Statements: All cats are mammals. All dogs are mammals. Conclusion: All cats are dogs. This conclusion is
- A. valid
- B. invalid
- C. certainly true
- D. partly true
Explanation
Both groups sit inside mammals, but nothing forces them to overlap each other, so they may be entirely separate as in fact they are. This error, in which the middle term is never distributed, is called the fallacy of the undistributed middle. Sharing a category does not make two groups identical.
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