たform+こと が/は(particle) ない?

Question

Is it

みたことがない

or

みたことはない ?

I'm not sure about the particle for this. Can both be used? Or which is better? (And why is it so?)

Thanks!

Answer 1

This is a good question because quite a few Japanese-learners do use the two as if they were completely interchangeable. They are not.

「みたことがない」

makes a simple and neutral statement saying you have not seen something. You just do not have the experience. If I said:

「パイプオルガンを見{み}たことがない。」

all it means is that I have not seen a pipe organ. Plain and simple. I am not implying anything.

「みたことはない」

, however, implies either:

1) you have not seen A, but you have B (or C)

or

2) you have not seen something, but have done something else (other than seeing) with/about it.

This is all made possible by the use of the contrastive は.

Thus, if I said:

「パイプオルガンを見たことはない。」

I would be implying either:

1) I have never seen a pipe organ, but have seen another instrument.

or, for instance,

2) I have not seen a pipe organ but I have listened to pipe organ music.

The smallest words are often the most important words in Japanese. I am, of course, referring to our particles.

Answer 2

～をみたことはない CAN carry contrastive nuance, but it is the same as ～をみたことがない in, say, 50% of the cases. This is because は is used commonly in negative sentences without any contrastive connotation. See: Why is the topic marker often used in negative statements (ではない, ～とは思わない)?

originally, the pattern ～ではない was used to only mark a strong contrast of the entire predication to something else (e.g. something that was said or implied before by someone else), but later became more and more popularized until what originally was a contrast marker became an almost necessary feature of the negative form.

---

For example, this this news article uses both expressions:

• (私の就任から)こんなに悪い試合は見たことはない。
• (長年、監督を続けていますけど、)こんなに内容の悪い試合は見たことがない。

...both of which (neutrally) mean "I have never seen such a bad game." I can see no significant difference between the two here. ～は見たことがない MAY imply contrastive nuance depending on the context, but it's often quite neutral and is safely interchangeable with こんなに悪い試合を見たことがない。