Deductive Quotes & Sayings

Conan Doyle deluded a century of readers into thinking we're all deductive geniuses. — Rob Thomas

Theologians, and religionists in general, start with a fantasy premise and then proceed to apply rigorous formal logic to tease out its implications. Stark himself points out that "theology consists of formal reasoning about God." This is admirably exact. Theologians, beginning with a wished-for creation of their own minds, analyze that creation's characteristics by rigorous application of the principles of formal - that is, deductive - logic. — Andrew Bernstein

all learners benefited from the deductive instruction regardless of differences in aptitude. — Patsy M. Lightbown

The word 'proof' should strictly only be used when we are dealing with deductive inferences.... Popper claimed that scientists only need to use deductive inferences.... So if a scientist is only interested in demonstrating that a given theory is false, she may be able to accomplish her goal without the use of inductive inferences.... When a scientist collects experimental data, her aim might be to show that a particular theory...is false. She will have to resort to inductive reasoning.... So Popper's attempt to show that science can get by without induction does not succeed. — Samir Okasha

Aristotle writes that persuasion is based on three things: the ethos, or personal character of the speaker; the pathos, or getting the audience into the right kind of emotional receptivity; and the logos, or the argument itself, carried out by abbreviated syllogisms, or something like deductive syllogisms, and by the use of example. — Randal Marlin

If I were to sit normally, my deductive skills will immediately be reduced by roughly 40%
-L — Tsugumi Ohba

A system is said to be coherent if every fact in the system is related every other fact in the system by relations that are not merely conjunctive. A deductive system affords a good example of a coherent system. — Susan Stebbing

I'm not a great deductive thinker, but I will admit to having competence in a very wide range of things - not being afraid to try to write about baseball, choral music and dinosaurs in the same week and see connections among them. — Stephen Jay Gould

It is absurd to try to confine our knowledge and belief to matters which are conclusively established by sound deductive arguments. The demand for certainty will inevitably be disappointed, leaving skepticism in command of almost every issue. — J. L. Mackie

All that the world needs most today, is combined in the most deductive manner in his art; the three great stimulants of exhausted people: brutality, artificiality, and innocence (idiocy). — Friedrich Nietzsche

No discussion of logic is complete without a refresher course in the difference between inductive and deductive reasoning. By its strictest definition, inductive reasoning proves a general principle - your idea worth spreading - by highlighting a group of specific events, trends, or observations. In contrast, deductive reasoning builds up to a specific principle - again, your idea worth spreading - through a chain of increasingly narrow statements. — Jeremey Donovan

For it is necessary in every practical science to proceed in a composite (i.e. deductive) manner. On the contrary in speculative science, it is necessary to proceed in an analytical manner by breaking down the complex into elementary principles. — Thomas Aquinas

The power of the deductive network produced in physics has been illustrated in a delightful article by Victor F. Weisskopf. He begins by taking the magnitudes of six physical constants known by measurement: the mass of the proton, the mass and electric charge of the electron, the light velocity, Newton's gravitational constant, and the quantum of action of Planck.

He adds three of four fundamental laws (e.g., de Broglie's relations connecting particle momentum and particle energy with the wavelength and frequency, and the Pauli exclusion principle), and shows that one can then derive a host of different, apparently quite unconnected, facts that happen to be known to us by observation separately .... — Gerald Holton

Through all the years of experimenting and research, I never once made a discovery. I start where the last man left off. All my work was deductive, and the results I achieved were those of invention pure and simple. — Thomas A. Edison

The future cannot be predicted, but futures can be invented. It was man's ability to invent which has made human society what it is. The mental processes of inventions are still mysterious. They are rational but not logical, that is to say, not deductive. — Dennis Gabor

Lewis helps us to appreciate that apologetics need not take the form of deductive argument. Instead, apologetics can be an invitation to step into the Christian way of seeing things, and explore how things look when seen from its standpoint. Lewis's approach says, "Try seeing things this way!" If worldviews or metanarratives can be compared to lenses, which of them brings things into sharpest focus? — Alister E. McGrath

The deductive method is the mode of using knowledge, and the inductive method the mode of acquiring it. — Henry Mayhew

Facts - behind them lies the whole fabric of deductive truth. — Peter Sellers

Mr Baley", said Quemot, "you can't treat human emotions as though they were built about a positronic brain".
"I'm not saying you can. Robotics is a deductive science and sociology an inductive one. But mathematics can be made to apply in either case. — Isaac Asimov

It was a good answer that was made by one who when they showed him hanging in a temple a picture of those who had paid their vows as having escaped shipwreck, and would have him say whether he did not now acknowledge the power of the gods, - 'Aye,' asked he again, 'but where are they painted that were drowned after their vows?' And such is the way of all superstition, whether in astrology, dreams, omens, divine judgments, or the like; wherein men, having a delight in such vanities, mark the events where they are fulfilled, but where they fail, though this happens much oftener, neglect and pass them by. — Francis Bacon

Our society's almost doctrinal emphasis upon deductive reasoning, convergent thinking and selective retention perversely excludes divergent thinking, approximation and, importantly, guessing. If we are truly to understand the adolescent mind and develop effective ways to minimize the effects of risk-taking behaviour, we really need to understand these processes and engage with them. There is no logic involved with drug-taking and gambling. Adults can learn, too; understanding these mechanisms will also allow us to encourage creativity and value the spontaneity so characteristic of the adolescent mind. — Tony Little

Mathematics, in its widest significance, is the development of all types of formal, necessary, deductive reasoning. — Alfred North Whitehead

Todd, trust math. As in Matics, Math E. First-order predicate logic. Never fail you. Quantities and their relation. Rates of change. The vital statistics of God or equivalent. When all else fails. When the boulder's slid all the way back to the bottom. When the headless are blaming. When you do not know your way about. You can fall back and regroup around math. Whose truth is deductive truth. Independent of sense or emotionality. The syllogism. The identity. Modus Tollens. Transitivity. Heaven's theme song. The night light on life's dark wall, late at night. Heaven's recipe book. The hydrogen spiral. The methane, ammonia, H2O. Nucleic acids. A and G, T and C. The creeping inevibatility. Caius is mortal. Math is not mortal. What it is is: listen: it's true. — David Foster Wallace

Mathematics - this may surprise or shock some - is never deductive in creation. — Paul Halmos

For the emergent process, as noted by the geneticist Theodore Dobzhansky, is neither random nor determined but creative. Just as in human order, creativity is neither a rational deductive process nor the irrational wandering of the undisciplined mind but the emergence of beauty as mysterious as the blossoming of a field of daisies out of the dark Earth. — Thomas Berry

Some things cannot be perceived with the five senses; they can only be conceived by the Holy Spirit. Some things cannot be deduced via deductive reasoning; they can only be imagined by the Holy Spirit. Some things cannot be learned by logic; they can only be revealed by the Holy Spirit. — Mark Batterson

The sign painter had guts, maybe. Good taste, no. Anyone with a taste for chocolate Paydays had been spending too much time in the sun. We've stumbled on another find, I believe, Sergeant. Inspector, I stand amazed- your deductive acumen is exceeded only by your good looks and the extraordinary length of your reproductive organ. — Stephen King

I start with an image, then I go from the image toward exploring the situation. Then I write a scene, and from the scene I find the character, from the character I find the larger plot. It's like deductive reasoning - I start with the smaller stuff and work backward. — Dan Chaon

Now we can see what makes mathematics unique. Only in mathematics is there no significant correction - only extension. Once the Greeks had developed the deductive method, they were correct in what they did, correct for all time. Euclid was incomplete and his work has been extended enormously, but it has not had to be corrected. His theorems are, every one of them, valid to this day. — Carl B. Boyer

The mathematician starts with a few propositions, the proof of which is so obvious that they are called self-evident, and the rest of his work consists of subtle deductions from them. The teaching of languages, at any rate as ordinarily practiced, is of the same general nature authority and tradition furnish the data, and the mental operations are deductive. — Thomas Huxley

Here are the basic principles of Constructivism as practiced by Kronecker and codified by J.H. Poincare and L.E.J. Brouwer and other major figures in Intuitionism: (1) Any mathematical statement or theorem that is more complicated or abstract than plain old integer-style arithmetic must be explicitly derived (i.e. 'constructed') from integer arithmetic via a finite number of purely deductive steps. (2) The only valid proofs in math are constructive ones, with the adjective here meaning that the proof provides a method for finding (i.e., 'constructing') whatever mathematical entities it's concerned with. — David Foster Wallace

I am delighted to know that Principia Mathematica can now be done by machinery ... I am quite willing to believe that anything in deductive logic can be done by machinery. — Bertrand Russell

Whoever builds his faith exclusively on demonstrative proofs and deductive arguments, builds a faith on which it is impossible to rely. For he is affected by the negativities of constant objections. Certainty(al-yaqin) does not derive from the evidences of the mind but pours out from the depths of the heart. — Ibn Arabi

If I sound as if I'm always predicting ominous things, it's because I'm a pragmatist. I use deductive reasoning to generalize, and I suppose this sometimes ends up sounding like unlucky prophecies. You know why? Because reality's just the accumulation of ominous prophecies come to life. You have to only open a newspaper on any given day and weigh the good news versus the bad, and you'll see what I mean. — Haruki Murakami

You often show yourself without any faculty of deductive reasoning. — Rafael Sabatini

Your powers of deductive reasoning are stunning," spits Tobias. "Consider me awed. — Veronica Roth

Even science is inductive, relying on observations and best explanations, not always deductive conclusions. — Nabeel Qureshi

If a lack of empirical foundations is a defect of the theory of logical probability, it is also a defect of deductive logic. — David Stove

When you are young in this world, you believe that the class of deductive truths about social matters is larger than it turns out to be. [ ... ] I have discovered, to my infinite regret, that most of the serious debates over the basic principles of any political order have an irreducible empirical content. — Richard Allen Epstein

During all those years of experimentation and research, I never once made a discovery. All my work was deductive, and the results I achieved were those of invention, pure and simple. I would construct a theory and work on its lines until I found it was untenable. Then it would be discarded at once and another theory evolved. This was the only possible way for me to work out the problem. — Thomas A. Edison

Inferences of Science and Common Sense differ from those of deductive logic and mathematics in a very important respect, namely, when the premises are true and the reasoning correct, the conclusion is only probable. — Bertrand Russell

Geometry is a Deductive Science. — John Stuart Mill

You should carefully study the Art of Reasoning, as it is what most people are very deficient in, and I know few things more disagreeable than to argue, or even converse with a man who has no idea of inductive and deductive philosophy. — William John Wills

The discovery of geometry had intoxicated them, and its a priori deductive method appeared capable of universal application. They would prove, for instance, that all reality is one, that there is no such thing as change, that the world of sense is a world of mere illusion; and the strangeness of their results gave them no qualms because they believed in the correctness of their reasoning. — Bertrand Russell

All mathematical proofs must be deductive. Each proof is a chain of deductive arguments, each of which has its premises and conclusion. — Morris Kline

Mathematics has two faces: it is the rigorous science of Euclid, but it is also something else. Mathematics presented in the Euclidean way appears as a systematic, deductive science; but mathematics in the making appears as an experimental, inductive science. Both aspects are as old as the science of mathematics itself. — George Polya

It's all over, it's all over,' I muttered to myself. My grief resembled that of a fainthearted student who has failed an examination: I made a mistake! I made a mistake! Simply because I didn't solve that X, everything was wrong. If only I'd solved that X at the beginning, everything would have been all right. If only I had used deductive methods like everyone else to solve the mathematics of life. To be half-clever was the worst thing I could have done. I alone depended upon the inductive method, and for the simple reason I failed. — Yukio Mishima

Now this foreknowledge cannot be elicited from spirits; it cannot be obtained inductively from experience, nor by any deductive calculation. — Sun Tzu

Social psychology, the science of how people behave toward one another, is often a mishmash of interesting phenomena that are "explained" by giving them fancy names. Missing is the rich deductive structure of other sciences, in which a few deep principles can generate a wealth of subtle predictions - the kind of theory that scientists praise as "beautiful" or — Steven Pinker

Without deductive logic science would be entirely useless. It is merely a barren game to ascend from the particular to the general, unless afterwards we can reverse the process and descend from the general to the particular, ascending and descending like angels on Jacob's ladder. — Alfred North Whitehead

The intellectual equipment needed for the job of the future is an ability to define problems, quickly assimilate relevant data, conceptualize and reorganize the information, make deductive and inductive leaps with it, ask hard questions about it, discuss findings with colleagues, work collaboratively to find solutions and then convince others. — Robert Reich

There is nothing distinctively scientific about the hypothetico-deductive process. It is not even distinctively intellectual. It is merely a scientific context for a much more general stratagem that underlies almost all regulative processes or processes of continuous control, namely feedback, the control of performance by the consequences of the act performed. In the hypothetico-deductive scheme the inferences we draw from a hypothesis are, in a sense, its logical output. If they are true, the hypothesis need not be altered, but correction is obligatory if they are false. The continuous feedback from inference to hypothesis is implicit in Whewell's account of scientific method; he would not have dissented from the view that scientific behaviour can be classified as appropriately under cybernetics as under logic. — Peter Medawar

A detective who uses his deductive powers to corner a suspect and then does nothing to stop them from committing suicide is no better than a murderer himself. - Kudo Shinichi — Gosho Aoyama