What everybody believes is not always what's actually true. Commonly held opinions are frequently just plain false. Often we are persuaded by authority and repetition rather than by evidence and reality. This tendency to accept what surrounds us makes it difficult to separate what we really know from what we just believe we know... How can people, for thousands of years, believe false assertions that are easily disproved? Answer: Individuals tend to accept ideas if people they know and respect state or believe those ideas. You need to be very clear about the foundations of your opinions. If you believe something only because another person - even a professor - told you it was so, then you should not view your understanding as rock solid... Search for evidence and don't be satisfied until you know the why. The authors of the above quote use Galileo as an example. For nearly 2000 years, everyone believed Aristotle's idea that objects fall at a rate proportional to their ...