Truth Table Validity
1. **State the problem:** We want to verify the logical argument: "If a number is even, then it is divisible by 2. The number is not divisible by 2. Therefore, the number is not even." using a truth table.
2. **Identify propositions:** Let $p$ = "The number is even" and $q$ = "The number is divisible by 2".
3. **Logical form:** The statement is $p \to q$. The argument is:
- Premise 1: $p \to q$
- Premise 2: $\neg q$
- Conclusion: $\therefore \neg p$
4. **Truth table setup:** We list all possible truth values for $p$ and $q$, then evaluate $p \to q$, $\neg q$, and $\neg p$.
| $p$ | $q$ | $p \to q$ | $\neg q$ | $\neg p$ |
|-----|-----|-----------|----------|----------|
| T | T | T | F | F |
| T | F | F | T | F |
| F | T | T | F | T |
| F | F | T | T | T |
5. **Check validity:** The argument is valid if whenever $p \to q$ is true and $\neg q$ is true, then $\neg p$ is also true.
6. **Analyze rows where $p \to q$ and $\neg q$ are true:**
- Row 2: $p \to q$ is F, so ignore.
- Row 4: $p \to q$ is T, $\neg q$ is T, and $\neg p$ is T.
7. **Conclusion:** In all cases where the premises are true, the conclusion is true. Therefore, the argument is logically valid.
**Final answer:** The argument "If a number is even, then it is divisible by 2. The number is not divisible by 2. Therefore, the number is not even." is valid by truth table analysis.