Opinion Science #112: Thinking Categorically with Greg Murphy
17 snips
Jan 5, 2026 
Greg Murphy, an emeritus professor and cognitive psychologist renowned for his work on categorization, dives into the fascinating world of how we classify concepts. He explores the impact of categories on our social perceptions and judgments, emphasizing their role in guiding expectations and potentially fostering prejudice. Murphy also discusses the flexibility of categorization, how individual knowledge can challenge broad categories, and debates the distinction between real and invented classifications. The conversation highlights the significance of language in shaping our understanding.
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Purple Tomatoes Upset Expectations
- Greg Murphy recounts finding purple (black) tomatoes in his garden and how it challenged his tomato stereotype.
- He notes most categorizations revert because categories are usually useful despite rare exceptions.
What Makes A Category Useful
- A category groups entities that share significant properties and guide similar treatment.
- Good categories convey useful predictions about members' properties and uses.
Use Rich Category Labels Intentionally
- Use language to access richer categories when you need useful predictions.
- Rely on specific category names rather than minimal properties to guide action.
