---
watermark: ORIRO
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name: edu-critical-thinking
provider: ORIRO.ai
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description: >

  Critical thinking — logic, fallacies, argument analysis, evidence evaluation, and reasoning skills.



  Sources: Learning Scientists, OpenStax Education, AAL, CAST, research-based educational practices.
---

# Critical Thinking

## The basics of logic

### Deductive arguments

Premises guarantee the conclusion if valid.
Valid + True premises = Sound argument (conclusion must be true).
**Valid:** "All mammals are warm-blooded. Humans are mammals. Therefore humans are warm-blooded." (Structure guarantees conclusion IF premises true.)
**Invalid:** "Most CEOs are tall. John is tall. Therefore John is a CEO." (Common property doesn't establish membership.)

### Inductive arguments

Premises support (but don't guarantee) the conclusion.
Strong inductive: "Every crow ever observed has been black. Therefore the next crow observed will probably be black." (Could be wrong — but evidence is strong.)
Inductive arguments are evaluated by strength and cogency, not validity.

## Common logical fallacies

**Ad hominem:** Attack the person, not the argument.
"We shouldn't take his climate research seriously — he drives an SUV."
Counter: Assess the argument on its merits regardless of the source.

**Straw man:** Misrepresent the opponent's argument to make it easier to attack.
"You said we should have fewer restrictions" → "So you want total anarchy?"
Counter: Steelman — engage with the strongest version of their argument, not the weakest.

**False dichotomy:** Present only two options when more exist.
"You're either with us or against us."
Counter: What's the full range of options?

**Appeal to authority:** Cite an expert as if their word settles the debate.
Experts can be wrong. Their authority is evidence, not proof. (Weight proportional to expertise on the specific question.)
Counter: What does the evidence say? Is this expert speaking within their domain of expertise?

**Slippery slope:** Claim one step inevitably leads to extreme outcomes without justification.
"If we allow X, next we'll have Y, then Z." (Requires evidence for each causal step.)

**Correlation ≠ causation:** Observed association does not establish that one thing causes another.
The rooster crows before sunrise — the rooster doesn't cause sunrise.

**Confirmation bias:** Seek evidence that confirms rather than tests your belief.
Counter: Actively seek disconfirming evidence. Ask: "What would change my mind?"

**Begging the question:** Conclusion is assumed in the premise.
"God exists because the Bible says so, and the Bible is true because God wrote it."

**Hasty generalization:** Draw broad conclusions from too few examples.
"Two people from X country were rude to me. People from X are rude."

**Appeal to nature:** Natural = good, artificial = bad.
Natural: arsenic, mercury, cyanide. Artificial: penicillin, vaccines, clean water.

## Evaluating sources

**SIFT method:**
S — Stop: Don't share or trust immediately.
I — Investigate the source: Who is making this claim? What's their expertise and motivation?
F — Find better coverage: What do other sources say?
T — Trace claims: Go upstream to the original source. Does the original support the claim?

**Red flags:** Emotionally charged headlines, appeals to fear/outrage, no author, no date, no sources cited, domain mimicking reputable sources (ABCnews.com.co vs. ABCnews.com).

## Reasoning under uncertainty

**Base rates matter.** The prior probability before new evidence.
**Calibration:** Hold beliefs proportional to evidence.
"I believe this is true" should mean something. Reserve "I'm certain" for things you'd bet your life on.
**Update your beliefs when evidence changes.** Consistency with your past self is not a virtue if the evidence has changed.

Sources: OpenStax Introduction to Logic (CC-BY), SIFT media literacy (mikecaulfield.com), Thinking Fast and Slow (Kahneman — principles), Foundation for Critical Thinking (criticalthinking.org — free resources)