PHIL 109: Inductive & Deductive Arguments Vocabulary Flashcards

Overview of Inductive vs. Deductive Arguments

• Fundamental Distinctions:

  • Deductive Reasoning: Associated with necessity (MUST), aiming to provide certainty and guarantee the conclusion.

  • Inductive Reasoning: Associated with likelihood (PROBABLY), aiming to establish probability and provide strong supporting evidence.

Core Differences Between Deductive and Inductive Arguments

• Primary Intent / Objective:

  • Deductive Argument: Tries to guarantee the conclusion.

  • Inductive Argument: Tries to make the conclusion probable.

• Truth Relationship (If Premises Are True):

  • Deductive Argument: The conclusion MUST be true.

  • Inductive Argument: The conclusion is PROBABLY true.

• Central Focus / Main Idea:

  • Deductive Argument: Certainty.

  • Inductive Argument: Probability.

• Evaluation Standard:

  • Deductive Argument: Judged as Valid or Invalid.

  • Inductive Argument: Judged as Strong or Weak.

• Best Possible Qualification (Best Type):

  • Deductive Argument: Sound.

  • Inductive Argument: Cogent.

• Formula for the Best Type:

  • Deductive Argument (Sound Formula):     $\text{Sound} = \text{Valid} + \text{True Premises}$

  • Inductive Argument (Cogent Formula):     $\text{Cogent} = \text{Strong} + \text{True Premises}$

Deductive Arguments

• Definition: An argument structure where the premises are intended to guarantee the conclusion with absolute certainty.

• Evaluation Criteria and Terms:

  • Valid: The logical structure is sound. If the premises were true, the conclusion would necessarily have to be true.

  • Invalid: The conclusion does not necessarily follow from the premises, even if the premises are assumed true.

  • Sound: The argument is valid AND all of its premises are actually true.

  • Unsound: The argument is invalid, or at least one of its premises is actually false.

• Standard Deductive Example:

  • Premise 1: All dogs are mammals.

  • Premise 2: Poodles are dogs.

  • Conclusion: Therefore, poodles are mammals.

  • Interpretation: If the two premises are true, it is impossible for the conclusion to be false. That strict logical necessity defines the argument as deductive.

• Common Deductive Forms:

  • Conditional Form (IF … THEN):

  • Premise 1: If Joe cheats, then Joe fails.

  • Premise 2: Joe cheated.

  • Conclusion: Therefore, Joe failed.

  • Disjunctive Form (EITHER … OR):

  • Premise 1: Either Maya is in class or at home.

  • Premise 2: Maya is not at home.

  • Conclusion: Therefore, Maya is in class.

  • Categorical Form (ALL / NO / SOME):

  • Premise 1: All freshmen are college students.

  • Premise 2: Mia is a freshman.

  • Conclusion: Therefore, Mia is a college student.

Inductive Arguments

• Definition: An argument structure where the premises are intended to make the conclusion probable, rather than logically guaranteed.

• Evaluation Criteria and Terms:

  • Strong: An inductive argument in which the premises render the conclusion highly probable by providing solid support.

  • Weak: An inductive argument in which the premises provide little to no support for the conclusion.

  • Cogent: The argument is strong AND all of its premises are actually true.

  • Uncogent: The argument is weak, or at least one of its premises is actually false.

• Standard Inductive Example:

  • Premise 1: $95\%$ of students in the class passed the exam.

  • Premise 2: Maya is a student in that class.

  • Conclusion: Therefore, Maya probably passed the exam.

  • Interpretation: Maya could still be part of the $5\%$ who failed. The evidence makes the conclusion highly likely, but not strictly guaranteed.

• Argument from Analogy:

  • Definition: An inductive argument that compares two or more entities and reasons that because they share specific known similarities, they likely share another property as well.

  • Common Clue Words: "similarly", "likewise".PREFIX

  • Example Scenario:

  • Premise 1: My previous Toyota Camry was reliable.

  • Premise 2: My friend has a very similar Camry.

  • Conclusion: Therefore, her car will probably be reliable too.

Two-Step Identification Method

• Step 1: Assume that every premise in the argument is completely true.

• Step 2: Ask the central diagnostic question: "Could the conclusion STILL be false?"

  • If NO: The argument is Deductive.

  • If YES (but the evidence makes it likely): The argument is Inductive.

Comparing Deductive vs. Inductive Arguments on the Same Topic

• Deductive Reasoning Framing:

  • Premise 1: All freshmen must take ENG 101.

  • Premise 2: Jay is a freshman.

  • Conclusion: Therefore, Jay must take ENG 101.

  • Key Indicator: MUST $\rightarrow$ Deductive.

• Inductive Reasoning Framing:

  • Premise 1: Most freshmen take ENG 101.

  • Premise 2: Jay is a freshman.

  • Conclusion: Therefore, Jay probably takes ENG 101.

  • Key Indicator: PROBABLY $\rightarrow$ Inductive.

Flashcard Bank Definitions

• Deductive Argument: Premises are intended to guarantee the conclusion.

• Inductive Argument: Premises are intended to make the conclusion probable.

• Valid: A deductive argument whose conclusion logically follows from its premises.

• Sound: A valid deductive argument with true premises.

• Strong: An inductive argument whose premises give good support to the conclusion.

• Cogent: A strong inductive argument with true premises.

• Certainty: The kind of support deductive arguments aim to provide.

• Probability: The kind of support inductive arguments aim to provide.

One-Line Memory Check

• Deductive Formula:   $\text{Deductive} = \text{MUST} = \text{Valid / Sound}$

• Inductive Formula:   $\text{Inductive} = \text{PROBABLY} = \text{Strong / Cogent}$