The study of past times and uncivilized races makes it clear beyond question that the customary beliefs of tribes or nations are almost invariably false.  It is difficult to divest ourselves completely of the customary beliefs of our own age and nation, but it is not very difficult to achieve a certain degree of doubt in regard to them.  The Inquisitor who burnt men at the stake was acting with true humanity if all his beliefs were correct; but if they were in error at any point, he was inflicting a wholly unnecessary cruelty.  A good working maxim in such matters is this:  Do not trust customary beliefs so far as to perform actions which must be disastrous unless the beliefs in question are wholly true.  The world would be utterly bad, in the opinion of the average Englishman, unless he could say “Britannia rules the waves”; in the opinion of the average German, unless he could say “Deutschland Ÿber alles.”  For the sake of these beliefs, they are willing to destroy European civilization.  If the beliefs should happen to be false, their action is regrettable.

One fact which emerges from these considerations is that no obstacle should be placed in the way of thought and its expression, nor yet in the way of statements of fact.  This was formerly common ground among liberal thinkers, though it was never quite realized in the practice of civilized countries.  But it has recently become, throughout Europe, a dangerous paradox, on account of which men suffer imprisonment or starvation.  For this reason it has again become worth stating.  The grounds for it are so evident that I should be ashamed to repeat them if they were not universally ignored.  But in the actual world it is very necessary to repeat them.

To attain complete truth is not given to mortals, but to advance toward it by successive steps is not impossible.  On any matter of general interest, there is usually, in any given community at any given time, a received opinion, which is accepted as a matter of course by all who give no special thought to the matter.  Any questioning of the received opinion rouses hostility, for a number of reasons.

The most important of these is the instinct of conventionality, which exists in all gregarious animals and often leads them to put to death any markedly peculiar member of the herd.

The next most important is the feeling of insecurity aroused by doubt as to the beliefs by which we are in the habit of regulating our lives.  Whoever has tried to explain the philosophy of Berkeley to a plain man will have seen in its unadulterated form the anger aroused by this feeling.  What the plain man derives from Berkeley’s philosophy at a first hearing is an uncomfortable suspicion that nothing is solid, so that it is rash to sit on a chair or to expect the floor to sustain us.  Because this suspicion is uncomfortable, it is irritating, except to those who regard the whole argument as merely nonsense.  And in a more or less analogous way any questioning of what has been taken for granted destroys the feeling of standing on solid ground, and produces a condition of bewildered fear.