'Conventional Wisdom' is built the same way as traditions: over time, as a recollection of people experiences. And the same as traditions, they outlive their originator until nobody that quotes it knows the why's anymore. And that is the problem: conventional wisdom used to be true for someone, but some things are lost and it failed to evolve with time.
For example, it used to be Conventional Wisdom that if someone started coughing blood, dead would come pretty soon. Today, Conventional Wisdom says to bring the person to the hospital and will be recovered in no time ( or so we hope).
Another more radical example: 20 years ago, Conventional Wisdom said that cancer was a death sentence. Today, thanksfuly that is not true anymore.
Outside the realm of medicine, after the industrial revolution it was Conventional Wisdom that a worker should be busy 100% of the time. This belief have carried over the modern times. It used to make sense at the time for some factories, because demand was greather that the production capacity. It ceased to make sense as soon as the production capacity grew, surpacing the demand. But the Conventional Wisdom haven't catched up with modern times.
Does this mean that we should disregard 'Conventional Wisdom' as always wrong? I don't think so. We should understand the why's behind it, we may even learn something that may help us later on. And, who knows, it may even be right.
A here you have the tweets that inspired this post:
RT @tobi: Why is almost every conventional wisdom wrong?-- Yves Hanoulle (@YvesHanoulle) Jan 8, 2012
(with thanks to@YvesHanoulle and @tobi for the though provoking tweet)