Inference Validity
1. **State the problem:** We need to analyze the logical argument about the party shutdown using rules of inference and evaluate its validity.
2. **Identify propositions:**
- Let $P$: The neighbors contacted law enforcement.
- Let $Q$: The volume of the music was excessive.
- Let $R$: The party was shut down.
3. **Given information:**
- Neighbors did not contact law enforcement: $\neg P$.
- Volume was not excessive: $\neg Q$.
- If absence of loud music ($\neg Q$) were sufficient to justify shutdown ($R$), then neighbors would have contacted police ($P$). Symbolically: $\neg Q \to P$.
4. **Logical structure:**
- Premise 1: $\neg P$ (neighbors did not contact police).
- Premise 2: $\neg Q \to P$ (if no loud music, then neighbors contacted police).
5. **Apply Modus Tollens:**
- From $\neg Q \to P$ and $\neg P$, infer $\neg \neg Q$, which simplifies to $Q$.
- This means the volume was excessive.
6. **Conclusion about shutdown:**
- Since $\neg Q \to R$ (absence of loud music justifies shutdown) is given as a conditional, and $\neg Q$ is false (volume was excessive), the condition for shutdown is not met.
- Therefore, the party was not shut down: $\neg R$.
7. **Evaluate validity:**
- The argument uses correct inference rules (Modus Tollens).
- The conclusion $\neg R$ logically follows from the premises.
**Final answer:** The argument is valid; the party was not shut down because the volume was excessive and neighbors did not contact police, consistent with the premises.