Why and why not

In short replies to affirmative statements, we use why?

In short replies to negative statements, we use why not?


  • ‘Jane has decided to quit her job.’ ‘Why?’ (NOT Why not?)
  • ‘Jane didn’t like the proposal.’ ‘Why not?’ (More natural than ‘Why?’)

The structure ‘why should’ can be used to express surprise.

  • I wonder why anyone should want to do something like that.

This structure can also be used to suggest anger or refusal.

  • ‘Lend me a pound.’ ‘Why should I?’

Why can be followed by an infinitive without to. This structure is used to suggest that an action is unnecessary.

  • ‘Why wait for him? He will not come.’ (NOT Why waiting for him?) (NOT Why to wait for him?)

‘Why not + infinitive without to’ can be used to make suggestions.

  • ‘Why not arrange a party in his honor?’ (This is a polite way of saying: I think we should arrange a party in his honor.)
  • Why not buy now and pay later?’
  • Why not make it up with him?’
  • Why not consult a specialist?’

Why don’t…’ can be used in the same way.

  • Why don’t we arrange a party in his honor?’ (NOT Why don’t arrange a party in his honor?)
  • Why don’t you make it up with him?’ (NOT Why don’t make it up with him?)