Why saying:

"It is equivalent to saying that"

is true rather than:

"It is equivalent to say that"

I always get confused about using the word after "to" because when I was learning English I was told that after to we have to use simple verb. Could you elaborate this for me?

  • As expressed in a comment to one of the answers, it's not necessarily incorrect to say the latter. In some contexts, it would be fine. It's only in general that the first would be used. Commented Jan 10, 2019 at 4:25

2 Answers 2


"to" can introduce an infinitive, sometimes with the meaning of purpose, and it can also be a preposition. When it is a preposition, it is followed by V-ing.

In It is equivalent to saying that... "to" is a preposition, and the sentence means that something is the same as saying something else, for example:

  • Walking out on your wife is equivalent to saying you don't love her anymore. (Walking out on your wife = saying you don't love her anymore)

When you establish the equivalence between two things, if one of those things is a verb it has to be a GERUND.

For the infinitive to work, we can think of other adjectives, for example:

It is reasonable to say that this is a good method to learn English.

In this case, "to say that..." is the infinitival subject of the sentence.

  • 1
    There probably are contexts in which "It is equivalent to say that..." works (something like, "It is a terrible thing to say that you hate puppies. It is equivalent [as in, equally bad] to say you hate sunshine."), so you might want to moderate that claim.
    – Juhasz
    Commented Jan 9, 2019 at 23:15
  • @Juhasz: What do you mean? you are saying "It is a terrible thing to saying that you hate puppies" is stronger that "It is a terrible thing to say that you hate puppies.?"
    – Saeed
    Commented Jan 10, 2019 at 15:17
  • 1
    @Saeed No, what Juhasz validly said is that it may be correct to say "It is equivalent to say..." when the adjective "equivalent" is not used to establish an equivalence but to mean "as ... as", for example: To say you hate puppies is terrible. To say you hate sunshine is equivalent (i.e. as terrible as saying you hate puppies). Therefore, it would be possible to say: "It's equivalent to say you hate sunshine". We cannot say "Saying you hate your puppy is equivalent to saying you hate sunshine" because those two sentences mean different things and are therefore not semantically equivalent.
    – Gustavson
    Commented Jan 10, 2019 at 15:24

Because that is the kind of complement that equivalent to takes. (As Gustavson says, this is not an infinitive: equivalent does not take a direct object, but requires an indirect object with to).

Like takes the same kind of complement (eg "That is like riding a bike"). On the other hand, necessary takes an infinitive with to (eg "It is necessary to put a stamp on before posting").

There is no rule to this: you simply need to learn what each particular word requires. Sorry.

  • In my experience as a teacher, there are very few cases of the preposition "to" followed by gerund. Perhaps OP should learn those (be devoted to, look forward to, come down to, get down to, be limited/confined/restricted to, etc.).
    – Gustavson
    Commented Jan 10, 2019 at 1:06
  • @Gustavson: but equivalent does not come from the same family you mentioned, could you give me more example?
    – Saeed
    Commented Jan 10, 2019 at 15:20
  • @Saeed There are certain adjectives followed by to and certain phrasal prepositional verbs with to that will be followed by the V-ing. The rule of thumb is, if you can use a noun, then you should use a gerund: This is close to failure / This is close to being/becoming a failure.
    – Gustavson
    Commented Jan 10, 2019 at 15:34
  • @Gustavson: are they exactly the same? with V-ing and without?
    – Saeed
    Commented Jan 10, 2019 at 17:40
  • @Saeed Yes, but I don't know if you get my point. My point is that the V-ing is the nominal form of the verb and therefore equivalent to a noun. Another example: Most of his time is devoted to solving mathematical problems / Most of his time is devoted to the solution of mathematical problems. Can you see that "solving" is equivalent to "the solution of"?
    – Gustavson
    Commented Jan 10, 2019 at 19:14

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