A new word to describe an old and self absorbed mentality combined with mendacity (a falsehood or lie). It is the act of willful ignorance and continuing to do whatever it is you want to do. An alternative spelling could be Mentalassity but the mendacity aspect gets harder to find.

It is the equivalent of trying to get a suntan on a boat that's sinking. A mentalicitious person is one that somehow justifies the use of a frozen ball of ice in a snowball fight. Mentalacity is the stupid jackasses in my town who are unable to connect the dots about fire danger (the recent one above town, the one burning right now near Davenport and the one up north in Butte County) and how unutterably stupid it is to shoot fireworks off.

Notwithstanding the fact that its illegal, its not even July yet and they're basically just drunk morons. All of that almost goes without saying.