Not that I knew

[Maybo]

"What's it like in the house?" Harriman asked, pointing to it.
I shrugged. "Like any other house, I guess. Normal." Not that I knew, having only seen the Hall of Old Reading Matter, the kitchen, the living room, and the front hall.

Source: Fairy Tale by Stephen King

Does "Not that I knew" mean "I'm not sure if I know"?

 

[Tarheel]

He's saying he doesn't have personal knowledge of the place -- at least not much.

not that I know - I don't really know
not that I knew - I didn't really know

 

[tedmc]

It is a common phrase used when someone admits that they don't know much about something.

 

[Flask]

"What's it like in the house?" Harriman asked, pointing to it.
I shrugged. "Like any other house, I guess. Normal." Not that I knew, having only seen the Hall of Old Reading Matter, the kitchen, the living room, and the front hall.

Source: Fairy Tale by Stephen King

Does "Not that I knew" mean "I'm not sure if I know"?

"Not that"-clauses can be used with many different verbs and verb phrases. They are used when the speaker/writer wishes to deny the truth of an assumption that the reader/listener might be inclined to make as to why the speaker/writer has just asserted (or is right about to assert) something. I would paraphrase "not that" as "I don't mean to suggest that."

Not that I knew [= I don't mean to suggest that I knew the house was like any other house] . . . .

Here's another example:

We did a number of things on our way to the airport -- not that we had a lot of time.
= We did a number of things on our way to the airport, but I don't mean to suggest, by saying that, that we had a lot of time.

When "Not that"-clauses precede the clause that they comment on, we use "but" between the two clauses:

Not that we had a lot of time, but we did a number of things on the way to the airport.

 

[Maybo]

In the same book:

"He told me to keep track and he'd take care of the expenses." This was half an answer at best. I knew it and Dad probably did, too. On second thought, strike the probably.
"Not that we're exactly in hole on his account. A couple of hundred dollars is all. But the hospital...

Does "Not that..." mean "I don't mean to suggest that we're exactly in hole on his account"?

 

[Maybo]

not that

並非，並不是說, （用於表示認為某事不重要）並非. Learn more in the Cambridge English-Chinese traditional Dictionary.

dictionary.cambridge.org

In the dictionary, I found two definitions and I don't know their difference because they're very similar. How do I know when to use which?

 

[Tarheel]

Not that we're in the hole on his account -- We're not in the hole on his account..

Pay particular attention to the word "not" there.

 

[Tarheel]

not that

並非，並不是說, （用於表示認為某事不重要）並非. Learn more in the Cambridge English-Chinese traditional Dictionary.

dictionary.cambridge.org

In the dictionary, I found two definitions and I don't know their difference because they're very similar. How do I know when to use which?

I'm afraid those aren't good examples.

As for the first one, you wouldn't ask somebody a question if you didn't want to know the answer. As for the second one, apparently the person does mind or why would she ask the question?

 

[emsr2d2]

I find both examples very natural. They'd be used in BrE.
The first works because people frequently ask questions out of politeness, not because they're actually interested in the answer.
The second works as a way of making it clear right from the start that you're not complaining or having a dig at the other person. ("I want to make it clear that I'm not bothered by the fact that you didn't call me but, out of curiosity, why didn't you call me?")

 

[Flask]

In the dictionary, I found two definitions and I don't know their difference because they're very similar.

I look at the second definition given by that dictionary as derivative upon the first rather than as giving a fundamentally different meaning. If a speaker has gone to the trouble of expressly indicating, by means of a "not that"-clause, that s/he doesn't mean to suggest that something is important, then the reader/listener may assume that the speaker does not consider it important.

I'm glad you gave the link to that dictionary definition, though, Maybo. Not only was it satisfying for me to see my paraphrase used in the first (and, in my opinion, primary) definition, but I appreciated seeing an example with a question. That is the one amendment that I must make to Post #4, where I spoke of "not that"-clauses in relation to assertions only, when they can also be used in relation to interrogative clauses.

I'm reminded of an amusing scene from The Never-Ending Story (1986) in which the character of Morla opens his answers to three questions asked of him by the hero of the story with a "Not that"-clause: "Not that it matters, but . . . .' In other words, "I don't mean to suggest that the answer to your question is important, but I'll give you the answer anyway." If you'd like to watch the scene, click here. Another amusing grammatical feature of the scene is Morla's use of the "Royal We."

 

[jutfrank]

Like any other house, I guess. Normal.

The speaker is saying that the house was normal, like any other house.

Not that I knew, having only seen the Hall of Old Reading Matter, the kitchen, the living room, and the front hall.

The speaker is now saying that he did not actually know whether the house was normal like any other house.

The missing words:

It was not the case that I knew that the house was normal, since I had only seen [a small portion of the house]

Is that helpful?

 

[Matthew Wai]

In the dictionary, I found two definitions and I don't know their difference because they're very similar.

I would say "the difference between them" instead of "their difference", which seems to be Chinglish.

Chinglish noun - Definition, pictures, pronunciation and usage notes | Oxford Advanced Learner's Dictionary at OxfordLearnersDictionaries.com

Definition of Chinglish noun in Oxford Advanced Learner's Dictionary. Meaning, pronunciation, picture, example sentences, grammar, usage notes, synonyms and more.

www.oxfordlearnersdictionaries.com