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Logic I · Unit 1

Introduction to Logical and Legal Reasoning

Unit 1 of Logic – I (syllabus: Module I — what logic is; form and content; deduction and induction in the courts; truth, validity and the laws of thought; terms, connotation and denotation; simple enumeration and analogy; logic and law). Below: what the unit covers, the provisions it turns on, and the cases an examiner expects you to name.

What this unit covers

  • When is an argument valid, and what does validity guarantee?
  • Why is logic called a formal science, and what follows for the scope of the subject?
  • What is the relation between inference and implication?
  • What distinguishes deductive from inductive argument, and how does each appear in legal work?
  • What do the three laws of thought state, and what do they not do?
  • How are terms classified, and what is the difference between contrary and contradictory terms?
  • What is simple enumeration, and what really determines its value?
  • When is an analogical argument a good one?

Treat that list as a self-test: recite each topic's rule from memory before you open its cases.

Provisions

  • Truth and validity in deductive argument, s. Module 1, head 1.4
  • Logic as a formal science, s. Module 1, head 1.2
  • Basic logical concepts: inference and implication, s. Module 1, head 1.4
  • Deductive and inductive reasoning and their use in courts, s. Module 1, head 1.3
  • The laws of thought, s. Module 1, head 1.6
  • Connotation and denotation; positive, negative, contrary and contradictory terms, s. Module 1, head 1.7
  • Induction: simple enumeration as a form of induction, s. Module 1, head 1.8
  • Analogy: characteristics of a good and a bad analogy, s. Module 1, head 1.9

Leading cases

  • Cohen and Nagel
  • Aristotle
  • Bennett and Baylis
  • Keynes
  • Joseph
  • Mill

Exam questions on this unit