✍️ Writing & Copywriting

Fallacy Finder

📁 Writing & Copywriting 👤 Contributed by @devisasari 🗓️ Updated 2026-04-19

The prompt

I want you to act as a fallacy finder. You will be on the lookout for invalid arguments so you can call out any logical errors or inconsistencies that may be present in statements and discourse. Your job is to provide evidence-based feedback and point out any fallacies, faulty reasoning, false assumptions, or incorrect conclusions which may have been overlooked by the speaker or writer. My first suggestion request is "This shampoo is excellent because Cristiano Ronaldo used it in the advertisement."

0 copies

🚀 Open in ChatGPT ✨ Open in Claude 💎 Open in Gemini

Example outputs

Here is what ChatGPT, Claude, and Gemini typically return for this prompt:

🚀 ChatGPT

This argument commits the "Appeal to Authority" fallacy, specifically a variant called "Appeal to Inappropriate Authority." Cristiano Ronaldo is an expert in football, not in chemistry or hair care products. His endorsement doesn't provide evidence about the shampoo's quality or effectiveness. The product should be evaluated based on its ingredients, scientific testing, and verified customer reviews rather than celebrity endorsement.

✨ Claude

This is a classic example of the "Appeal to Celebrity" fallacy (a specific type of appeal to authority). Ronaldo's expertise lies in football, not cosmetic chemistry or dermatology. His use of the product in an advertisement—likely a paid endorsement—provides no actual evidence about the shampoo's effectiveness. We'd need to examine ingredient quality, clinical trials, or independent reviews to assess whether it's truly excellent.

💎 Gemini

This commits the appeal to authority fallacy. Cristiano Ronaldo's athletic expertise doesn't qualify him to evaluate shampoo quality. Celebrity endorsements are marketing strategies, not evidence of product efficacy. The shampoo's excellence should be determined by factors like ingredient analysis, dermatological testing, and consumer performance data, not by who appears in its advertisements.

How to use this prompt

Copy the prompt above or click an "Open in" button to launch it directly in your preferred AI. You can then customize the wording to match your exact use case — for example replacing placeholders like [your topic] with real context.

Which AI model works best

Claude is widely considered the strongest writing model in 2026 — more nuanced voice, better ear for rhythm, fewer clichés. ChatGPT is faster and more format-flexible. Gemini is useful when you need to pull from long reference documents.

How to customize this prompt

Specify the target audience, word count, and tone explicitly. Good additions: "Write in the style of [author or publication]", "Avoid these words: [list]", "The reader is [specific profile]". Paste any reference material or brand voice guide after the prompt.

Common use cases

Turning a rough outline into a polished blog post
Rewriting bulk content (product descriptions, email campaigns)
Ghostwriting social media threads in a founder's voice
Copy-editing long-form drafts for flow and clarity
Drafting press releases from a factual brief

Variations

Adapt the tone (more casual, more technical), change the output format (bullet points vs. paragraphs), or add constraints (word limits, target audience).