LEGAL REASONING AND LOGIC
Lawyers are often thought of as having logical minds. This gives the impression that legal reasoning itself is or should be governed by logic. Certainly, logic plays an important role in legal reasoning but as we will see, it is only part of the story.
When we refer to logic we are often thinking of the deductive form or argument known as syllogism. It goes like this: All men are mortal (Major Premise): Paul is a man (Minor Premise); Therefore Paul is mortal (Conclusion).
A lawyer advising his client as to the application of a detailed statutory provision will employ this type of reasoning. The statute is the major premise, the lawyer identifies his case as falling within the statute and then deduces his conclusion the way in which it applies to his client. For example, the Criminal Code provides that the offence of stealing attracts the punishment of three years imprisonment if found liable. If A has stolen (with all the elements of the offence being present). One may then conclude that A is liable to three years imprisonment.
Deductive logic is only applicable once a clear major premise has been established. If the source is not a statute but case law, no major premise is likely to be clear from just one case decision. Instead the lawyer would have to examine cases to find a major premise which underlies them all. He will have to reason from particular case decisions to a general proposition. This form of reasoning is often referred to as inductive logic since the reasoning is from the particular proposition to the general conclusion. Thus, a lawyer advising on the application of case law to a particular situation will employ, first, inductive reasoning to find a general proposition of law, and then deductive reasoning to determine how it applies to the facts.