Unit One Essentials: Arguments & Non-Arguments

Logic & Critical Thinking

• Logic = organised study that evaluates arguments; focus is on assessing correctness of reasoning.
• Critical thinking = disciplined process of analysing, synthesising and evaluating information by rational standards.
• Significance: sharpens reasoning, makes rules of inference explicit, distinguishes good from bad reasoning, strengthens performance across disciplines, adds intellectual enjoyment.

Core Skills for Critical Thinking

• Analytical – break issues into comprehensible parts.
• Interpretative – explain meanings clearly.
• Inferential – draw sound conclusions from evidence.
• Evaluative – judge credibility, relevance, detect fallacies.
• Explanative – state reasons succinctly and coherently.
• Problem–solving – devise effective strategies.
• Creative – think beyond standard methods when needed.

Basic Terms: Premises, Propositions, Statements

• Premise: proposition offered as evidence for a conclusion; must carry a truth-value.
  • Forms: simple / compound; particular / general; explicit / implicit.
• Proposition: declarative content that can be assigned true or false.
• Statement: any sentence; only those with truth-value count as propositions.
  • Not propositions: questions, commands, suggestions, exclamations, purely subjective value claims.

Inference & Conclusion

• Inference = reasoning process that links premises to conclusion.
• Conclusion = claim that premises are intended to support.
  • May be explicit or implicit; may appear at beginning, middle or end.
• Inference indicators:
  • Premise indicators – because, since, assuming that, inasmuch as, seeing that, the reason is that.
  • Conclusion indicators – therefore, thus, hence, so, consequently, which shows that.

Arguments in Logic

• Logical argument = sequence of propositions in which premises purport to justify a conclusion.
• Ordinary dispute ≠ logical argument; the latter requires inferential structure.
• Standard form: list premises, draw horizontal line, place conclusion beneath.
• Recognising arguments:
  • Locate a claim being proved.
  • Use partial test – insert “therefore” between sentences; if sense emerges, likely an argument.
  • Check for indicator words but verify their role.

Analysing Arguments: Good vs Bad

• Deductive argument good (sound) when:
  • Form is valid (impossible for true premises to yield false conclusion).
  • All premises are true.
• Inductive argument good (cogent) when:
  • Premises make conclusion highly probable.
  • Premises are in fact true.
• Bad arguments:
  • Deductive – invalid form, or valid with at least one false premise.
  • Inductive – weak link from premises to conclusion, or contains false premises.

Non-Arguments in Logic

Passages without an inferential claim.

• Warning / Advice – caution or recommendation only.
• Statement of belief or opinion – expresses view without proof.
• Report – conveys information about events.
• Loosely associated statements – related topic, no logical linkage.
• Expository passage – explains a topic sentence; only becomes argument if explanations are meant as proof.
• Illustration – gives examples; becomes argument from example only when examples aim to establish a claim.
• Explanation – distinguishes explanandum from explanans; clarifies rather than proves.
• Single conditional statement – “if … then …” alone is not an argument; needs additional premise affirming or denying one part to yield inference.