What if / suppose / supposing
Rain at the Taj Mahal

Pattaraporn from Thailand writes:

I would like to know the meaning of what if and how to use it. Thank you so much for your answer.
Roger Woodham replies:
  We use what if at the beginning of a question when we are asking about the consequences of an action, particularly one that is undesirable. We refer in this way to present or future circumstances:
  • What if I am made redundant and have no work? What shall we do then?

  • What if there are jellyfish? You won't want to swim in the sea then.

We can also use this structure to refer to past circumstances:

  • What if the ice had cracked? You would have disappeared into the icy water and wouldn't be here to tell us about it.

  • What if you had slipped? You would've fallen right down the cliff. There would have been nothing to save you.

As you can see from these examples, what if questions give us an alternative way of expressing conditional ideas. We could have said:

  • What shall we do if I am made redundant and have no work?

  • You won't want to swim in the sea, if there are jellyfish around.

  • If the ice had cracked, you would've disappeared into the icy water and wouldn't be here to tell us about it.

  • If you had slipped, you would have fallen right down the cliff

However, none of these examples sound as dramatic as "what if...?". Note that the final two examples in these sequences refer to imaginary situations that did not occur, for which we need the so-called 'third' conditional.


  
   

Suppose, supposing or what if?

We can also use suppose or supposing as an alternative to what if when we are asking about the consequences of an action:

  • I'm not going to take my umbrella.
    ~ Suppose it rains?
    ~ Supposing it rains?
    ~ What if it rains?
    ~ What will you do if it rains?

  • I just caught the last flight of the day with two minutes to spare!
    ~ Suppose you had missed the flight?
    ~ Supposing you had missed the flight?
    ~ What if you had missed the flight?
    ~ What would you have done, if you had missed the flight?
  
 

What if / suppose / supposing for suggestions

When referring to present or future circumstances, we also use these structures to introduce suggestions in a rather tentative way. We are not so confident that the person we are addressing will say 'yes', so we do not use the more enthusiastic Let's… or Shall we…? in these circumstances:

  • What if /suppose / supposing we invite Geoffrey to fill the empty place at dinner? How would you feel about that?

  • We haven't got any cream for the sauce. Suppose / what if / supposing we use milk instead? Would that be all right?

  • And I don't have a table cloth for such a large dinner table. Suppose / supposing / what if we were to use the green sheet from the double bed? It would look good with the yellow table napkins.
   

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