筈がない vs 筈はない
事がない vs 事はない
わけがない vs わけはない
I cannot seem to wrap my head around the difference in using が vs は.
I had similar issues with にしても and にしては until it finally clicked after reading some Japanese site about it, but here, I have no idea. Is it just Bunpro being picky, or is using one over the other actually wrong?
In large part, I don’t think there is anything special about these phrases that would make は・が work differently than they do in other cases. At a very high level (because comprehensively treating the difference between は・が is too much for this context and there are myriad better resources out there than me), the key distinction is whether you are identifying a singular thing or a general one. For instance, when you say ことがない you are saying, “not the matter of …” and then giving a specific instance to which you are calling the listener’s attention–to the exclusion of other matters. When you say, ことはない, you’re saying, “as for such a matter as (or ‘the matter of’) …” You aren’t necessarily identifying something singular, but rather speaking at a more categorical or general level. You’re talking about one thing, but not to the exclusion of others. With は, your comment could be construed as a statement about many different things in general (or about one thing from a general category, but not necessarily any of the others in the same category), whereas with が, you’re making a statement only about the specific thing you identified, and usually that’s in a context where you are purposefully bringing it to the attention of the listener/reader.
That might be a sloppy way of putting it, but I hope it helps to some extent. Someone more articulate and better versed in explaining the differences between the two may come along and provide a better explanation (and they should certainly feel free to do so!).
Also note that I’m only talking about は・が in the specific context you are asking about. Please don’t take this as an explanation of those in general (which, again, is too big for a forum post).
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Thank’s for your time. It was helpful, though after glancing at the troublesome grammar points now, I don’t think I can apply this knowledge here.
はずがない | Japanese Grammar SRS (bunpro.jp)
わけがない | Japanese Grammar SRS (bunpro.jp)
ことはない | Japanese Grammar SRS (bunpro.jp)
I have no idea why hazu and wake use ga, and koto uses wa here. Brute memorizing the pattern seems like the best way out of this quandary.
I struggle in these kinds of cases because these phrases can be very contextual. For instance, ことはない can mean either “there is no need to” or “… never is/never occurs.” ことがない can also mean “never is/never occurs,” but it’s only used in contexts where using が is appropriate (e.g. when responding to someone or introducing new information). I agree that rote memorization isn’t the way to go, that’s why I would double back on studying the particles.
And incidentally, there are still others that also fit into those phrases (e.g. では・も・の). That’s why I go back to you have to understand fundamentally how the particles work to determine how and why they’re used differently. Sorry I can’t be more help. For some reason, I end up understanding this stuff intuitively, but I’m awful at explaining it. Maybe that’s because I don’t know it as well as I’d like to think (it’d be hard to argue against that! 
).
You know, after reading your last reply over again, I think I had the wrong idea about what was tripping you up. You wanted to know why the specific particles are being used in the set phrases はずがない・わけがない・ことはない, right? Maybe I can take a stab at that.
はず is a noun (or auxiliary, depending on how you parse it) that basically means what is expected in a given context. It’s usually translated “should, supposed to,” etc. As far as I know, it’s always modified by a preceding word or phrase, which expresses the expectation. When you use がない with はず you are saying there isn’t an expectation that … (whatever the thing is that modifies はず). In practice, this is generally interpreted to mean the thing is unlikely (because it’s not expected). This is usually used with が because that’s the particle used to identify things (e.g. what’s not expected), introduce new information (e.g. responding to a question), etc. These are all the same use cases for が in general. There’s nothing special about はずがない in that regard.
As for ことはない, the reason we use は there is because we are making a general statement, not a definitive one. When you say ことはない to mean “there is no need,” it literally means, “as for the matter of … (whatever is unnecessary), there isn’t any (or ‘there is none’).” This is interpreted to mean the phrase modifying こと isn’t necessary. This is a general statement because we’re not specifically denying the necessity of something else. And this is where knowing は・が apart really comes into play.
When you say ことがない, the implication is that you’re outright denying the existence of something. You’re saying “… never occurs” or “there is no such thing as …” And if you were to say this in the place of ことはない, it could either be a non-sequitur, or it even sound blusterous, giving the listener the impression you’re definitively asserting the non-existence of something. This kind of bluntness can come off as slightly impolite because it sounds a tad arrogant–but certainly not always. The pattern 過去形＋ことがない is a set phrase for saying that you have never done something, and it doesn’t have this tone when used in an appropriate context.
These kinds of things are why I struggled how to reply at first because context ends up imparting a lot of meaning to these phrases. And since you bring up わけがない, well, you’ll find there are five different entries for ～わけ…ない on the site for good reason. There’s a wide range to how わけ is used.
Hopefully, I didn’t just make things worse.
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Actually it makes more sense now. Thank you for taking the time to explain this! I’m gonna read it again and work this out later. I’m gonna also find the Japanese site and search specifcallly for ga vs wa usage, cause that’s what I didn’t try yet.
This is probably one of the easiest ways to think about the difference between が and は in almost all situations, at least in relation to English. It also depends a lot on who is listening, and whether が is needed to highlight something to someone that doesn’t know it, or if は can be used instead.
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If you have already fully availed yourself of Bunpro’s は and が pages, check out some of the helpful links the Bunpro team have provided on the Resources tabs. I recommend Tae Kim and imabi in particular (although the latter can get a little overwhelming due to how comprehensive the author is). Also, if you don’t already have a copy, A Dictionary of Basic Japanese Grammar would be an indispensible book to have at the ready.
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What’s the difference between,
The cat.
A cat.
Same problem, each word is doing triple duty and the nuances are lost in short examples.
Thanks for the input.
I understand you’re trying to make some analogy here, but I wish it was quite so simple.
Unless it is?
Edit.
I mean, in essence, they seem to be similar, but my GA/WA usage is often corrected on HelloTalk.
Even though I’ve read about them, putting this theory into practice is another thing. Unless the people correcting me are nitpicky.
I’m not saying that they are mechanically similar, I’m just saying that they have a similar level of seemingly simplicity but in reality have some many folds and complexities that are so hard to enumerate.