As important as the quantity or quality of knowledge present in a system is the attitude toward gathering more. Often, people are hampered by their reluctance to learn more, although usually learning is helpful—particularly if it leads to a stronger, more inclusive belief structure.

Nevertheless, the desire to know is often tempered by a sense that learning more would be emotionally disturbing. This complicates any consideration of stupidity, when "Knowing" is one of the defining criteria for the condition. If a person does not know what is going on, he might do something maladaptive, but it is not stupid as such. However, if a person is making a point not to find out relevant information in his environment, is that not even stupider? If it would seem so, bear in mind we all have defense mechanisms to protect us from awareness of embarrassing cognitions and psycho/cultural mechanisms to help us cope with the unsettling cognizance of our inevitable death. Thus, the condition of "Knowing" appears to be of little value when one attempts to determine if an act was stupid or not.

Once people gather information, they treat it in one of two ways, depending on whether they like it or not. The double standard is quite simple: that which is acceptable is accepted; that which is unpleasant is suspect. It might be ideal if all data were treated equally, but personal biases predispose people to be selectively ignorant.

In most situations, ignorance promotes a common characteristic of stupid decisions—irrelevance. When stupidity is in full glory, the most discrepant cognitions are somehow matched up in the most implausible ways. Further, obvious relevancies are ignored, so the behavioral world takes on the bizarre, chaotic quality of a Wonderland gone berserk. Cause /effect and means/ends relationships are coined at random. The monumental is trivialized and the crucial disdained as an afflicted mind locks in on and pursues its own worst interest with unrestrained abandon.

Unfortunately, the determination of "Relevance" is quite judgmental, so stupidity is an arbitrary/subjective phenomenon. Deeds once considered stupid may turn out to be brilliant. On the other hand, achievements initially hailed as works of genius may later be exposed as moronic (as happened with the Maginot Line and the Edsel).

While much is made of the human brain's ability to associate various cognitions (ideas) in relevant cause/effect relationships, the amount of stupidity in the world suggests that the brain might also prevent or inhibit such functional associations while it promotes irrelevant connections.

stupidity.net