I'm no linguist and I'm unaware of the recent development in linguistics, let alone all the past developments, but I know some of the past developments at the very least, so I'm asking this question to anyone who is well versed in the current linguistic development. (So if you're not familiar with the recent development, please don't bother to downvote this post or answer my question simply because it doesn't make sense to your traditional linguistic knowledge. Not that I really care about this post being downvoted or even being cluttered with boring answers, but that I'd really like to know if there's anyone out there who can think outside the box without getting carried away with the box itself.)


As far as I know, there is a well-known distinction between a grammatical subject and a logical subject. The former concerns syntax, the latter semantics. The two subjects sometimes are the same as in:

I have no idea.

Here, both the subjects are "I" and no other.

But sometimes, depending on whether we want the former or the latter, we might get a different subject in the same sentence. Please see the following dialogue between A and B:

A: There is chaos.

B: That I know.

In A's line, the grammatical subject is "There", as shown in a counterpart interrogative "Is there chaos?" (the subject-auxiliary inversion), whereas the logical subject is "chaos" because A is not talking about "there" but "chaos".

Now moving on to B's line, both the grammatical and logical subject are "I" under the traditional definition of these terms. And they say that "That" is the object of the verb "know" and it is simply placed in front of the subject "I". Right? (If this is not what is normally accepted, please let me know.)


Is there any new development in linguistics that considers "That" in B's line the subject, be it the grammatical subject or the logical subject or some new kind of subject? Because, syntactically, "That" occupies the position of the subject, and semantically "That" is essentially what B is talking about.


Oxford Dictionaries Online has this definition for "subject":

Grammar A noun or noun phrase functioning as one of the main components of a clause, being the element about which the rest of the clause is predicated.

Applying this definition to B's sentence, "That" can be considered "a noun functioning one of the main components of a clause", and the rest of the clause "I know" predicated about "That".

  • 2
    It's probably not a good idea to talk about about logical subjects - topic would be less confusing.
    – curiousdannii
    Sep 7, 2015 at 10:57
  • 1
    There's more than position involved, and there's nothing intrinsically wrong with using the term "Logical Subject", though it conflates a number of cases, and doesn't apply in the (B) case anyway. I still use it in talking about derivations which go from Logical Structure to Surface Structure. Strictly speaking, LS doesn't have "subjects"; it does have case relations, generally determined by the predicates and constructions chosen, and Agent is the prototype case for Subject with active predicates, for instance, so often these can be read off easily enough. And change during derivations.
    – jlawler
    Sep 7, 2015 at 15:07
  • 3
    I haven't come across people using "subject" for semantics. They usually use a different set of labels for semantic roles. See en.wikipedia.org/wiki/Thematic_relation
    – prash
    Sep 7, 2015 at 22:02
  • @prash: Really? Have you not heard of the logical subject? If not, see the first one (a Merriam-Webster link for a subject being used for semantics): google.com/?gws_rd=ssl#q=%22logical+subject%22
    – JK2
    Sep 8, 2015 at 4:18
  • 2
    It's quite likely falling into disuse now. This book calls it a historical term.
    – prash
    Sep 8, 2015 at 11:29

3 Answers 3


No, there is no theory I know of that considers the "that" in "That I know" to be a subject. And I don't know of any reason to think it is a subject. If you know of any subject-like grammatical properties of such a topic/focus, please tell us what they are. Then maybe you could get some constructive comments.

  • In B's line, "That" is the topic of B's talk and that's why the sentence starts with "That". So, here's a topic word and that topic word is at the beginning of the sentence. Isn't this what the "subject" is all about? I mean, when you think about the etymological meaning of the word "subject".
    – JK2
    Sep 7, 2015 at 23:10
  • 1
    True, but the etymological meaning is not the grammatical meaning. The subject of a clause has a whole list of properties that can be tested, but the "subject" being discussed is not a single word and is very vague; no help at all. There's a specific rule (called Topicalization) that generates sentences like B from sentences like I know that. The grammar doesn't require any further explanation. But the pragmatics does; topicalization always carries some kind of emphasis.
    – jlawler
    Sep 8, 2015 at 21:07
  • @jlawler: Thank you very much! "Topicalization" might be the answer I've been looking for. Do you happen to know of any book, paper, link or anything on that subject that you recommend reading? I'd really appreciate it.
    – JK2
    Sep 9, 2015 at 4:19
  • 1
    Careful about that term "topicalization". The constituent brought to the front by the transformation ordinarily called topicalization isn't necessarily a topic. As I understand the literature on this, it might better be called a "focus". I do think there is some natural relationship between subject and topic, but I doubt there is between subject and focus. Here is a discussion from an expert on the subject: sfu.ca/~hedberg/gundel-fretheim.pdf.
    – Greg Lee
    Sep 9, 2015 at 7:26
  • 1
    Oh, I don't know. Maybe it's the focus. I don't see much value in just giving things names.
    – Greg Lee
    Sep 10, 2015 at 4:03

In this instance, in this sentence: "That I know". "That" is just a direct object, the subject is unambiguously "I". Both the logical and syntactical subject.


The subject in Example-A is "chaos" and in Example-B is "I". In the first example there is inversion of verb and subject because of introductory adverb "There". In the second example, the object "That" is positioned first to give it emphasis while the subject "I" is still placed before the verb "know" and doer of the action denoted by the verb "know". In both the cases, the subject is both logical and grammatical. The divergence, however, appears when a sentence is in passive voice, where the logical subject or the doer of the action is not the grammatical( or, positional) subject; and the grammatical subject actually receives the action denoted by the verb.

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