Idiom meaning someone thinks he/she is smarter than anyone else because of age and experience

Question

I am looking for an idiom that describes a person who thinks he or she is smarter than anyone else; just because they are older than someone, they presume that they are also wiser; but that might not be the case (smart aleck, know-it-all, holier-than-though, malapert, don't function in this case). I am looking for something related to intelligence and age, even used humorously.

The question actually came from one of my students, I teach English as a foreign language. I am 28 and my student is 34 years old, and through humour he told me I should pay attention to what he is saying, because he is older than me and therefore wise and smarter, and he asked is there some expression/idiom/phrase that could be used to describe him and I was a bit stunned at the moment because I cannot find something that links age and intelligence in this sense.

Answer 1

One useful expression might be this:

old enough to know better

This is something of a double-edged phrase. On the one hand, it seems (at least on its face) to accept the proposition that being older naturally confers a certain degree of wisdom that a younger person (or the same person at a younger age) might not be expected to have. But on the other hand, at least in my experience, "old enough to know better" usually comes up in contexts involving foolish, ill-advised, capricious, or dunderheaded conduct that is all the more deserving of censure because it was done by someone who can't claim youthful ignorance as a legitimate excuse for the indiscretion or bad behavior. "I can't believe you did that—you're old enough to know better!"

I couldn't find any proverbs that explicitly assert that being older automatically makes a person smarter, although that may be the implication of these two sayings from Rosalind Fergusson, The Facts on File Dictionary of Proverbs (1983):

Experience is the mother of wisdom.

No man is born wise or learned.

But several proverbs (also listed in Fergusson) deny any necessary connection between age and wisdom:

The brains don't lie in the beard.

Old age doesn't protect from folly.

Wisdom goes not always by years.

There's no fool like an old fool.

Answer 2

If I'm allowed to twist a common saying Age Doesn’t (Always) Equal Wisdom, I'd say a phrase for your question would be:

He thinks his age equals wisdom.

But that doesn't exactly describe the person.

_{See examples on Google.}

Answer 3

An "age chauvinist," maybe.

An "ageist" comes close, but means one who discriminates based on age, and so could also plausibly describe a young person who feels superior to old people.

Neither of these explicitly draw a link between age and intelligence, however.

Answer 4

Speaking from authority or Argument from authority

The basic structure of such arguments is as follows: Professor X believes A, Professor X speaks from authority, therefore A is true. Often this argument is implied by emphasizing the many years of experience, or the formal degrees held by the individual making a specific claim.