On the syntax of "just" with a "that-clause."

There is a pragmatic use of "just" in utterances such as "It's just that" as a discourse marker to deflect a counterargument. It's used in the same way as what is explained in the summary of the article below about entitled "I'm just saying" [that]. This usage should be analyzed as pragmatics or discourse analysis. The grammar of this form is dictated by the speaker's strategy but the clause precedes an argument that will be presented after it in another clause or refer back to it.

It can take the forms such as: "It's just that", [etc.] or it can be associated with a verb, "She just thinks that" or "I'm just saying that".

1 - It's just that they won.

just that [rest of clause] means there has been a discussion of some kind previously:

Imagine a conversation where someone says, about a football team:

A: They did not play really well last night at all, you know.

B: I know that but it's just that they won and I wish they hadn't.

Here the fact they won is what is bothering speaker B.

Imagine another conversation:

A: You've been complaining for ages about your sales' team. I don't get it.

B: It's just that they don't do what they are supposed to do. And I'm tired of it.

Here the fact they are doing what they are supposed to do is bothering speaker B.

Just that in speech such as that is used to make a specific point that is important to a speaker. In that sense, it is a deictic discourse marker in reference to other things that have been said.

2 - She just thinks they won.

• Someone else thinks otherwise. Here, it is similar to the case above. And can be used like that. It can mean that her main preoccupation is that they won and someone else thinks they did not, for example.

But it can also mean (depending on context): She only thinks that, and has no other particular thoughts about the situation. Then, it's a straight adverb.

3 - She thinks just that they won=is not grammatical (as either regular grammar or the grammar of spoken English). Though a speaker might pause and say something like: She thinks......just that they won, as a way of trying to say after it is too late to say it the other way: She just thinks that they won.

discourse marker

Article: ‘I’m Just Saying . . .’: Discourse Markers of Standpoint Continuity* ROBERT T. CRAIG and ALENA L. SANUSI, University of Colorado.

Our central claim is that these 'saying' expressions are pragmatic devices by which speakers claim 'all along' to have held a consistent argumentative standpoint, one that continues through the discussion unless changed for good reasons. Through close analysis of a series of discourse examples, we show how these discourse markers are used to display continuity, deflect counterarguments, and acknowledge the force of counterarguments while preserving continuity.

[Unfortunately, the article is behind a paywall].

It's not a that clause per se.

Just that is a set phrase: "It's merely (the fact) that".

The just in c is not related to the that there.

HTH.

See also, the related Q.

Here’s what I think about this.

There are several distracting things about this question that have led us all astray.

First, there’s some ambiguity about the first statement which is, I think, irrelevant to the real question. Do the words “It’s just that they won” mean that it is fair that they won, or do they mean that the fact that they won is the only remarkable fact?

Second, the author suggests that the second sample, “She thinks just that they won,” should be corrected to the third sample, “She just thinks that they won.” This suggestion points to a real misunderstanding in a way that has so far escaped discussion.

Let us suppose that in all three samples, all uses of "just" mean "only." The first sample might mean that “it is only their victory [that surprises me, or that bothers me, or whatever].”

What do the second and third samples mean? The placement of “just” (before or after the word “thinks”) makes a slight change in meaning. The second sample, “She thinks just that they won,” would mean that the only opinion that she holds is that they won. The third sample, “She just thinks that they won,” might mean that she is mistaken. She told me that the Eagles won last week, but she just thinks that they won; actually, the Eagles lost.

Now I certainly agree with the author’s sense that something sounds strange about the second sample, while the third sample sounds natural. But as I’ve explained the meanings of these sentences, one expression should not be corrected to the other, because their meanings differ. If we wanted to say that she thinks only that they won, but the old-fashioned flavor bothers us, we should say instead that the only thing that she thinks is that they won.

In the second sample, why does “thinks just” sound strange? In some other sentences we can get away with "just" after the verb without the same stink of antiquity. She does just what she pleases. It works just as well as the name-brand detergent. They sell just the thing you need. And so on.

Certainly part of the problem with the second sample (as I've explained it) is that it means something so strange: she only holds one opinion. But in any case, if we follow the lead in the question -- "just that" -- the sentences do seem to get stagier. I say not that it was proper; I say just that it was legal. I insist not that I receive praise; I insist just that I escape censure. Somehow, we open that window and in flies the 18th century. Maybe it's that evocation of those complicated literary sentences with parallel constructions that make "just that" feel so old.