INDUCTION, DEDUCTION, AND THE SCIENTIFIC METHOD
Deductive Reasoning vs. Inductive Reasoning
Deductive reasoning
Deductive reasoning is a basic form of valid reasoning. Deductive reasoning, or deduction, starts out with a general statement, or hypothesis, and examines the possibilities to reach a specific, logical conclusion, according to California State University. The scientific method uses deduction to test hypotheses and theories. "In deductive inference, we hold a theory and based on it we make a prediction of its consequences. That is, we predict what the observations should be if the theory were correct. We go from the general — the theory — to the specific — the observations," said Dr. Sylvia Wassertheil-Smoller, a researcher and professor emerita at Albert Einstein College of Medicine.
Deductive reasoning usually follows steps. First, there is a premise, then a second premise, and finally an inference. A common form of deductive reasoning is the syllogism, in which two statements — a major premise and a minor premise — reach a logical conclusion. For example, the premise "Every A is B" could be followed by another premise, "This C is A." Those statements would lead to the conclusion "This C is B." Syllogisms are considered a good way to test deductive reasoning to make sure the argument is valid.
For example, "All men are mortal. Harold is a man. Therefore, Harold is mortal." For deductive reasoning to be sound, the hypothesis must be correct. It is assumed that the premises, "All men are mortal" and "Harold is a man" are true. Therefore, the conclusion is logical and true. In deductive reasoning, if something is true of a class of things in general, it is also true for all members of that class.
According to California State University, deductive inference conclusions are certain provided the premises are true. It's possible to come to a logical conclusion even if the generalization is not true. If the generalization is wrong, the conclusion may be logical, but it may also be untrue. For example, the argument, "All bald men are grandfathers. Harold is bald. Therefore, Harold is a grandfather," is valid logically but it is untrue because the original statement is false.
Inductive reasoning
Inductive reasoning is the opposite of deductive reasoning. Inductive reasoning makes broad generalizations from specific observations. Basically, there is data, then conclusions are drawn from the data. This is called inductive logic, according to Utah State University.
"In inductive inference, we go from the specific to the general. We make many observations, discern a pattern, make a generalization, and infer an explanation or a theory," Wassertheil-Smoller told Live Science. "In science, there is a constant interplay between inductive inference (based on observations) and deductive inference (based on theory), until we get closer and closer to the 'truth,' which we can only approach but not ascertain with complete certainty."
An example of inductive logic is, "The coin I pulled from the bag is a penny. That coin is a penny. A third coin from the bag is a penny. Therefore, all the coins in the bag are pennies."
Even if all of the premises are true in a statement, inductive reasoning allows for the conclusion to be false. Here's an example: "Harold is a grandfather. Harold is bald. Therefore, all grandfathers are bald." The conclusion does not follow logically from the statements.
Inductive reasoning has its place in the scientific method. Scientists use it to form hypotheses and theories. Deductive reasoning allows them to apply the theories to specific situations.
The Scientific Method
In spite of what I have said so far, is there a particular method we can call THE scientific method? To answer this question it is essential that we first ask another question: what do we mean by science? The word comes from Latin scire, “to know,” and scirecomes from an earlier Latin root meaning “to cut through,” i.e. to take apart, to analyze. But science is more than just knowing by analysis. Science is a process of learning to know the nature of everything in the material world, from atoms to the most complex of living organisms and inanimate objects. Nonmaterial things, like gods, whose existence can be neither confirmed nor disproved, are excluded, for science deals only with those elements of the universe that can be shown, at least potentially, to exist. Science, therefore, is never-ending and always changing. Although its goal is knowledge, it is more than and different from knowledge itself, for knowledge is its product not its essence. Its essence is to doubt without adequate proof. Science is the offspring of philosophy, and differs from it mainly in the methods used in learning to know. As with almost all systems of classification, we can’t draw a sharp distinction between science, as defined here, and other forms of scholarship as sources of knowledge such as the OED, Grove’s Dictionary of Music and Musicians, the Dickson Baseball Diction-ary, etc. or even history, for example. In many respects, history is a science but it is poorly endowed with or even lacks the ability to predict, one of the important things that separates science from other forms of learning.In all respects science is logically incompatible with the belief in a nonmaterial intelligent entity that con-trols the universe and is called God [7, 8], yet many scientists, especially among the chemists and physicists but even among some biologists have such a religious belief. I can think of only three resolutions of this paradox. The scientist’s God either is not an intelligent entity or has no control over the universe. The second is to accept the concept of science as defined here with a part of one’s mind and that of God with another, with an impermeable barrier between the two parts. The third is either not to be a scientist or not to believe in God, i.e. to be an atheist, or euphemistically, a non-believer since among many people ‘atheist’ is a dirty word. The funny thing about these solutions is that they all work! The troublemakers are the zealots, i.e. the proponents of Intelligent Design on the one hand, and the Russian communists’ idiotic attempt to prohibit religion on the other. A firm distinction between the so-called hard and soft sciences, e.g. physics and sociology, can also not be made simply because it is easier to test reality in some more than in other sciences. Science itself, therefore, answers our question with a simple but firm No. There cannot be one method that every kind of scientific study in the field, the library, or the lab-oratory must follow; the things scientists are curious about differ too much from one another for all of them to be studied according to the same or any set of rules or algorithms. Medewar’s caricature of the scientific paper boils down to a matter of beating a dead horse. He labels it inductivist because the authors often present their results without comment and reserve interpretation of them for the Discussion. In the first place, this isn’t induction. Even Bacon, its chief proponent, saw induction mainly as a way to separate particulars from one another into groups of similarities. This is exactly what the taxonomist does. But even if it were induction (the meaning of which seems to depend on who defines it), what’s unscientific about saying, “Here’s what we found. How would you interpret them? Then we’ll tell you what we think”? Shouldn’t a scientific paper be at least as much fun to read as a good detective story? There are plenty of things wrong with the way many scientific papers are written (freight-train adjectives, misplaced clauses, redundancies, mistakes in grammar and/or syntax, teleologisms, etc.), but presenting the results without comment is not one of them. I have a hunch that Medewar was not a lover of who-done-its! The only true scientific method is to use whatever tools we can to make observations, ask and answer questions, solve problems, test a theory, etc., and it doesn’t matter whether we use induction, deduction, or any other kind of reasoning to do so; it would be a heresy to deny the validity of any method that helps us learn to know. Induction, in fact, resembles what prose was to Molierre’s bourgeois gentleman. We use some form of induction in almost every kind of scientific endeavor: no matter how it is defined, induction amounts to making and collating observations. This was Francis Bacon’s great contribution to science, i.e. induction as a path to knowledge through direct observation of nature. Let’s come back now to the chimp and the oran-gutan. Were both scientists? Yes. Was the orangutan more so than the chimp? No. He was only different. Who can say which was better? Are Mayr’s contributions to evolution through ornithology less valuable than Dobzhansky’s through genetics? Was Vesalius less a scientist than Mendel because he des-cribed human anatomy while Mendel did experiments? Both made observations, one by dissection and the other by making hybrids. Both increased our know-ledge of the natural world. Yes, some are better than others; it’s how the game is played. We can’t all play the violin like Heifetz, and the likes of a Copernicus, a Newton, a Darwin, and an Einstein don’t make the headlines every day. But we can all be scientists.
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