TLI Chap.10 #27a

[lfmhouse]

My problem syllogism: 1. All mammals breathe oxygen. 2. A horse is a mammal. 3. Therefore, a horse breathes oxygen.
In the answer key, I don't understand the "P" marking for oxygen in the Major premise and the consequent. Is "oxygen" not the direct object. Should the sentence not be changed to its logical form in which case the predicate would be animal (with the predicate-term being "an animal that breathes oxygen"), e.i., Therefore, a horse is an animal(P) that breathes oxygen.
Thank you very much.

[Martin Cothran]

Let's go ahead and put everything in strict logical form:

All mammals(M) are animals that breathe oxygen(P)
All horses(S) are mammals(M)
Therefore, all horses(S) are animals that breathe oxygen(P)

First, the word "oxygen" is only part of the predicate-term "animals that breathe oxygen", which appears in both the major premise and the conclusion. You should not separate it out from the rest of the predicate as if it were a separate term.

Second, the major term (P) is distinguished by the fact that it is the predicate of the conclusion. The predicate of the conclusion is "animals that breathe oxygen". Therefore the major term (P) is "animals that breathe oxygen".

Let me know if that doesn't answer your question.

[lfmhouse]

The answer given in the answer key is what caused my problem. If it had given the answer as you have given in your response to my query, I would not have had a problem with reconciling the key to my answer.