This book traces the development of formal logic from its origins inancient Greece to the present day. The authors first discuss the work oflogicians from Aristotle to Frege, showing how they were influenced by thephilosophical or mathematical ideas of their time. They then examinedevelopments in the present century.
The author criticizes pear's use of the notion of material implication in his explanation of contrary-To-Fact conditionals. The author attempts to show that universal material implications "have no relevance to contrary-To-Fact conditionals." (staff).
Though the phrase 'x is true of x' is well formed grammatically, it does not express any predicate in the logical sense, because it does not satisfy the principle of reduction for statements containing 'x is true of'. recognition of this allows for solution of russell's paradox without his restrictive theory of types.
It is remarkable that we have to-day a number of philosophers who call themselves subjectivists in moral philosophy. For, although the name “subjectivist” is by no means new, philosophers have reserved it hitherto for their opponents, and usually for imaginary opponents at that. Perhaps the chief cause of the change which has taken place in recent years is the discovery of a distinction between descriptive and emotive meaning. In the past the only form of subjectivism considered by writers on moral (...) philosophy was the suggestion that moral sentences such as “You ought to do that” were statements about the speaker's own attitude; and it was easy to refute this by pointing out that we discuss questions of morals in a way which would be unintelligent, and even unintelligible, if moral judgments were only reports of introspection. But those who now call themselves subjectivists maintain that the peculiarity of moral words is their expressive and evocative power. According to their analysis, a speaker who uses one of these words in an indicative sentence may be stating nothing at all, but is undoubtedly trying to influence others to adopt a certain attitude. This, they say, explains how there can be genuine disagreement about questions of morals and why discussion may produce results. If A tries to evoke one attitude in his hearers and B tries to evoke an incompatible attitude, their utterances are opposed, not indeed like contradictory statements, but rather like the efforts of men engaged in a tug-of-war. (shrink)
