Bias & Logical Fallacies
- Distinguish bias in a source from bias in your own reasoning
- Identify common logical fallacies in arguments
- Explain how confirmation bias distorts research and how to counter it
Two kinds of bias
Bias comes in two forms, and both matter. Bias in a source is a slant in the material — one-sided evidence, loaded language, a hidden vested interest. Bias in your own thinking is a slant in how you gather and interpret information. The most dangerous is confirmation bias: the tendency to seek, believe, and remember only what fits what you already think, while dismissing what does not. A source’s bias you can flag; your own bias you must actively fight, because it is invisible from the inside.
A field guide to fallacies
A logical fallacy is a flaw in reasoning that makes an argument invalid even when it sounds persuasive. Common ones: ad hominem (attacking the person, not the argument); straw man (refuting a distorted version of the opposing view); false dilemma (presenting only two options when more exist); slippery slope (claiming one step must lead to an extreme outcome without justification); hasty generalization (drawing a broad conclusion from too little evidence); appeal to authority (treating a famous name as proof, especially outside their expertise); and post hoc (assuming that because B followed A, A caused B). Naming a fallacy is a precise way to say why an argument fails.
Countering your own bias
You cannot eliminate confirmation bias, but you can build habits that check it. Actively seek disconfirming evidence — search for the strongest case against your view. Steelman opposing arguments before critiquing them. Ask what would change your mind, and notice if the honest answer is "nothing." Separate evidence-gathering from conclusion-forming, so you are not screening sources for agreement. These are not signs of a weak position; they are what make a conclusion trustworthy to a skeptical reader.
Identify the logical fallacy in each: (a) "Dr. Lee opposes the bridge project, but she drives an expensive car, so ignore her." (b) "Either we cut the arts program or the school goes bankrupt." (c) "After the new principal arrived, test scores rose, so the principal caused the improvement."
- 1.For (a), the argument attacks Dr. Lee’s character/wealth instead of engaging her reasons — this is ad hominem.
- 2.For (b), only two options are offered when many exist (partial cuts, new funding, other savings) — this is a false dilemma.
- 3.For (c), one event followed another and is assumed to have caused it, ignoring other factors — this is post hoc (false cause).
- 4.In each case, name the fallacy and note that the conclusion might still be true; the point is that this reasoning does not establish it.
A debater responds to an opponent’s climate proposal by saying, "You failed science class, so your plan is worthless." Which fallacy is this?
The bias hardest to catch is your own. If every source you gathered happens to support your first hunch, that is a red flag, not a victory — you may be screening for agreement. Go find the strongest source that disagrees with you.
Which research habit most directly counters confirmation bias?
On the exam, precisely naming a flaw ("this commits a false dilemma") is stronger evidence of critical analysis than vaguely calling an argument "weak." A correctly identified fallacy is a concrete, rubric-worthy critique.
Answer the 2 checkpoints as you read.
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