Is it correct that a noun can be followed by an infinitive?

Question

I have been learning Spanish for 2 years now, and have consistently seen that the infinitive form of the verb can only exist:

* after a preposition, or
* after another verb.

For me this has been a fundamental rule of grammar which has served me very well. So I am shocked to find this sentence:

me da miedo dejar solo al niño (I'm frightened to leave the child alone) (*)

which breaks the rule because the infinitive follows a noun. I would expect to see a preposition between the noun and the verb, for example:

me da miedo (de) ir al dentista (I dread going to the dentist).

I note that similar structures have to follow the 'normal' rule. For example:

tenían miedo de hablar (they were afraid to speak) (*)

Is there something special about the verb dar in the 'gusta' form that allows the noun + infinitive; or is this a general rule that I have only now come across? So what is the correct grammar rule for the placement of infinitives?

(*) source: Merriam-Webster dictionary : http://www.spanishcentral.com/translate/miedo

Answer 1

The problem you have is that you have a list of uses of the infinitive, as it were just a recipe.

The most important thing to note, about the infinitives, is that they are the "nominal form" of any action.

So, when using the infinitive form of a given verb, you can tell things about that verb (about that action). For example, if the fact of leaving alone that child makes you scared, then the fact of leaving him alone is the subject; the action is make you scared; and the object receiving the action of that verb is just yourself.

The sentence that shocked you is not written in the canonical order. This is how you must read it to understand it better (then, you'll be able to use it in the order you like):

Dejar solo al niño me da miedo. (Leaving the child alone scares me).

In this usage of infinitive, sometimes an article is used with it:

El dejar solo al niño me da miedo.

Or you can write it using another verb:

Dejar solo al niño me asusta.

A simple analysis may be this:

Dejar solo al niño      me asusta.
\________________/      \_______/
     subject            predicate
\___/ \__________/
noun  noun complement
                        \_/
                    direct obj.
                           \____/
                            verb

Answer 2

I can't give you an explanation but this is completely normal, it is not a variation, it's pure spanish:

Me da miedo hablar.

Nos da miedo hablar.

Les da miedo hablar.

If we change a little the sentence, we see the "de":

Tengo miedo de hablar.

Tenemos miedo de hablar.

Tienen miedo de hablar.

And if we change the first ones

Hablar me da miedo.

Hablar nos da miedo.

Hablar les da miedo.

¿Qué te da miedo? - Me da miedo dejar solo al niño.

¿De qué tienes miedo? - Tengo miedo de hablar.

Google trends show us that it's used in the entire spanish speaking world