了 vs 是...的 as "factuality markers"

Question

I'm a proponent of 了 as 'factuality marker' (that is it has nothing to do with 'perfectivity or completness of action'. See post: How exactly do time and "tense" work in Mandarin REALLY? for details about this theory.

Now, being what I'm, I've noticed second 'factuality marker' which acts almost exactly as 了. That marker is 是 in the 是...的 structure. There are couple of moments I would like to stress before the question:

1. Contrary to implicit 了, 是 explicitly (by nature of literal translation) states it's nature as "factuality marker".
2. As with 了, sentences with 是...的 tend to be translated in past tense.

The question: If 是...的 and 了 both render situation to facts, which in turn has correlation with being "in the past", what is the difference between them? Why have 2 'factualiy markers' (past tense markers by correlation).

Let's look at two senteces:

1. 我们是今天早上打网球的

2. 我们今天早上打网球了

What is the difference between them? Is there semantic difference? Can you give exaple when 是...的 can be used, but 了 can't?

Answer 1

(今天早上) (打网球)[了]

"打网球" is the fact; "今天早上" is the relative phrase that indicate what time it happened. Remove the relative phrase "今天早上" and write "我们打网球了", the sentence is still a complete sentence. (we still know you've played tennis, just don't know when)

[是] ([今天早上打网球) [的]

the entire phrase "今天早上打网球" is the fact

If you remove the relative phrase "今天早上" and write "我们是打网球的", the meaning would change completely. "我们是打网球的" means "we are people who play tennis"

The 'verb phrase' in [是]+ (verb phrase )+[的] structure is a single item that cannot be broke apart

~

The (verb phrase)+ [了] structure can be in any tense

[是]+ (verb phrase )+[的] structure can only be in past tense

Example:

他(明天)要去美國(了)

"去美國" is the fact; 明天 is the relative phrase that indicate what time it will happen. Remove the relative phrase "明天" and write "他要去美國了", the sentence is still a complete sentence. (we still know you will go to American, just don't know when)

他(是)明天要去美國(的)

It is grammatically incorrect, because 要去美國 is not a face yet, not until tomorrow.

他(原定)(是) 明天要去美國(的)

It is grammatically correct, because 原定(originally planed) is a fact, and it happened in the past.

Answer 2

I'd say the two constructions are used in different contexts. See below example:

A: 你们什么时候打网球的？

B: 我们是今天早上打网球的

A: 你们今天早上做什么了？

B: 我们今天早上打网球了

I'm not quite behind the idea that 了 is 'factuality marker', while 是…的 is. 了 is an indicator of completion.

Answer 3

I feel that 是……的 is not an independent structure. I prefer to parse it as 是 （……的）. 的 is actually a marker of the descriptive chunk before it, transforming it to （I am not sure of that jargon, but something adding 的 to form a noun phrase or else thing is very common）. 是 express quality, feature, etc of the subject in a general sense. When I say general sense, I mean any description of the subject can be pushed after 是, and ……的 is not essential.

1.

大妈：隔壁老王他孩子做什么的呀？

大婶：他可能了！是坐办公室的。

2.

邻居：你家窗玻璃给谁弄坏了？

我：嗨！还不就是早上外面打球的！ （弄坏玻璃的人是早上外面打球的）（Answer only the questioned part）

3.

张老头是昨天早上去世的。

4.

这些都是你臆想的！我可从没说过这种话。（Notice that here 是……的 is far from "factuality marker". 臆想 is my subjective judge.)

……

So it is clear that 是……的 is made of “判断动词” 是 and “名词化结构”……的, and it has nothing to do with "factuality marker ".

P.S. As to 了, things are quite complicated. 了 is neither "completion marker" nor "factuality marker". I ve read a quite informative article and I totally agree with the author's view.现代汉语“了”的语法意义的认知类型学解释