Dumbitude is a communicable disease. Wrap your mind in the prophylactic device of clear reason whenever you venture out into the realm of the promiscuous pseudo-intellectual. Luckily, it is a disease that can be treated, but one of its common symptoms — as with alcoholism — is denial. It is only with great luck or cleverness that one may induce the afflicted to submit to treatment.
It is rarely (physically) fatal. Would that it were more lethal to those infected by some of the more particularly chronic strains, for the good of the rest of the species. It is, after all, quite dangerous to the continued life of the free and open mind.
In our intellectual intercourse, it is those with whom we are most intimate that present the gravest threat to the health of our minds. Be vigilant and aware of the dangers of those most promiscuous in their unprotected interactions with others, but more importantly you should take great care in your interactions with those closest to you, for the most inconspicuous hint of infection may take root and thrive when you do not take sufficient steps to protect yourself.
Whenever you detect the nascent symptoms of dumbitude in your intimate companions, it is for their own good that you should illuminate them. Bring them into the stark light of day to be examined. It is in the early stages of dumbitude that one is normally best able to overcome the impulse toward denial, and take steps to begin curing the illness. Be always ready to consider such warnings from others, as well — but never let their warnings take the place of your prophylactic power of reasoning.