How Is Logic Useful in the Study of Law?

Logic is key in the study of law.

In the practice of their profession, lawyers consistently use arguments, both verbally and in writing. Arguments require logic to be clear and acceptable to a judge and jury. Consequently, the study of logic is essential to the study of law.

Deductive Reasoning

Lawyers use deductive reasoning in case analysis. Deductive reasoning mandates that you develop a general, broad theory about the case and then attempt to prove the theory by relating it to a specific person or fact in the case. When the general theory applies to that person or fact realistically, then the theory is considered valid and the outcome of the deductive reasoning is true. Lawyers must prove the truth of their arguments to judges and juries.

Syllogism

A syllogism is the logical process in deductive reasoning that determines the outcome of the argument a lawyer is making. The syllogism is useful in the study of law because it helps law students learn how to formulate a hypothesis about a case and map the paths of their arguments.

For example, you can make the broad argument that anyone driving faster than 100 miles per hour in the United States is breaking the law. Then, using a syllogism with deductive reasoning, you can make the argument more specific to the person in the case by saying that he was driving in excess of 100 miles per hour. The final step is the logical conclusion that arises from the first two arguments: The person broke the law.

Polysyllogisms

A polysyllogism is two or more syllogisms used to formulate an argument in a case. Multiple syllogisms support one another in an argument and increase in specifics as the argument progresses. This pattern of logic is useful in the study of law because it allows the student to understand the use of multiple arguments to reveal the truth.

Inductive Reasoning and Generalizing

Unlike deductive reasoning that is supported by a chain of facts and proved to be valid, inductive reasoning using generalization only suggests that the outcome could occur. The key for the student studying law is gathering enough known broad facts to support an outcome that could be true or applied to specific facts, thereby gaining support for the argument.

Inductive Reasoning and Analogy

Inductive reasoning using analogy is helpful in the study of law because it teaches students to apply known case law to current cases. Using the principles of inductive reasoning with analogy, the law student applies the rulings of one case to a new case--thus encouraging a judge and jury to make a similar ruling in the new case.

References

• Lawyerist: Use Logic to Win Arguments
• Changing Minds: Deductive Reasoning

Resources

• Stanford Encyclopedia of Philosophy: Classic Logic