Logic for Lawyers Exam 1

Argument

Some number of premises put forward in favor of a conclusion

Premise

Support or justification offered for a conclusion

Conclusion

The claim an argument tries to show true

Implicit premise

An unstated premise the arguer likely has in mind, or that links the premises to the conclusion

Independent premises

Premises that each support the conclusion on their own

Dependent premises

Premises that support a conclusion only by working together

Subconclusion

An intermediate conclusion that also serves as a premise

Standard form

Numbered premises, an inference bar, and a conclusion marked C

Extraneous information

Information that is irrelevant to the argument

Deductive argument

An argument that tries to guarantee its conclusion

Inductive argument

An argument that tries to show its conclusion is probable

Abductive argument

Argues that a hypothesis is the best explanation of the evidence. The slides use the same terms as inductive: strong, weak, and cogent.

Valid

A logical deductive argument whose premises, if true, would guarantee its conclusion

Invalid

A deductive argument whose premises do not guarantee its conclusion

Sound

A valid argument with all true premises

Unsound

Either invalid or containing a false premise

Strong

An inductive or abductive argument with a greater than point five chance of a true conclusion given true premises

Weak

An inductive or abductive argument that is not strong

Cogent

A strong inductive or abductive argument with all true premises

Rational persuasiveness

Valid, or strong, reasoning, plus reasonable premises, plus for inductive arguments no defeater

Defeater

Information that undermines an otherwise strong argument

Modus ponens

Valid form: if P then Q; P; therefore Q

Affirming the consequent

Invalid form: if P then Q; Q; therefore P

Denying the antecedent

Invalid form: if P then Q; not P; therefore not Q

Counterexample

scenario showing a claim false, a definition inadequate, or an argument's reasoning flawed

Reductio ad absurdum

Rejecting a claim by showing it leads to an absurd or unacceptable result

Vague

Having borderline cases

Ambiguous

Having two or more distinct meanings

Issue

A yes or no question arising from a legal dispute, on which parties disagree

Holding

A tribunal's resolution of an issue

Finding

A determination about facts

Tribunal

Any person or institution the parties ask to resolve a dispute

Level of abstraction

The scope of an issue and its resolution: how many persons and situations it covers

Application of law to fact

Determining the legal consequences of the facts

Adjudicative fact

A low level fact about the parties to a particular dispute

Legislative fact

A high level, general fact used in making law

Judicial notice

A tribunal finding an indisputable fact without evidence from the parties

Authority

The law a tribunal uses to decide an issue: a text, a precedent, or public policy

Rule of law

Legally significant facts, the legal consequences, and sometimes excuses

Affirmative defense

An excuse that defeats liability even when the other elements of a rule are met

Case at bar

The case now before the tribunal

Precedent

A tribunal's previous resolution of an analogous dispute

Rationale

The reasons the facts of a precedent led to its outcome

Distinction

A difference in facts between a precedent and the case at bar, plus an explanation of why it is legally significant

Disanalogy

A preemptive distinction of a precedent the adversary has not invoked

Dictum

Commentary in a court opinion beyond what is needed to decide the case

Stare decisis

Standing by prior decisions, so a decided issue governs later cases