What Is Inductive Logic?

Jessica Ellis

Inductive logic is a form of reasoning that uses premises or observations to draw a likely conclusion. Unlike deductive logic, which guarantees the truth of a conclusion based on incontrovertible evidence, inductive logic can at best suggest that a conclusion is highly probable based on the premises. Since inductive reasoning is open to somewhat general and non-specific premises, the possibility of bias and incorrect conclusions is often quite high. Nevertheless, inductive logic is often used to make arguments for everything from buying decisions to legislation, since it is far easier to construct than deductive arguments.

Inductive logic uses observations to draw a likely conclusion.
Inductive logic uses observations to draw a likely conclusion.

In order for a statement to be considered inductive, it must have one or several premises that lead to a conclusion. For instance, premises used to reach the conclusion “more people drink cow milk than goat milk” might include “grocery stores carry a higher volume of cow milk than goat milk,” or “there are more dairies that have cows than goats.” While these statements may not be able to conclusively prove that more people drink cow milk, they do make the truth of the statement more likely. If an inductive conclusion has a high degree of probability, it is called a strong argument; a conclusion with a low degree of probability is considered a weak argument.

Even a strong inductive argument can be open to flaws; bias, illogical conclusions, and the simple fact of uncertainty can all lead to an incorrect conclusion despite strong premises. Bias occurs when a person making or evaluating the probability of an argument gives extra weight to or discounts certain premises based on outside circumstances, such as personal experience. If, for instance, a person has been bitten by a poodle, he or she may believe that all poodles are vicious and be less likely to adopt one. Illogical conclusions can occur when all premises are objectively true, but the conclusion drawn from them does not follow logically; for example, while “all poodles are dogs” may be true, it doesn't logically follow that “all dogs are poodles.”

The biggest vulnerability of inductive logic is its inherent uncertainty. Even with strong premises and a logical conclusion, an inductive argument always has the possibility of being untrue. Horse-racing handicappers experience this issue on a regular basis, as even a heavily favored horse with a perfect record and a poor field of opponents can have a bad race and end up last, regardless of the perceived probability of winning. The vulnerability of inductive arguments is also critically important in courtrooms, since few cases provide only deductive and unmistakable evidence.

Since the world is full of uncertainty and diverse interpretations, many people run up against inductive reasoning when making decisions. When attempting to determine the validity of inductive logic, it is important to examine each premise for potential bias, illogicality, and specificity. If the premises can be reasonably judged to be unbiased and logical, it is then necessary to see if the conclusion is a logical assumption from the evidence. Finding that the conclusion is logical, it is then important to determine how probable the conclusion is, based on the strength and amount of premises. Even after all this examination, it is important to remember that inductive logic can only lead to a thoroughly educated guess, and never to the definitive, undeniable truth.

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