Inductive Logic

All scientific investigation relies on logical reasoning, and it can be important for science communicators to understand the type of logic underlying a particular scientific finding. Inductive logic is one common type of logic used in science. To define inductive logic, it is first necessary to have a firm grasp of what logic is generally, and then it will be possible to specify what kind of logic is inductive.

Logic is generally identified as the principles and relationships of reasoning. Logic concerns argumentation, but not in the everyday sense of people who are angry at one another. Rather, an argument in the logical sense is a set of two or more statements in which at least one (called a premise) is said to be a reason to believe another is true (a conclusion).

Principally, inductive logic can then be distinguished from deductive logic as follows. Deductive arguments are characterized by a necessary relationship between their premises and conclusions. By contrast, inductive arguments offer support for thinking that their conclusions are likely to be true. Thus, the relationship between the premises and conclusion in an inductive argument is characterized by probability.

There are many kinds of inductive arguments. Statistical arguments are often good examples of inductive reasoning, when the conclusion drawn is only probable. A batter who has a high rate of hitting home runs is more likely to hit another than his teammates who have hit few, for example. Arguments based on observation of signs, often predictions, are also common inductive arguments. Weather forecasts are good examples. Other forms of inductive premises are claims by authorities, whose evidence is stronger or weaker depending upon their history or the quality of their arguments and capabilities.

History and tradition can be good predictors, but only when relevant. For instance, the fact that the sun has come up every day throughout history is reason to think it will rise again tomorrow. Evidence of having seen the sun rise in the past is called empirical. It is evidence gained from people's senses and their memory of what these showed. In this way, traditional (past) practices are empirical predictors of future behavior, unless some other evidence or reason can help to predict a variation from traditional practices.

Finally, analogies are frequently used in inductive arguments. Consider that in biology, for example, animals that share characteristics are likely to have a more similar DNA than animals with more differences. Analogies here are relevant in testing, where mice are selected for medical drug studies because of the similarity of their immune system to humans'. Effectively, studies that are successful in mice in combating disease argue by analogy that the same or a similar treatment could be developed to help treat human beings.

Inductive logic is a crucial tool in the study of science and technology. Scientists do not only attempt to make predictions, of course. Inductive reasoning is also crucial in learning how things happened or how they have worked. When someone thinks about a space ship that does not function properly or explodes, for instance, that person often searches creatively for hypotheses that might explain the dysfunction. Once someone has a theory, he or she can create methods for testing that theory.

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