Logic: Designed as an Introduction to the Study of ReasoningW. Allen, 1864 - 209 σελίδες |
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Σελίδα 37
... triangle , " " that which has three angles . " These definitions are usually found in dictionaries . 2. An Essential Definition . This has been called by logi- cians the definition of the thing , and explains an object by pointing out ...
... triangle , " " that which has three angles . " These definitions are usually found in dictionaries . 2. An Essential Definition . This has been called by logi- cians the definition of the thing , and explains an object by pointing out ...
Σελίδα 45
... but only some animals are horses . These remarks on propositions may be illustrated by dia- grams . Take the example , " Every horse is an animal . " If we suppose all horses enclosed in a triangle , and OF THE CLASSES OF PROPOSITIONS . 45.
... but only some animals are horses . These remarks on propositions may be illustrated by dia- grams . Take the example , " Every horse is an animal . " If we suppose all horses enclosed in a triangle , and OF THE CLASSES OF PROPOSITIONS . 45.
Σελίδα 46
... triangle , and all animals in a circle , then the preceding assertion , if true , would require that the whole triangle be contained in the circle . Thus : - Here the whole of the horses are spoken of ; hence the whole of the triangle ...
... triangle , and all animals in a circle , then the preceding assertion , if true , would require that the whole triangle be contained in the circle . Thus : - Here the whole of the horses are spoken of ; hence the whole of the triangle ...
Σελίδα 47
... triangle coincides with the circle , and therefore none of the circle coincides with the triangle . Lastly , Take the proposition , " Some islands are not fertile . " Enclose the islands in a triangle , and the fertile places in a ...
... triangle coincides with the circle , and therefore none of the circle coincides with the triangle . Lastly , Take the proposition , " Some islands are not fertile . " Enclose the islands in a triangle , and the fertile places in a ...
Σελίδα 57
... triangle in the circle , as on the left , it follows that the triangle must be contained within the square , thus : - The conclusion of the foregoing syllogism is a universal affirmative ; that is to say , the class of things denoted by ...
... triangle in the circle , as on the left , it follows that the triangle must be contained within the square , thus : - The conclusion of the foregoing syllogism is a universal affirmative ; that is to say , the class of things denoted by ...
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Συχνά εμφανιζόμενοι όροι και φράσεις
act of reasoning admitted affirmed or denied ambiguity animal antecedent argu argument ascertained assertion belongs Cæsar called categorical propositions categorical syllogism Christian circle clusion conclusion conditional proposition conditional syllogism connexion consequent considered Contraposition conversion copula definition denoted deserved death detect and expose disjunctive disjunctive proposition distinct distributed drawn employed Enthymeme error evidence example expressed facts fallacy false Figure genus gism happy Hence HYPOTHETICAL SYLLOGISMS illicit process Induction Inductive philosophy inference instance Julius Cæsar kind language legitimate major premise major proposition major term means ment merely middle term mind minor term miserable mises mode of reasoning Moods mortal nature negative object particular person philosophy predicate principles proof proved province of Logic quadruped reasoning process reduced regular syllogism respecting rules sense shew signification sion sophism Sophist Sorites species supposition syllogistic takes place thing tion triangle true truth tyrants universal affirmative universal proposition validity whole words
Δημοφιλή αποσπάσματα
Σελίδα 37 - A circle is a plane figure contained by one line, which is called the circumference, and is such that all straight lines drawn from a certain point within the figure to the circumference, are equal to one another.
Σελίδα 147 - When we say, All men are mortal Socrates is a man therefore -•'Socrates is mortal; it is unanswerably urged by the adversaries of the syllogistic f.
Σελίδα 154 - All inference is from particulars to particulars : General propositions are merely registers of such inferences already made, and short formulae for making more : The major premise of a syllogism, consequently, is a formula of this description : and the conclusion is not an inference drawn from the formula, but an inference drawn according to the formula: the real logical antecedent, or...
Σελίδα 108 - Achilles run ten times as fast as the tortoise, yet if the tortoise has the start, Achilles will never overtake him. For suppose them to be at first separated by an interval of a thousand feet: when Achilles has run these thousand feet, the tortoise will have got on a hundred; when Achilles has run those hundred, the tortoise will have run ten, and so on for ever: therefore Achilles may run for ever without overtaking the tortoise.
Σελίδα 152 - When, therefore, we conclude from the death of John and Thomas, and every other person we ever heard of in whose case the experiment had been fairly tried, that the Duke of Wellington is mortal like the rest ; we may, indeed, pass through the generalization, All men are mortal...
Σελίδα 143 - ... again. He believes this in every case which happens to arise; but without looking, in each instance, beyond the present case. He is not generalizing; he is inferring a particular from particulars. In the same way, also, brutes reason.
Σελίδα 108 - ... does not mean any length of time ; it means any number of subdivisions of time. It means that we may divide a thousand feet by ten, and that quotient again by ten, and so on as often as we please ; that there never...
Σελίδα 144 - Logic is not the science of Belief, but the science of Proof, or Evidence. In so far as belief professes to be founded on proof, the office of logic is to supply a test for ascertaining whether or not the belief is well grounded.
Σελίδα 151 - If a man is asked a question, and is at the moment unable to answer it, he may refresh his memory by turning to a memorandum which he carries about with him. But if he were asked, how the fact came to his knowledge, he would scarcely answer, because it was set down in his note-book : unless the book was written, like the Koran, with a quill 1rom the wing of the angel Gabriel.