The most profound advances in human understanding have occurred when "common sense" was overturned by "uncommon sense". The Copernican revolution (the change from an Earth-centred to a Sun-centred view of the universe) is the most famous example (now simply taken for granted and generally unappreciated); other examples are the fact that a feather falls just as fast as a heavy hammer when there is no air resistance to prevent it, Einstein's theory of relativity, and quantum theory.
"Common sense" is to a large extent the recognition of what is considered "normal " and socially acceptable. Evolution has programmed and society conditioned us to see things thus. Politicians love to appeal to people's common sense, because they want to retain the status quo which places them in a position of advantage and privilege. If the physical sciences were as bound by common sense as the social and political sciences still are, as little scientific and technologically progress would have been made as in the so-called social and political sciences.
Nowadays, for example, it is "common sense" for everyone who can afford it to own a car (or two, or more) and to fly away on holiday once or twice a year (or own a private plane). But as ever more of Earth's almost 7 billion inhabitants (and still increasing) can also afford these things, it places an increasingly unsustainable drain and strain on our planet's limited resources and carrying capacity. "Common sense" tells us not to worry about it, because it's "normal " and everyone does it; and besides, experience teaches us that things have always worked out in the past, and - thanks to man's ingenuity - will surely continue to do so in future.
"Uncommon sense ", on the other hand, is telling us that we are now in an entirely new situation, that our growth-dependent economy and grossly materialistic lifestyles are fundamentally unsustainable, the consequences of which pose a dire threat, if not to ourselves (depending how old you are), certainly to our children and coming generations.
It is natural for us to see what is "normal " also as being correct, or at least, not too bad. We cannot help it, because we are hard-wired and conditioned by society to do so. It is the biological basis of morals and ethics, words which in their original tongues (Latin and Greek) simply referred to customary (i.e. normal and acceptable) behaviour.
To a far greater extent than we are prepared to admit (except in the nicely compartmentalised field of biology), man is an animal, a "prime ape" (if you will excuse the pun) - in fact, Earth's "Greatest Ape "- and although we have a good deal of social behaviour programmed into us, it evolved to serve the survival and advantage of individuals and their family groups, TRIBES, and under some circumstances, NATION – but NOT a wider humanity, and certainly not our species as a whole. This is why efforts to address even regional problems, let alone state (national), inter-state and global problems, which now threaten our very survival, have been and - without a radical change of awareness and behaviour - will continue to be so hopelessly inadequate.
In the past, rules of behaviour (morals) were passed down from generation to generation and generally contributed to the group's survival. An individual might question the validity of a rule prohibiting the eating of a particular mushroom, for example, but he was well advised to heed it. Natural selection soon eliminated those who didn't. Conforming to the norm and following authority and majority makes logical and practical sense (otherwise evolution would not have hard-wired us to do so). When scientists (renowned for their rationality) conduct an experiment which produces lots of data they will often disregard any that do not fit the general pattern, assuming them to be the result of experimental error. It is usually the sensible and correct thing to do.
Or imagine being in a building when a fire alarm sounds. You have no idea where to head and there are no signs to indicate it, but suddenly you see a large number of people all rushing in the same direction. What do you do? Most likely you assume that, unlike you, they know which direction to head in, and join them. It seems rational to suppose that they will not all to be mistaken. However, that assumes that they all came to their decision independently. In practice it may be that just one person thought - perhaps mistakenly - that he knew the right direction and started heading in it, and others simply followed, creating a chain reaction. They might all be rushing towards danger instead of away from it. By analogy, this also applies to the direction in which modern civilisation is heading, i.e. towards catastrophe; but because virtually everyone is moving in the same direction it is very difficult - psychologically and practically - to believe that this could be true.
Another example: when I see lots of people walking and skating on a frozen lake (as I often did when I lived in Germany), I'm inclined to assume that it is safe to join them. Good sense, however, will tell me to consider other factors as well - like how cold it has been and for how long, or actually to measure the thickness of the ice.
Thus, we are biologically programmed and socially conditioned to conform to the norm. Not that everyone always does, of course, but in general we do. In the modern world things are confused by contact with and knowledge of foreign cultures, and the fact that someone who appears to be courageously non-conformist, may in fact simply be conforming to other, unfamiliar norms, such as those of a street gang, for example, or of a religious sect.
In unfamiliar social situations, where we are unsure how to behave, we all usually look to see how others are behaving, in order to fit in with them.
Conforming to social norms is an essential characteristic of human behaviour, inherited from our animal forebears, which has served our survival and advancement. However, recent developments - the exponential increase in human numbers and their impact, hugely increased through the application of modern technology, on our planet - have led to a fundamental change (in fact, a reversal) in such behaviour's survival value.
In the modern world it is perfectly normal for lots of people to make extensive use of a car and fly off on holiday once or twice a year. Our biological programming and social conditioning thus respond by telling us that it must be okay for us to do so as well. On the other hand, our recently acquired, more enlightened, human nature (e.g. our intellect, in its literal sense) tells us that what may be of little consequence for our planet when just a few (million) people do it, is likely to have catastrophic consequences if 100's or 1000's of millions of people do the same thing.
In the past, playing safe for the best chances of survival, meant following the norm and doing what most other people did. But that has now changed. In the modern world, such behaviour has become a threat to our survival.
We all like to think that we see the world with our own, unimpaired eyes, but in fact each of us sees it through a unique pair of very strong glasses, the highly complex, distorting lenses of which we have acquired from our parents, peers, books, the media, and society at large. Although I believe that I see some very important things more clearly than most (otherwise I wouldn't be writing this), my glasses are not uniformly less distorting that those of others. The lenses are very complex. Some things, I'm sure, I see more distorted than others.
Many years ago I saw a demonstration on TV, in which a man's perception of his environment was remarkably altered through posthypnotic suggestion, following which, when light balls were thrown at him, he ignored them completely, as if they did not exist. When questioned about his behaviour, which had been influenced by the balls, he rationalised it - just as we all rationalise our irrational behaviour to prevent ourselves from becoming fully conscious of what we are doing to our planet.
Among my parents' and grandparents' generations it was common to hear it said that they wanted their children to have it better than they did. Most of us certainly got what they wanted for us, and I for one am very thankful. The question now is, what do WE want for OUR children and grandchildren? For my part, I would like them to have it as good as I have. But they won't, not the way things are going, unless we break out of the trance we are under and come out of denial about what we are doing to our planet.