I think what you're missing is how our analysis of grammar and logic evolved historically.
It is based on notions introduced by Aristotle.
To quote - following Wikipedia - the Internet Encyclopaedia of Philosophy:
Aristotelian logic identifies a categorical proposition as a sentence
which affirms or denies a predicate of a subject, optionally with the
help of a copula. An Aristotelian proposition may take the form of
"All men are mortal" or "Socrates is a man." In the first example, the
subject is "men", predicate is "mortal" and copula is "are", while in
the second example, the subject is "Socrates", the predicate is "a
man" and copula is "is".
So a subject is called that because it is being subjected to an assertion.
(Aristotle wrote in Greek, while proposition, predicate, subject and copula are Latin words, so they must be later translations.)
The same analysis can be extended to all other indicative sentences (this is standard practice in traditional grammar):
- Socrates (subject) died (predicate)
- Socrates (subject) was cold (predicate)
- Socrates (subject) went cold (predicate)
- Socrates (subject) faced the death penalty (predicate)
- Socrates (subject) drank the conium (predicate)
- Aristophanes (subject) mocked Socrates (predicate)
- The death penalty (subject) was imposed on Socrates (predicate)
- It (subject) rains (predicate)
Here, predicates can also describe processes, events, or actions.
The subject is still what the predicate is about. In some cases (such as 8), the subject is purely formal.
In many cases (4-7 here), the verb being used is not a copula, and requires the presence of one or more additional noun phrases, which are then called objects.
Now to your question. A subject is something that undergoes something; for sentences that describe an action with an object, it is the object, not the subject of the sentence, that undergoes the action; therefore, wouldn't it be more logical to apply the term subject to the object instead?
For instance, in Socrates drank the conium (3), the conium is subjected to being drunk, but Socrates is not really subjected to drinking the conium - the sentence describes him as taking an active role, rather than passively undergoing the action.
I think you're absolutely correct that this is the case for most sentences that describe actions with subjects and objects. What you've missed:
- The term subject is not limited to that type of sentence, but is applied to all sentences that express an assertion.
- It is not intended to describe the subject of an action, but the subject of the assertion the sentence makes - regardless of whether that assertion concerns an action.
- When it does, the subject of the assertion is still the subject of the sentence, even when the subject of the action being described is the object of the sentence. Socrates drank the conium is an assertion about Socrates, not (so much) about the conium.
- Subjects, propositions and predicates were introduced with the purpose of describing assertions, not actions; objects were later added when predicates were analysed in more detail; this terminology then became standard for describing the structure (grammar) of our languages, and that is their context of use. This terminology long predates the logical description of actions and events, which only took off in the 20th century.
Your question really is not so much a question of philosophy as it is a question of language. Greek and English happen to treat Socrates in Socrates is a man and Socrates mocks Aristophanes much the same way. This gives rise to a term subject that is applied to Socrates in both cases.
In an ergative language, subjects of intransitive sentences such as Socrates is a man are treated much more like the objects of transitive sentences. If our terminology had been developed by philosophers speaking ergative languages, the term subject might have been used in the way you propose.