
Scharp on Replacing Truth
... Leibniz’s law we can infer that L is true if and only if it isn’t. If we furthermore assume the classical laws of logic we can derive from this any conclusion we like. Something has clearly gone wrong somewhere. But saying where it went wrong is only half the problem. It is surely also important tha ...
... Leibniz’s law we can infer that L is true if and only if it isn’t. If we furthermore assume the classical laws of logic we can derive from this any conclusion we like. Something has clearly gone wrong somewhere. But saying where it went wrong is only half the problem. It is surely also important tha ...
Chapter 2, Logic
... What is Philosophy Chapter 2 by Richard Thompson gave rise to a good deal of debate among logicians. For sometimes we assert universal generalisations without any commitment to existence. For instance if we explained ‘unicorn’ by saying ‘Unicorn’ means ’quadruped mammal resembling a horse but with ...
... What is Philosophy Chapter 2 by Richard Thompson gave rise to a good deal of debate among logicians. For sometimes we assert universal generalisations without any commitment to existence. For instance if we explained ‘unicorn’ by saying ‘Unicorn’ means ’quadruped mammal resembling a horse but with ...
Document
... • Questions: Are there infinitely many of these primitive ones? Can we figure out a way to manufacture them? ...
... • Questions: Are there infinitely many of these primitive ones? Can we figure out a way to manufacture them? ...
Interpreting Lattice-Valued Set Theory in Fuzzy Set Theory
... well as its predecessor [14], builds upon results of set theory in intuitionistic logic, as given by W. C. Powell [12] and R. J. Grayson [7], which is apparent, among other things, in its spelling of axioms—in a weak setting (such as that of an intermediate logic), different but classically equivale ...
... well as its predecessor [14], builds upon results of set theory in intuitionistic logic, as given by W. C. Powell [12] and R. J. Grayson [7], which is apparent, among other things, in its spelling of axioms—in a weak setting (such as that of an intermediate logic), different but classically equivale ...
Principia Mathematica

The Principia Mathematica is a three-volume work on the foundations of mathematics, written by Alfred North Whitehead and Bertrand Russell and published in 1910, 1912, and 1913. In 1927, it appeared in a second edition with an important Introduction To the Second Edition, an Appendix A that replaced ✸9 and an all-new Appendix C.PM, as it is often abbreviated, was an attempt to describe a set of axioms and inference rules in symbolic logic from which all mathematical truths could in principle be proven. As such, this ambitious project is of great importance in the history of mathematics and philosophy, being one of the foremost products of the belief that such an undertaking may be achievable. However, in 1931, Gödel's incompleteness theorem proved definitively that PM, and in fact any other attempt, could never achieve this lofty goal; that is, for any set of axioms and inference rules proposed to encapsulate mathematics, either the system must be inconsistent, or there must in fact be some truths of mathematics which could not be deduced from them.One of the main inspirations and motivations for PM was the earlier work of Gottlob Frege on logic, which Russell discovered allowed for the construction of paradoxical sets. PM sought to avoid this problem by ruling out the unrestricted creation of arbitrary sets. This was achieved by replacing the notion of a general set with the notion of a hierarchy of sets of different 'types', a set of a certain type only allowed to contain sets of strictly lower types. Contemporary mathematics, however, avoids paradoxes such as Russell's in less unwieldy ways, such as the system of Zermelo–Fraenkel set theory.PM is not to be confused with Russell's 1903 Principles of Mathematics. PM states: ""The present work was originally intended by us to be comprised in a second volume of Principles of Mathematics... But as we advanced, it became increasingly evident that the subject is a very much larger one than we had supposed; moreover on many fundamental questions which had been left obscure and doubtful in the former work, we have now arrived at what we believe to be satisfactory solutions.""The Modern Library placed it 23rd in a list of the top 100 English-language nonfiction books of the twentieth century.