I have read in Longman English Grammar, page No 246, that we use 'will' and 'would' to describe natural tendency

Like the simple present tense [> 9.6-8] will (with a 3rd person subject) can refer to general truths or to the qualities of things; would can sometimes refer to the past.

Water will boil at 100°C It won't boil at under 100°C

Q1: How is this sentence different from: Water boils at 100'C?

I planted a vine last year but it wouldn't grow because it didn't get enough sun.

Q 2: How is “But it wouldn't grow” different in meaning from “But it refused to grow” and “But it didn't grow”?

  • 2
    What do you mean by natural tendency?? In the third person, questions in English with the word WHAT, start like this: What does x mean; What did x mean; What would x mean.
    – Lambie
    Commented Nov 19, 2016 at 17:02
  • The two words natural and tendency are well defined in every dictionary. There is nothing abstruse about the phrase "natural tendency". What do you think "natural" means? What do you think "tendency" means? You may be able to answer this question on your own, which is our preferred outcome! Commented Nov 19, 2016 at 20:36
  • I'm inclined to think you haven't read what the book says—the explanation it provides is transpicuous. I would also recommend reading (non-grammar) books in English.
    – user3395
    Commented Nov 25, 2016 at 20:29
  • I've specified my question
    – yubraj
    Commented Nov 26, 2016 at 14:54
  • 1
    @Catija don't be so nerdy, it's English. Your average Joe on the street will say this statement. It's your typical bog-standard example phrase that many grammar books will cite to illustrate when and how to use the simple present tense: "water boils at 100 C". (yubraj sharma see all the times I used "will"?) And it's the one used by Longman, write a letter of complaint to them, or write an answer here saying the statement is false and inaccurate.
    – Mari-Lou A
    Commented Nov 27, 2016 at 14:35

3 Answers 3


Another way of saying natural tendency is calling it proclivity, both will and its past equivalent would are used to express, what Michael Swan (Practical English Usage) describes, habits and characteristics

Will and would can be used to talk about repeated and habitual behaviour. Would refers to the past.

  • When nobody's looking, she'll go into the kitchen and steal biscuits
  • On Sundays, when I was a child, we would get up early and go fishing.

A.J.Thomson A.V.Martinet in their book A Practical English Grammar (4th Ed) explain this nicely, better than I could

Habits in the present are normally expressed by the simple present tense; but will + infinitive can be used instead when we wish to emphasize the characteristics of the performer rather than the action performed. It is chiefly used in general statements:

  • An Englishman will usually show you the way in the street (It is normal for an Englishman to act in this way.)

This is not a very important use of will, but the past form, would, has a much wider use and can replace used to when we are describing a past routine.

  • On Sundays he used to/would get up early and go fishing. He used to/would spend the whole day by the river and in the evening used to/would come home with marvellous stories of the fish he had nearly caught.

Thus saying that water will boil at 100°C is stating a general characteristic; a natural tendency: the general inclination of water when it is heated at that temperature. Using will in this way is uncommon, but it shows why its past equivalent, would, is often used to express repeated actions in the past. However, would and used to are not always interchangeable.



  • Italian middle schools used to teach Latin. = In Italy, Latin was taught at middle school.
  • In Italy middle schools would teach Latin. = same meaning as above

BUT in the negative sense

  • Italian middle schools didn't use to teach English. = In the past, English was never taught at middle school.
  • Italian middle schools wouldn't teach English. = In the past, Italian middle schools refused/did not want to teach English.

In order for wouldn't to convey the same meaning as didn't use to, the adverb never could be employed.

  • Italian middle schools would never teach English.

Other examples

  1. As a child I didn't use to wear glasses because I had good eyesight = I didn't wear glasses as a child because my eyesight was good.

  2. As a child I wouldn't wear glasses, although my eyesight was poor. = I refused to wear glasses when I was a child, even if my eyesight was not good. (different meaning)

  3. As a child I would never wear glasses, although my eyesight was poor = similar meaning to 1.


Water boils at 100°C

You are expressing a characteristic of water.

Water will boil at 100°C

You are saying that if you heat water to 100 degrees Celsius, that it will boil. It's equivalent to the first sentence only because it's commonly known and a proven fact that water boils at 100 degrees Celsius.

If you were only really sure that water would boil at 100 degrees Celsius (perhaps you may have modeled it or predicted based on strong information), but haven't actually tried it yet, you would want to say will boil versus boils. You would never do this for water, of course, but maybe other things like the weather.

How “But it wouldn't grow” is different in meaning from But it refused to grow and But it didn't grow ?

To refuse means to willingly (as in able to make a decision) reject or not do something.

Do vines have independent wills like people? That's a deep philosophical argument, and a gardener or someone who likes plants may prefer to think of them as having an independent will, whereas someone who doesn't care would think if it as an object.

In any event both of them get the idea across that there is no growing happening, so it's just a matter of style.


"Tendency" means "more often than not". It doesn't usually imply a strong probability, just a mild one unless qualified with "strong" ("strong tendency") or equivalent. So it has very little to do with "will" or "would", which are both definite, "will" being absolute and "would" being conditional.

"Natural tendency" simply means the tendency is usual, ordinary, unforced.

The difference between "water will boil" and "water boils" is syntactic, not semantic. Both describe the same process and outcome.

"Wouldn't grow" vs "didn't grow" is largely syntactic. So, strange as it might seem, is "refused to grow". "Didn't" states the bare fact. "Wouldn't" and "refused" imputes agency to the plant: all the conditions were (allegedly) correct for growth, but growth did not occur. So what stopped it? The plant refused/wouldn't/decided not to, that's what stopped it: the plant chose not to grow.

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