A useful sequence for diagnosing apparent proofs is:
1. Matter: What is each premise, and why should it be accepted?
2. Meaning: Do key terms preserve the same senses and relevant features?
3. Form: Even granting the premises, does the conclusion necessarily follow?
For example: “Everything visible exists; therefore everything that exists is visible.” The converse is not established. If A, then B does not automatically give if B, then A.
Separate an unwarranted universal claim from an illicit reversal, since they are distinct errors.