Inductive & Deductive Models
Science advances through the rigorous application of the guidelines, principles, and procedures of the scientific method. This approach to studying the world around us utilizes two types of logical reasoning: inductive and deductive. Inductive reasoning occurs when one reasons from specific observations to theorize general principles. Deductive reasoning occurs when one reasons from general principles to specific applications. Neither type of logical reasoning is superior; both are necessary in order for the researcher to be able to transform observations of the real world into empirically testable hypotheses. Both types of reasoning are subject to error, however. The scientist must be careful to apply the various tools of critical thinking to the reasoning process in order to develop a theory that is both objective and verifiable.
One of the basic goals of sociology and other behavioral and social sciences is to describe, explain, and predict behavior. Before this goal can be met, however, behavior first needs to be observed in the real world. For example, I may notice that when I feed my cats "Happy Kitty" salmon dinner, they come running. Similarly, I may notice that students in my class who work well on their own tend not to work as well when required to work in a group setting. Or, I may notice that when I go to the Quick Mart for a quart of milk that people who purchase lottery tickets always appear as if they can ill afford the purchase. I may tuck any of these specific observations into the back of my mind and think about them no more. Or, I might become curious and wonder what the implication of these observations might be. For example, I may decide that my cats enjoy the flavor of "Happy Kitty" salmon dinner, and feed it to them more often. Similarly, I may decide that I need to add a lecture on team building principles to my course curriculum so that people can work more productively and effectively within small, mandated groups. Or, I may develop a theory relating socioeconomic information to the probability and consequences of lottery ticket purchase. All of these are examples of inductive reasoning: a type of logical reasoning in which inferences and general principles are drawn from specific observations or cases. Inductive reasoning is a foundation of the scientific method and enables the development of testable hypotheses from particular facts and observations.
Inductive reasoning is not the only logical process by which people reach conclusions, however. Deductive reasoning is another type of logical reasoning in which one demonstrates that a conclusion must necessarily follow from a sequence of premises, the first of which is a self-evident truth or agreed-upon data point or condition. Deductive reasoning is the foundation upon which predictions are drawn from general laws or theories. For example, if I know that cats enjoy eating fish in general, I may purchase a can of tuna the next time I need to tempt a finicky feline appetite. Similarly, if I know that people who work well independently often have difficulty working in groups, I may include a module on team building in my course curriculum. Or, based on my knowledge of the sociological research literature on lottery ticket purchasing behavior, while standing in line at the Quick Mart with my quart of milk I might look around at my fellow shoppers and predict which of these individuals will purchase a lottery ticket and which of them will not. The difference between deductive and inductive reasoning is shown in Figure 1.
Both inductive and deductive reasoning are important to the theory building process and the scientific method. The scientific method comprises general procedures, guidelines, assumptions, and attitudes required for the organized and systematic collection, analysis, interpretation, and verification of data that can be verified and reproduced. The goal of the scientific method is to articulate or modify the laws and principles of a science. Steps in the scientific method include problem definition based on observation and review of the literature, formulation of a testable hypothesis, selection of a research design, data collection and analysis, extrapolation of conclusions, and development of ideas for further research in the area.
As shown in Figure 2, both inductive and deductive reasoning are essential to the theory building process. Empirical research is an important part of this process. The design of a research study starts with a theory based on real world observation. For example, from personal experience with the types of cat food my cats like to eat, I may develop a preliminary theory that cat food containing some type of fish as its main ingredient is more likely to tempt their appetites than are other kinds of cat food. This preliminary theory is based on the inductive reasoning process that I used to extrapolate my observations of what my cats have liked to eat in the past to a prediction of what my cats might like to eat in the future. Based on my observations and my preliminary theory, I could then develop a hypothesis about the relationship between my cats' behavior and the type of food that I offer them. This hypothesis would be an empirically-testable declaration that certain variables and their corresponding measure are related in a specific way proposed by a theory. In this example, my hypothesis might be that my cats prefer food that contains fish as the primary ingredient. To assist in the development of a testable hypothesis that would lead to generalizable and repeatable results, I may want to further refine the operational definitions in the hypothesis. For example, based on other previous observations I may have noticed that my cats prefer canned food to kibble, or that they prefer the "Happy Kitty" brand of canned food to the "Sour Puss" brand. Based on these observations and the concomitant inductive reasoning process, I might choose to limit my hypothesis to deal only with "Happy Kitty" brand cat food. Therefore, my tentative hypothesis might be that my cats prefer fish-flavored varieties of "Happy Kitty" cat food to other varieties of "Happy Kitty." This hypothesis could be in empirically tested by simultaneously offering my cats a bowl of "Happy Kitty" and salmon and a bowl of "Happy Kitty" beef stew. If the results of my experiment indicate that my hypothesis is correct, I might extrapolate these results deductively and purchase a can of "Happy Kitty" shrimp-and-gravy cat food.
As can be seen in Figure 2, the advancement of science typically depends on both the inductive and deductive reasoning processes. My personal observations -- whether they be about my cats' preferences and food, my students' ability to work well in groups, or the general characteristics of people who purchase lottery tickets -- and the concomitant application of the inductive reasoning process give me little more than empirically based personal opinion in the form of a preliminary theory. It is not until I articulate a testable hypothesis and subject my theory to the rigors of the scientific method, that I can apply the deductive reasoning process and determine whether or not my theory is likely...
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