Answer :
Answer:
Conversion, obversion, and contraposition are all logical operations used in traditional categorical logic to transform propositions. These operations apply to standard form categorical propositions (A, E, I, O statements). Here’s a detailed look at their differences and similarities:
### Conversion
**Definition:** Conversion involves swapping the subject and predicate of a categorical proposition.
- **Applies to:** E (No S are P) and I (Some S are P) statements without changing their truth value.
- **Example:**
- Original: "No cats are dogs." (E)
- Converted: "No dogs are cats." (E)
- Original: "Some cats are pets." (I)
- Converted: "Some pets are cats." (I)
### Obversion
**Definition:** Obversion involves changing the quality of the proposition (from affirmative to negative or vice versa) and replacing the predicate with its complement.
- **Applies to:** All four types (A, E, I, O).
- **Steps:**
1. Change the quality (affirmative to negative or negative to affirmative).
2. Replace the predicate with its complement (non-P for P).
- **Example:**
- Original: "All cats are animals." (A)
- Obverted: "No cats are non-animals." (E)
- Original: "Some dogs are not friendly." (O)
- Obverted: "Some dogs are non-friendly." (I)
### Contraposition
**Definition:** Contraposition involves replacing the subject with the complement of the predicate and the predicate with the complement of the subject.
- **Applies to:** A (All S are P) and O (Some S are not P) statements without changing their truth value.
- **Steps:**
1. Replace the subject with the complement of the predicate.
2. Replace the predicate with the complement of the subject.
- **Example:**
- Original: "All cats are animals." (A)
- Contrapositive: "All non-animals are non-cats." (A)
- Original: "Some cats are not friendly." (O)
- Contrapositive: "Some non-friendly things are not non-cats." (O)
### Similarities
1. **All are transformations of categorical propositions:** They each transform propositions in different ways to explore logical relationships.
2. **Maintain logical equivalence (in applicable cases):** They preserve the truth value of the original statement in specific cases.
### Differences
1. **Operation:**
- **Conversion** swaps subject and predicate.
- **Obversion** changes the quality and complements the predicate.
- **Contraposition** complements both subject and predicate and swaps them.
2. **Applicability:**
- **Conversion** is valid for E and I statements.
- **Obversion** is valid for A, E, I, O statements.
- **Contraposition** is valid for A and O statements.
### Summary Table
| Operation | Transformation | Valid for | Example |
|-----------------|-------------------------|-----------------|--------------------------|
| Conversion | Swap S and P | E, I | E: "No S are P" → "No P are S" |
| | | | I: "Some S are P" → "Some P are S" |
| Obversion | Change quality, | A, E, I, O | A: "All S are P" → "No S are non-P" |
| | complement predicate | | O: "Some S are not P" → "Some S are non-P" |
| Contraposition | Complement S and P, | A, O | A: "All S are P" → "All non-P are non-S" |
| | then swap | | O: "Some S are not P" → "Some non-P are not non-S" |
Understanding these operations is crucial for mastering traditional logic and categorical syllogisms.
