containment.Leibniz’s laws of consistency state that no concept contains its own negation, and that if concept A contains concept B, then A cannot also contain Not-B. Leibniz believed that these principles would be universally valid, but he eventually discovered that th…
Ist Folter erlaubt?
Das Buch erörtert mit Blick auf den "Fall Daschner" sowie auf theoretische, bislang zum Glück fiktiv gebliebene Tickende-Bombe-Szenarien die ethischen und juristischen Aspekte der Folter-Problematik. Im Falle Daschner ging es nicht um die Androhung echter Folter, sondern allenfalls um Folter-in-Anführungszeichen, d.h. um unmittelbaren Zwang im Sinne des Polizei- bzw. Gefahrenabwehrrechts. Eine solche Unterscheidung zwischen Folter und 'Folter' is…
Auf der Suche nach dem verlorenen »Selbst« — Thomas Metzinger und die »letzte Kränkung« der Menschheit
Alles nur Illusionen? - Philosophische (In-)Konsequenzen der Neurobiologie
Searles verpatzte Lösung des Freiheitsproblems
Searles verpatzte Lösung des Freiheitsproblems
Damasios Theorie der Emotionen
Das Töten von Tieren und von Föten
Singer’s ‘Practical Ethics’ is based on a form of utilitarianism which takes into account the interests of a living being if and only if it displays a minimum of rationality and (self-)consciousness. Accordingly aborting a human fetus in an early stage of development is held to be morally acceptable, whereas killing chicken, pigs, and cattle for mere culinary pleasure is not. Singer's view on abortion are refuted because they only consider the ac…
No prominent works on this page.
Das Töten von Tieren und von Föten
Singer’s ‘Practical Ethics’ is based on a form of utilitarianism which takes into account the interests of a living being if and only if it displays a minimum of rationality and (self-)consciousness. Accordingly aborting a human fetus in an early stage of development is held to be morally acceptable, whereas killing chicken, pigs, and cattle for mere culinary pleasure is not. Singer's view on abortion are refuted because they only consider the ac…
Damasios Theorie der Emotionen
Alles nur Illusionen? - Philosophische (In-)Konsequenzen der Neurobiologie
Searles verpatzte Lösung des Freiheitsproblems
Searles verpatzte Lösung des Freiheitsproblems
Ist Folter erlaubt?
Das Buch erörtert mit Blick auf den "Fall Daschner" sowie auf theoretische, bislang zum Glück fiktiv gebliebene Tickende-Bombe-Szenarien die ethischen und juristischen Aspekte der Folter-Problematik. Im Falle Daschner ging es nicht um die Androhung echter Folter, sondern allenfalls um Folter-in-Anführungszeichen, d.h. um unmittelbaren Zwang im Sinne des Polizei- bzw. Gefahrenabwehrrechts. Eine solche Unterscheidung zwischen Folter und 'Folter' is…
Auf der Suche nach dem verlorenen »Selbst« — Thomas Metzinger und die »letzte Kränkung« der Menschheit
Schriften zur Syllogistik
Leibniz's laws of consistency and the philosophical foundations of connexive logic
As an extension of the traditional theory of the syllogism, Leibniz’s algebra of concepts is built up from the term-logical operators of conjunction, negation, and the relation of containment.Leibniz’s laws of consistency state that no concept contains its own negation, and that if concept A contains concept B, then A cannot also contain Not-B. Leibniz believed that these principles would be universally valid, but he eventually discovered that th…
A Critical Examination of the Historical Origins of Connexive Logic
It is often assumed that Aristotle, Boethius, Chrysippus, and other ancient logicians advocated a connexive conception of implication according to which no proposition entails, or is entailed by, its own negation. Thus Aristotle claimed that the proposition ‘if B is not great, B itself is great [...] is impossible’. Similarly, Boethius maintained that two implications of the type ‘If p then r’ and ‘If p then not-r’ are incompatible. Furthermore, …
What Follows from the Impossible
One of the main controversies of the Logic Schools of the 12th century centered on the question: What follows from the impossible? In this paper arguments for two diametrically opposed positions are examined. The author of the ‘Avranches Text’ who probably belonged to the school of the Parvipontani defended the view that from an impossible proposition everything follows (‘Ex impossibili quodlibet’). In particular he developed a proof to show that…
Buridan on ‘Ex impossibili quodlibet’, ‘Ex contradictione quodlibet’, and ‘Ex falso quodlibet’
Buridan endorsed the principles that any impossible, and a fortiori any self-contradictory, proposition entails each proposition. These principles are usually referred to as ‘Ex impossibili quodlibet’ (EIQ) and ‘Ex contradictione quodlibet’ (ECQ). Buridan further considered the instance ECCQ according to which any proposition follows from the conjunction of two contradictory propositions. Buridan showed how ECCQ can be proven by means the usual l…
Buridan’s Theory of Consequences
Buridan endorses the basic idea that q follows from p iff it is impossible that p is true but q is false. Since he also accepts the law that, if p is impossible, the conjunction (p ∧ q) must be impossible, he comes to regard the principle ‘Ex impossibili quodlibet’ (EIQ) as basically correct. However, his logic is based on a ‘nominalist’ view according to which propositions are tokens of spoken, written or thought language existing in space of ti…
A Medieval Controversy about Entailments between Categorical and ‘Continuing’ Propositions
The early thirteenth century tract Ars Meliduna deals with the issue whether categorical propositions entail, or are entailed by, ‘continuing’ propositions, i.e. by implications. From the perspective of modern logic, with implication interpreted as a material, truth-functional connective, the first question has to be answered in the affirmative because, e.g. β entails (α ⊃ β). But conversely (α ⊃ β) ‘normally’ doesn’t entail the truth (or the fal…
Philosophy (11 works) · Classical Philosophy and Thought (6 works) · Epistemology (5 works) · Medieval and Classical Philosophy (5 works) · Linguistics (3 works) · Mathematics (3 works) · Political science (3 works) · Psychology (3 works) · Criminal Law and Policy (2 works) · Discrete mathematics (2 works)