How do linguists define the idea of a grammatical subject?

Question

How do linguists define the idea of a grammatical subject?

The only place I could find on the Internet about linguists' definition of a grammatical subject was at the SIL glossary, here. (http://www-01.sil.org/linguistics/GlossaryOflinguisticTerms/WhatIsASubject.htm).

According to this definition, grammatical subjects often have...

• "The grammatical characteristics of the agent of typically transitive verbs"
• "The grammatical characteristics of the single argument of intransitive verbs"
• "A particular case marking or clause position"
• "The conditioning of an agreement affix on the verb"
• "The capability of being obligatorily or optionally deleted in certain grammatical constructions, such as the following clauses: Adverbial, Complement, Coordinate"
• "The conditioning of same subject markers and different subject markers in switch-reference systems"
• "The capability of co-reference with reflexive pronouns"

The definition doesn't imply that all grammatical subjects in all languages have all of these characteristics.

But I was wondering whether this definition passes muster among the professional linguists on this list. If not, is there are better source of information about what grammatical subjects are?

Answer 1

Notice that the glossary say subjects often have these characteristics.
I.e, the characteristics are common, but not definitive.

In fact, there is no universal characteristic "Subject", except insofar as it may be demanded by various theories of grammar. In English, the concept of "subject" is very well-defined in most cases, but there are a few marginal situations where it's not so obvious, for instance with dummy-insertion rules like There-Insertion and Extraposition

• There are two unicorns in the garden. (the verb agrees with unicorns)
  but

• There appear to be two unicorns in the garden. (there undergoes Subject-Raising)

• It was unfortunate that he vomited during his aria. (That-clause subject or It subject?)

But in other languages the concept of Subject may be nonexistent, because it depends on a particular orientation of grammatical relations that doesn't occur everywhere.

What English (and Indo-European languages generally) mean by Subject is a relation between some noun phrase in a clause and the verb of that clause. In English, every clause has a Subject. We contrast the Subject with the Direct Object, which is specially marked in many languages (this is the "accusative case", of which English has only a few remnants like him and them), and which occurs along with the Subject, but only in some clauses; we call these clauses Transitive.

So every English clause has a Subject, but Direct Objects only occur in some clauses.
This is called an "Accusative" system. There are other systems.

One such system is the "Ergative" system, which is common in Mayan languages, Australian languages, Caucasian languages, and many others. In an Ergative system every clause has one kind of noun phrase (called an "Absolutive") and some clauses (the transitive ones) also have a specially-marked noun phrase (called an "Ergative") as well as an Absolutive. Not much different, except that the Ergative noun phrase in a transitive clause is what English would call the "subject", and the Absolutive is the "object".

This is very confusing for those who don't realize that there are other ways of marking NPS.
There's a diagram of the differences here.

Answer 2

Yes, you are right, in traditional linguistics that is, linguistics before generative grammar, the idea "subject" is not well-defined, so every definition given by the traditional linguist can not cover all the cases.

So, generative grammar does not use it in the traditional sense, and gives a definition relating D-Structure. You may see some general works of generative grammar for the definition.