In Lethal Weapon, actor Danny Glover has a recurring line that has since become pop culture:

I’m too old for this shit.

The line is funny by itself, and works on so many levels. I was reminded of this when a while ago I discussed the concept of age of majority: the age at which a person ceases to be a minor and legally becomes an adult. Where I live, that age is 18 (as in the majority of countries), in the US and some other countries it’s 21. Historically, in Judaism that age was as low as 13 (for males) and 12 (for females). So the age of becoming an adult seems somewhat arbitrary.

While we discussed this, my friend argued that indeed setting a chronological age for maturity is arbitrary, but there is reason behind it. She contends that the reason behind setting a fixed age is one of applied probability (of course she would say that – she’s a mathematician): at age 18 you can expect the vast majority of people to be smart enough to act responsibly; that they are too old for some shit.  

A few days ago I realized that although my fried was probably right in her assessment, the underlying assumption is completely wrong. When we assume that with age people get too old for some shit, we imply that they become smarter as they age. In other words: we assume that there is a minimum age for being smart. Turned around, this could imply that we believe children to be stupid and, more importantly, that there is a maximum age for stupidity. Once a person crosses that age, so we assume, they become smart.

Both are obviously wrong. Stupid children do exist, but they grow up to be stupid adults. Most children aren’t stupid, they are merely young. When they do something stupid, what they do is stupid only from our adult point of view. Smart children do stupid things for smart reasons. Children are relentlessly trying to optimize their surroundings for themselves: they want to get the most pleasure out of the least effort. Their strategies are often stunningly brilliant. The reason most of these fail is because they lack experience and knowledge how the world really works.

But if they are so smart, how come smart children are so gullible? Whenever I tell my godson a tall story, I see his eyes go wide as his chin drops and he believes every word I say. Now, after looking into that little brat’s alive, but coldly calculating eyes, I know for fact that he’s not stupid.

My godson believes what I tell him for a number reasons:

• He lacks experience. We usually can tell truth from fiction based on what we have encountered ourselves. He hasn’t yet experienced much.
• Worse: his experience is tainted: in the few short years he’s lived so far, he has encountered many unlikely stories. Fairytales are a big part of childhood. And not to put too fine a point on this: the exceedingly unlikely and silly stories that priests and believers have told him have wreaked havoc with his sense for reality.
• Evolution has programmed children to believe adults. That way children can pick up important knowledge without having to experience potentially lethal situations themselves.

So when my godson believes an outlandish story it’s not because he’s stupid. It’s because he trusts me. While it’s sometimes fun to tell tall stories to little ones, you always have to remember this: you are lying to them, and when they believe you, it’s not because you are such a good storyteller. Neither because they are stupid. They are smart: they believe you. You are the idiot. You tell them stupid shit. But, admittedly, it is also fun.

So, coming back to the original question we find that there is no minimum age for being smart. Which is good: most of us are smart from the get-go.

Unfortunately, the opposite is also untrue: too old for this shit is something that should, but doesn’t exist. If people became too old to do stupid things when they reached the age of majority, religion wouldn’t have a chance past the age of Kindergarden.