The first of the big three delusion is that certainty exists in any way and is in any way possible. Since uncertainty is so uncomfortable the concept of certainty is imagined into existence. Throughout the world there are oases of comfort scattered around the globe. There are also equilibriums of prosperity. Certainty does not exist.
Number two is the notion that the human species is in some way anointed. It is a human instinct to exalt the species as well as the concept of self. In disciplines like political science and economics the first order of business is to exalt the species as well as the self and ascribe noble attributes to everyone. There is no way to generate meaningful answers to issues when these notions are packed into a discipline before study begins.
Number three is the belief each individual has of being special. The notion of being special is at the root of all mental illness other than what is biological. It is hard for an individual who has no since of being special special to feel slighted by others.
Human beings suffer from many more delusions. Most other delusions could not exist without individuals first indulging in the three delusions I just mentioned.