Complementary negatives with a subset: Using 'All fish are tortoise' and 'No tortoise is a crocodile', determine whether the conclusions (I) 'No crocodile is a fish' and (II) 'No fish is a crocodile' both follow in standard syllogistic logic.

Given data

• Premise 1: Fish ⊆ Tortoise.
• Premise 2: Tortoise ∩ Crocodile = ∅.
• Conclusions: (I) No Crocodile is a Fish. (II) No Fish is a Crocodile.

Concept/Approach

If Fish are entirely within Tortoise and Tortoise and Crocodile are disjoint, then Fish and Crocodile are also disjoint. 'No S are P' is symmetric, so both formulations are true.

Step-by-step evaluation

Verification

Diagram Fish inside Tortoise; separate Crocodile set disjoint from Tortoise. No overlap with Fish either way; both conclusions stand.

Common pitfalls

• Believing only one of the symmetric 'No' statements holds; both are equivalent.

Final Answer
Both I and II follow.