Logic 101 for Legal Reasoning

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Transcript of Logic 101 for Legal Reasoning

  • 1. Logic for Legal Reasoning LIBR 430 Week 2
  • 2. Logic for Legal Reasoning Logic and the law are intertwined Law schools dont always teach logical reasoning or argument Most righting and speaking in the legal profession is based upon logical arguments You cannot read case like a lawyer until you understand the basics of logical thinking
  • 3. Logical Reasoning for Lawyers A basic command of logical reasoning is needed to follow most legal arguments Critical to success in the law school classroom Central to effective engagement in Socratic dialog Not required to know the ins and outs of all logical reasoning just the basics
  • 4. Three Forms of Logical Reasoning Every Reader of the Law Should Know Deductive reasoning Proving a conclusion by means of two other propositions By far the most frequently used form of reasoning conclusions under the law Inductive generalization Arriving at sweeping generalizations based upon a smaller, more discrete event Analogy The comparison of two different things in order to draw a conclusions about both (EXTREMELY IMPORTANT IN LAW SCHOOL!)
  • 5. Deductive Reasoning One of two main forms of logical reasoning Important to the legal system and reasoning since this form of reasoning provides a grounded foundation for conclusions Deduction in reasoning in which a conclusion is compelled by facts If A and B are true so must C John is 6 feet tall; Susan is taller than John; Susan must be taller than 6 feet
  • 6. Deduction and Legal Reasoning Syllogistic reasoning is the deductive reasoning that is also used in judicial opinions, briefs and memos Instead of a result being COMPELLED by two FACTS it is instead INFERRED from two PREMISES Major premise + minor premise = conclusion What is true of the universe is true of the particular
  • 7. Example All people sleep (general) so students must sleep (particular) Major premise (general): All people sleep Minor premise (particular): Students are people Conclusion: Students sleep
  • 8. Syllogism lies at the heart of legal writing Griswold v. Connecticut A law is unconstitutional if it impacts the zone of privacy created by Bill of Rights. The law banning contraceptives impacts the zone of privacy created by the Bill of Rights. Therefore the law banning contraceptives is unconstitutional
  • 9. Learn to Think in Syllogisms Daily study is required to be a good student I study daily I am a good student If you are not making syllogistic arguments in your case briefs, legal writing, exams etc you will never succeed in law school.
  • 10. How do you develop the skill ofthinking/reasoning in syllogisms? Construct a general rule as a major premise Widely known legal rule Applicable and relevant to your facts Construct a minor premise for your facts Draw a conclusion based upon how that general rule applies to the minor premise about facts
  • 11. Example Major premise: The First Amendment protects certain kinds of expression from being banned Nude dancing is a form of expression protected by the first amendment The government cannot ban people from dancing without clothing
  • 12. Think of a Generic Syllogism for Each Area of Law Constitutional (rights of individuals) [Doing something] is protected by [constituional basis] [Plaintiff] was [Doing something] [Plaintiff] is protected by [constitutional basis] Can you think of one for criminal law? Contracts? Torts?
  • 13. Not always easy to find in judicial opinions Excess language may obscure the logical reasoning Doesnt mean its bad writing The law, after all, is complex! Once you find it, however, you can argue its validity or applicability--so you have to find it!
  • 14. Example This right of privacy, whether it be founded in the Fourteenth Amendments concept of personal liberty and restrictions upon state action, as we feel it is, or, as the District Court determined, in the Ninth Amendment reservation of rights to the people, is broad enough to encompass a woman decision whether or not to terminate her pregnancy.
  • 15. The syllogism? Major Premise? Minor Premise? Conclusion?
  • 16. Major Premise: The right of privacy is guaranteed by the Fourteenth or Ninth Amendment. Minor Premise: A womans decision to terminate her pregnancy is protected by the right of privacy. Conclusion:Therefore, a womans decision whether to terminate her pregnancy is protected by the Fourteenth or Ninth Amendment.
  • 17. Sometimes judges leave things out that you should know No matter how much rearranging of language you do you may be stuck! Efficiency means stuff gets left out especially when so widely known that both parties would accept that fact Be on the lookout for this kind of scenario
  • 18. Pollysyllogisms Multiple syllogisms must be constructed in order to establish a conclusion Most judicial opinions are written this way Rule based syllogisms get stacked upon one another in order to create holdings Hosanna-Tabor case
  • 19. Warning! Watch out for flawed syllogisms Sometimes the major premise is not major enough If not encompassing it leaves room for an opening in order to undercut the argument Look for qualifying language like some, sometimes, many, once, occasionally, oftentimes etc.
  • 20. Example Major Premise: Some forms of expression are protected by the first amendment Minor Premise: Nude dancing is a form of expression Conclusion: Nude dancing is protected by the first amendment
  • 21. Inductive Reasoning Big, general principles are divined from individual smaller events Opposite of deductive Instead of general to specific induction is taking specific to general The world is predictable enough to arrive at conclusions based upon specific incidents that frequently occur Not guaranteed
  • 22. Example Jane studies every day and is a good student. Tom studies every day and is a good student. Angela studies every day and is a good student. Good students study every day.
  • 23. When is inductive reasoning used? When there is insufficient precedent No clear statute Basically, no major premise! Easiest to understand but hardest to use Law students oftentimes default to it when in classroom dialog One example of the opposite of the particular statements (e.g. Randy is a good student but he never studies) is all that is needed to undermine them
  • 24. Analogy Plays a critical role in oral argument before appellate panels and most law school classrooms Used to test the validity of an argument Mastering the use of analogy is one of the most crucial aspects of thinking/reading like a lawyer (as well as law school and legal practice)
  • 25. Structure of Analogy A has characteristic C B has characteristic C A also has characteristic D Because A and B share C they must share D as well
  • 26. Useful to legal reasoning Current cases get compared to new ones Established precedent gets applied to new factual scenarios Critical to judicial opinions
  • 27. How does it work? Establish similarity between two cases Announce the rule of law embedded in the first case Apply the rule of law to the second case Process of reasoning from particular to particular The reasoning process becomes more about establishing or debunking the similarities between the two cases
  • 28. Example You are issued a citation for driving a scooter without a helmet Case 1 prohibits riding a motorcycle without a helmet Case 2 allows riding a bike without a helmet Is a scooter a really fast