Logic

“ It will now be understood that Logic is the all-animating spirit of all the sciences, and its categories the spiritual hierarchy. They are the heart and centre of things: and yet at the same time they are always on our lips, and, apparently at least, perfectly familiar objects. ”

“ A logical theory may be tested by its capacity for dealing with puzzles, and it is a wholesome plan, in thinking about logic, to stock the mind with as many puzzles as possible, since these serve much the same purpose as is served by experiments in physical science. ”

“ We may conclude with logic as sound and certain as is used in any scientific deduction, that every sense, faculty, and hope of the human soul has an objective reality in relation to which it is developed as surely as the wing argues an atmosphere, or the eye an ether. ”

“ But since my logic aims to teach and instruct the understanding, not that it may with the slender tendrils of the mind snatch at and lay hold of abstract notions (as the common logic does) , but that it may in very truth dissect nature, and discover the virtues and actions of bodies, with their laws as determined in matter; so that this science flows not merely from the nature of the mind, but also from the nature of things; ”

“ Whether the Absolute does or does not exist, is it, either in idea or reality, of any use to us? The reply is that its value lies in this, that it reveals to us the nature of reality and the meaning of truth. Logic is the creative power of thought which leads us to the discovery of higher and higher degrees of reality. ”

“ Logic aims to instruct the human mind as to its own nature and processes; it will lay bare the interior working of our mind for our guidance. The object of [Pg 182] the study of logic is thought, its nature, and its proper classification. ”

“ Any man of sense has only to open his eyes, or to observe himself within, to appreciate how all original knowledge is of the concrete, the definite, the individual. This, I say, is what the traditional method in logic seems to imply. ”

“ are the axioms of logic adequate to reality, or are they measures and means by which alone we can, create realities, or the concept " reality "? ”

“ Other researchers perceived logic as a product of our experience, in particular thinking, as this applies to our self-constitution in the natural world and the world we ourselves created. As a corpus of rules and criteria, logic applies to language, but there is a logic of human actions, a logic of art, a logic of morals, etc., described by rules for preserving consistency, maintaining integrity, facilitating causal inference and other relevant cognitive operations, such as articulating a hypothesis or drawing conclusions. ”

“ Logic is not a theory but a reflexion of the world. ”

“ For my own part, I have finally found myself compelled to give up the logic, fairly, squarely, and irrevocably. It has an imperishable use in human life, but that use is not to make us theoretically acquainted with the essential nature of reality—just what it is I can perhaps suggest to you a little later. ”

“ Our conception of logic wishes to show that all causes and effects are matter of the same kind, and that our faculty of reasoning is a matter of fact thing which brooks no mysteries or metaphysical dreams. ”

“ But by what rules of logic we make these inferences, it is impossible to show, nay, it is impossible to show how our sensations and thoughts can give us the very notion and conception either of a mind or of a faculty. ”

“ Whether, therefore, we conform to the practice of those who have made the subject their particular study, or to that of popular writers and common discourse, the province of logic will include several operations of the intellect not usually considered to fall within the meaning of the terms Reasoning and Argumentation. ”

“ If you would interpret the riddle of human motives, put no confidence in logic. The principles of logic are founded on the psychology of Anyone. And Anyone is a mechanical waxwork, an intellectual abstraction, a thing without a soul or a sub-consciousness. ”

“ Values, whether ethical or logical, without an examination and formulation of their ground, relations, origin, and interconnection, would be merely rules of thumb, popular phrases, or pastoral precepts. The actual methodology of the sciences or applied logic is logic as art. ”

“ The sole object of Logic is the guidance of one's own thoughts: the communication of those thoughts to others falls under the consideration of Rhetoric, in the large sense in which that art was conceived by the ancients; or of the still more extensive art of Education. ”

“ What is called formal logic is animated with the hope of extracting these formulations directly from an analysis of the procedure of thought. The most general logical principles which have appeared in the historical development of formal logic are definition, self-evidence, inference, and observation. ”

“ The employment of the word Logic to denote the theory of Argumentation, is derived from the Aristotelian, or, as they are commonly termed, the scholastic, logicians. ”

“ To logic on the other hand it appertains to estimate the value of all these cognitive processes: all questions as to whether the judgments that claim truth actually attain it, as to how cognitions may be rendered consistent, may realise the purposes which we have in knowing, may contribute to the ideals we set before ourselves in knowing, fall into the province of the science which aims at systematising our cognitions into a coherent body of truth. ”

“ The subject-matter of Logic is an inference, judgment or conclusion concerning facts, embodied in a proposition, which is to be examined in relation to the evidence that may be adduced for it, in order to determine whether, or how [Pg 70] far, the evidence amounts to proof. Logic is the science of Reasoning in the sense in which 'reasoning' means giving reasons, for it shows what sort of reasons are good. ”

“ Logic, assuming certain principles to be true of experience, or at least to be conditions of consistent discourse, distinguishes the kinds of propositions that can be shown to agree with these principles, and explains by what means the agreement can best be exhibited. ”

“ It is necessity, in the metaphysical sense, some here utterly obscure kind of ‘logical necessity’ which is the favourite toy of a number of art critics. To those who have some familiarity both with Logic and with Psychology the regular appearance of the term ‘logical’ in describing these relations is the clearest indication that nothing definite or adequately considered is being said. ”

“ But all propositions of logic say the same thing. That is, nothing. ”

“ Even in ordinary conversation, the ideas connected with the word Logic include at least precision of language, and accuracy of classification: and we perhaps oftener hear persons speak of a logical arrangement, or of expressions logically defined, than of conclusions logically deduced from premises. ”

“ Finally, formal logic, with its creed of absolute certitude, abhors the very mention of adventure and risk, the life blood of actual human thinking, which is aroused by doubts and questions, and proceeds by guesses, hypotheses, and experiments, to a decision which is always somewhat arbitrary and subject to the risk of later revision. ”

“ As an art logic may be called the navigation of the sea of thought.
§ 25. The laws of thought are all reducible to the three following axioms, which are known as The Three Fundamental Laws of Thought.
(1) The Law of Identity—
Whatever is, is;
or, in a more precise form,
Every A is A.
(2) The Law of Contradiction—
Nothing can both be and not be;
Nothing can be A and not A.
(3) The Law of Excluded Middle—
Everything must either be or not be;
Everything is either A or not A.
§ 26. ”

“ And, first, I grant the knowledge of all those truths is perfective of the understanding, which are the matter of those arts and sciences, that are built upon stable and immoveable foundations, such as divinity, metaphysics, geometry, together with those unchangeable rules and measures of reason and consequence, which lead us to all other knowledge, and are the subject of that art we term logic. ”

“ The curious phenomena of thought here exhibited illustrate, as above said, a remark I have long ago made on the effect of proper study of logic. Most persons reason well enough on matter to which they are accustomed, and in terms with which they are familiar. But in unaccustomed matter, and with use of strange terms, few except those who are practised in the abstractions of pure logic can be tolerably sure to keep their feet. ”

“ 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. With the claims which any proposition has to belief on the evidence of consciousness—that is, without evidence in the proper sense of the word—logic has nothing to do. ”

“ These fully developed thought-processes are marked off by the use of what is known as the general idea or notion such as man or virtue. Such general ideas when reduced to a precise form as by the logician are spoken of as concepts. And since the science of logic assumes thinking to take place by help of such conceptual products we may also speak of these full or explicit thought-processes as Conceptual Thought. ”

“ Even logical development of a subject is subsidiary to the practical psychological order. Formal logic, the analysis of the process of reasoning, is a cultural study rather than a practical one, save in criticism both of one's own work and another's. ”

“ Positive logic abstains, as we see, from speculating upon the leading principles of knowledge, principles of identity, of contradiction of causality, etc. These kinds of principles are not objects of examination or of discussion. ”

“ In one direction, as applied logic and the logic of induction, the natural associations of ideas have been thoroughly studied, and the methods by which they can be controlled and reduced have been taught with eminent success. ”

“ The criterion of the truths of reason, or those which spring from conceptions, is found in an exact use of the rules of logic. As for ideas or notions, I call real all those the possibility of which is certain ”

“ We have discriminated logic in its wider sense—concerned with the sequence of characteristic functions and attitudes in experience—from logic in its stricter meaning, concerned with the function of reflective thought. ”

“ A reason for a belief is a true proposition from which the truth of the belief follows from which it could be validly inferred. Now these expressions might suggest the idea that I mean to restrict the word "reason," to what, in the strictest sense, might be called a logical reason—to propositions from which the belief in question follows, according to the rules of inference accepted by Formal Logic. ”

“ I believe that one has taken the most important step in philosophy if one has gained a perfect understanding of the nature of logic and its relation to reality or experience. In the first lecture I spoke of that particular misunderstanding of logic which has been called psychologism and consists in the belief that the logical principles are psychological laws of the working of human minds. ”

“ The general terms, then, with which Logic is chiefly concerned, the names of Causes and Kinds, such as gravitation, diseases, social events, minerals, plants and animals, stand for some facts that are, or have been, known, and for a great many other similar ones that have not been, and never will be, known. ”

“ “The whole world is inconceivable to the strict logic of ideas. And yet the world exists to our senses, and we exist in it. There must be a necessity superior to our conceptions. ”

“ Hence it is that bad reasoning as well as good reasoning is possible; and this fact is the foundation of the practical side of logic. ”

“ Their natural good sense may be systematized, their natural logic may be reduced to some rule and order—though it may not be refined it may be practical, it may give power, and develop capacity now dormant. ”

“ It is therefore necessary, in analysing a belief, to look for some other logical form than a two-term relation. Failure to realise this necessity has, in my opinion, vitiated almost everything that has hitherto been written on the theory of knowledge, making the problem of error insoluble and the difference between belief and perception inexplicable.
Modern logic, as I hope is now evident, has the effect of enlarging our abstract imagination, and providing an infinite number of possible hypotheses to be applied in the analysis of any complex fact. ”

“ It is shown that Logic, as the Art of Reasoning, is properly an application of Psychology as the Science of Mind Power. The uses of the Art of Reasoning in Inductive and Deductive Inference and in the formation of correct judgments are dealt with practically. ”