Exercise · ZW-RULE-OF-INFERENCE-009 · ★★★ Advanced
Which of these options is a valid rule of inference that obtains \(\psi\) from \(\varphi \to \psi\) and \(\varphi\)?
Choose one option.
Show answer
- A. Modus ponens
Explanation
Modus ponens obtains \(\psi\) from \(\varphi \to \psi\) and \(\varphi\); affirming the consequent is a fallacy and changing a symbol is not a rule.
Review the concept: Rule of inference
A rule of inference authorizes the formal step from the premises \(\varphi_1,\ldots,\varphi_n\) to the conclusion \(\psi\).
\[\frac{\varphi_1,\ldots,\varphi_n}{\psi}\]
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