Using negative verb forms with はず


In the chapter [Things that should be a certain
way](http://www.guidetojapanese.org/learn/grammar/should) of Tae Kim's guide,
the author states that in order to express the expectation of something not
happening, one should use something like 「～はずがない」. I was wondering if the
Japanese language distinguishes phrases like "I don't expect him to come" vs.
"I expect him not to come"? In other words, are both of these acceptable:

  * 彼は来るはずがない
  * 彼は来ないはずだ

If not, are there other constructs to express this?




Both are acceptable.

But note that each of them has a different meaning. And these meanings are
subtly different.

> 彼は来ないはずです。

= We have the expectation that he won't come.

> 彼は来るはずがない。

= We do not have an expectation that he is coming.

The difference here is that we are stating our expectation in the first case.
In the second, we are negating an expectation. In the first the expectation is
negative. In the second, the expectation is positive. Turned into a chart:

[code]

                        ～ないはず       ～はずがない      ～ないはずではない
    
    Expectation         -                +                  -
    Statement           +                -                  -
    Net Statement       -                -                  +
    
[/code]

来るはずがない is understood to be stronger than 来ないはずです in terms of the strength of
our belief he wont' come by native speakers.

* * *

> 彼は来るわけがない。

= We have no reason to expect he will come.

But

> どうりで彼は来ないわけです

= It's no wonder he doesn't come




Both are acceptable.

But note that each of them has a different meaning. And these meanings are
subtly different.

> 彼は来ないはずです。

= We have the expectation that he won't come.

> 彼は来るはずがない。

= We do not have an expectation that he is coming.

The difference here is that we are stating our expectation in the first case.
In the second, we are negating an expectation. In the first the expectation is
negative. In the second, the expectation is positive. Turned into a chart:

[code]

                        ～ないはず       ～はずがない      ～ないはずではない
    
    Expectation         -                +                  -
    Statement           +                -                  -
    Net Statement       -                -                  +
    
[/code]

来るはずがない is understood to be stronger than 来ないはずです in terms of the strength of
our belief he wont' come by native speakers.

* * *

> 彼は来るわけがない。

= We have no reason to expect he will come.

But

> どうりで彼は来ないわけです

= It's no wonder he doesn't come

