What we think of as stupidity comes in many forms, and one that we can actually do something with for ourselves is the stupidity that comes from lack of receptivity.
Again, it may be helpful to see this through the three centers.
When there is a lack of receptivity, our view closes down. We cling to one view, are unable to see the validity in its reversals or other views that seem to oppose our initial one. Since they all hold some validity and practical value, we limit ourselves seriously and become stupid and act stupidly in that sense.
And since we see ourselves as right and others as wrong, it tends to close our heart and bring up fear. What if I don’t get what I want? What will they do that don’t agree with me?
Our heart closes down as well, or is at least ambivalent, on guard, looking for signs to close down. We experience separation. We are not motivated to seek to understand the other. It is all to easy to dehumanize the other. (Whether it is ourselves, our spouse, a colleague, a political opponent, or anyone else.) And we live from fear.
And in all of this, we miss out of the wider reality of the situation and become stupid.
We all too easily get caught up in reactive emotions, and blinded by them sometimes. This too closes down the heart and view, making it difficult to see ourselves in and understand the other. Blindly acting from reactive emotions is obviously stupid, as it is easy to see after it happens.
So we make ourselves stupid by closing down through a lack of receptivity, resisting experience, identifying with stories, and much more.
The good news is that we can also make ourselves smart by doing the opposite. By fully allowing experience, inquire into beliefs, finding that stable earthy nurturing fullness that provides a buffer against being swept up in reactive emotions.