Fallacy

A fallacy is a flaw in reasoning that leads to invalid, misleading, or unjustified conclusions. Fallacies may appear logical on the surface but fail under critical scrutiny due to errors in argument structure, use of evidence, or assumptions.

• Logical fallacies: Errors in the structure of an argument (e.g., circular reasoning, false dilemma)
• Statistical fallacies: Misuse or misinterpretation of data (e.g., correlation ≠ causation, sampling bias)
• Rhetorical fallacies: Use of persuasive language to obscure weak evidence (e.g., appeal to emotion, authority)

• Sample Size Fallacy
• Overgeneralization
• Publication Bias
• Rhetorical Inflation
• Misuse of p-values or confidence intervals
• Drawing causal inferences from observational data

• Fallacies undermine scientific credibility
• They can mislead readers, clinicians, and policymakers
• Critical appraisal depends on recognizing and avoiding fallacious reasoning

• “This small study showed improvement, so the treatment must be effective.” → Sample Size Fallacy
• “If the drug worked in healthy young men, it will work in elderly women too.” → Overgeneralization
• “It’s published in a top journal, so it must be true.” → Appeal to authority

• Bias
• Critical Appraisal
• Evidence-Based Medicine
• Causality vs. Correlation

• List of Logical Fallacies
• Common Statistical Errors
• Research Integrity and Ethics