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Formal Logic: or, the Calculus of inference, necessary and probable
Augustus De Morgan
Visualització completa - 1847
admit affirmative againſt alſo alteration anſwer appears applied argument aſſertion ball belief called caſe chapter common complex concluſion conſequence conſidered contained contrary definite deny diſtinction eight equally example exiſt expreſſed fallacy falſe figure firſt forms four fyllogiſm give given greater Hamilton happen idea identical inference inſtance itſelf knowledge language laſt laws leaſt leſs letters logic manner matter meaning middle term mind mode moſt muſt neceſſary negative never notion object particular perſon poſſible preceding predicate premiſes principle probability proceed propoſition prove quantity queſtion reader reaſon reference relation reſult rule ſaid ſame ſay ſecond ſee ſenſe ſhall ſhould ſhow ſimple ſome ſpeak ſpecies ſtate ſubject ſuch ſuppoſe ſyſtem teſtimony theſe thing third thoſe thought tion true truth univerſal uſe uſually whole write
Pàgina 266 - ... fcenes, he feems to produce without labour, what no labour can improve* In tragedy he is always ftruggling after fome occafion to be...
Pàgina 160 - By degree of probability we really mean, or ought to mean, degree of belief. It is true that we may, if we like, divide probability into ideal and objective, and that we must do so, in order to represent common language.
Pàgina 161 - An omniscient being would never employ probable inferences, since every proposition would be known to be certainly true or certainly false. Beings lacking omniscience must rely on probabilities, since their knowledge is incomplete, and probability measures their ignorance. When we feel altogether...
Pàgina 64 - A is greater than B, B is greater than C, therefore A is greater than C.
Pàgina 15 - I would not dissuade a student from metaphysical inquiry ; on the contrary I would rather promote the desire of entering on such subjects ; but I would warn him, when he tries to look down his own throat with a candle in his hand, to take care that he does not set his own head on fire...
Pàgina 111 - B, or if C is D, E is F ; But either A is B, or C is D ; /. E is F.
Pàgina 225 - there is no such thing as a classification of the ways in which men may arrive at an error: it is much to be doubted whether there ever can be."* Surely, there can be no conclusive and comprehensive classification.
Pàgina 316 - A it affirms of this, tJvese, all — Whilst E denies of any : I, it affirms, whilst 0 denies, Of some (or few or many). Thus A affirms, as E denies, And definitely either : Thus I affirms, as O denies, And definitely neither. A half, left semi-definite, Is worthy of its score ; U, then, affirms, as Y denies, This, neither less nor more.
Pàgina 24 - ... Whately, understands by a Real Definition one which contains less than the Nominal Definition, provided only that what it contains is sufficient for distinction. "By real definition I mean such an explanation of the word, be it the whole of the meaning or only part, as will be sufficient to separate the things contained under that word from all others. Thus the following, I believe, is a complete definition of an elephant: An animal which naturally drinks by drawing the water into its nose, and...