Meh, lets not.

In my experience, older people have to make conscious effort to maintain critical thinking and reasoning and not start lazily regurgitating settled, memorized opinions they've come rely on as absolutes, intead of allowing those beliefs to be subject to fresh challenges from novel perspectives that may change those opinions. Many do make that effort, and many do not. To paraphrase my favorite fictional character, if you refuse to change your mind, then you will die stupid.

Individuals are individuals of course though. I'm of the opinion that, on an individual basis, beyond the age of around 12, age is an extremely poor metric to estimate someone's intellect, wisdom, and insight. I'm in my mid 30s and have a master's degree in psychology with a 3.9 GPA. I recognize that there are 18 year olds that dwarf me intellectually, and more commonly 80 year olds who've lived lives devoid of reflection, who will die defending their long dead pappy's narrative about how the world works with anger rather than reason, solely because that's what they were told to believe. I have pity for that type, but very little patience.