why do so many people lack common sense?
926699
because they also lack common decency, manners, a proper upbringing and education.\n\nSociety is to blame.... society is always to blame.. so they say
802623
because they don't understand
783967
Because they are ignorant!
1157117
Not all people think that, but for a select few it is easier for them to be ignorant than to be educated.
1180218
Because most modern people are idiots. The fact that the Da Vinci Code even exists proves that. Also we have great books like "The Darwin Awards" (great couple of books if you want something to read) that prove beyond a reasonable doubt that most people are idiots.
1059854
Common sense is sense that should be common to most people.  It's not something acquired like a formal education.  Common sense isn't really taught, it's just reckoning that most of us develop.
574901
Some people are truly less intelligent than others.  It isn't necessarily their fault, but we weren't all made equal.  Other people just see things from a different perspective than you can see them from.  Still other people appear to be stupid because they have a different value system than you do so that forces them to make a different decision, not necessarily better or worse, depends on their perspective.
1016911
It seems like a lot of smart people don't have any common sence!
486713
Everyone in the world uses their brain for simple operations like breathing, pumping blood etc. But although this is the answer to your question, it is not the answer you are looking for. The question should read "How many people use common sense?" after looking through the answers you have received, my answer to this would have to be common sense isn't all that common anymore.
1121403
Common sense is no longer common.
904189
because most are uneducated.
97487
Because society is full of ignorance unfortunately.
2170
Because most people do not pay attention to what is going on around them.  They are too busy living in their minds and listening to their mental babble to be aware of what is happening in reality.\n\nI feel like the kid from the movie "Sixth Sense" except I see dumb people not dead people.  Ever have a hunch?  You can't explain it, you are just aware of it.  Most people get hunches and ignore them because they are not rational.  Life is not rational either.  Each of us pretends that it is so we think we have some kind of control over what is happening.
171310
100% of the population thinks that they have common sense.\n\n100% of the population thinks that no one else has common sense
1094926
Yes, because people don't realize that even little things they can give out can cause big problems for them.  It amazes me how stupid people are.
1032618
they lack common sense. This is why they bear the seeds of their own destruction, as in Karl Marx's words.
835831
People usually trap themselves and are oblivious to their\nsurroundings. If you can give more details some of us\nmay be able to help you