Given below are two statements

Statement I: To obvert a proposition, we change its quality and replace the predicate term with its

Statement II: Obversion is valid for any standard form categorical proposition.

In light of the above statements, choose the correct answer from the options given below

The correct option is: Both Statement I and Statement II are true

Let us analyze each statement step-by-step to understand why they are both true:

Analysis of Statement I:
Obversion is a rule of immediate inference in categorical logic. To obvert a categorical proposition, two steps are performed:
1. Change the quality of the proposition (from affirmative to negative, or from negative to affirmative) without changing its quantity.
2. Replace the predicate term with its complement (for example, replacing "humans" with "non-humans").
Thus, Statement I accurately describes the process of obversion.

Analysis of Statement II:
Obversion is a valid immediate inference for all four standard forms of categorical propositions:
- A proposition (All S is P): Obverts to E proposition (No S is non-P), which is logically equivalent.
- E proposition (No S is P): Obverts to A proposition (All S is non-P), which is logically equivalent.
- I proposition (Some S is P): Obverts to O proposition (Some S is not non-P), which is logically equivalent.
- O proposition (Some S is not P): Obverts to I proposition (Some S is non-P), which is logically equivalent.
Because the obverse of any standard-form categorical proposition is logically equivalent to the original proposition, obversion is valid for all of them. Therefore, Statement II is also true.