After observing, sorting and classifying, noting common properties and formulating general rules or tendencies, the next natural step in the advancement of knowledge is trying to account for things. When we have discovered that things generally happen in a certain way, we very naturally want to know why. Experience tells us that every event has a cause, and will be followed by an effect; natural curiosity impels us to try to trace effects to causes; natural desire to plan our future — to avoid failures and to repeat successes — impels us to try to forecast the effect of causes.
Because an effect is the consequent of a cause, and a cause the antecedent to an effect, we are apt to assume that two events or conditions, one of which precedes or follows the other in point of time, are causally connected. This is an error to which ignorant and superstitious people are especially prone. A man walks under a ladder and soon afterwards is run over and killed; superstitious people will tell you he was killed because he walked under the ladder. The temptation to fall into this error is especially strong when one or other or both of the occurrences are more than ordinarily striking; or when there is apparently a constant recurrence of similar happenings in conjunction. Then even the sceptic may begin to think that "the long arm of coincidence" has been stretched too far and he may be tempted to suspect that "there may be something in it after all."
And so there may be; but we are not justified in asserting that there is, until further trial has been made. We must first ask ourselves, "Does the so-called cause adequately explain the effect? Are there any other forces that may have interfered?" We cannot point to one definite cause until all other adequate causes have been eliminated. The imposition of tariffs in this country was followed by the fall of prices to an almost unprecedented low level. We cannot conclude that the imposition of tariffs caused prices to fall, until we have found out whether other factors were at work. It might be advisable, too, to find out whether the same result was evident in other countries when tariffs had been in existence for some time, and to inquire whether there was a general fall in world prices at the same time.
A habit, similar to that described in the previous chapter as rash generalisation, tempts us, in our efforts to simplify things, to attribute an event to a single cause, when a multitude of different causes may have combined to bring it about. When we know how various and involved our own motives may be in taking any particular line of action, we ought not to be too ready to attribute, say, the war of 1914-18 solely to the desire of Germany for aggrandisement. Incidentally, we ought to beware of explaining the behaviour of our fellow-creatures by imputing motives — good or bad — as the springs of their action.
Again, in searching for causes we should be careful not to confuse the cause with the occasion. The murder of the Austrian Archduke at Sarajevo was the occasion, not the cause, of the outbreak of war in 1914. The responsibility for an explosion lies with those who laid the charge and the train, not alone with the man who applied the match.
Another common error is to assume that two conditions, found side by side or in conjunction, are causally related. Because we often find poverty and drunkenness in the same home we must not assume that one is the cause or effect of the other; they may both be the effects of another cause, e.g. bad housing conditions.
And, by the way, so-called "coincidences" will nearly always be found to depend upon carefully selected instances. As for "Chance," Aristotle invented it
"to cover up the astonishing fact that there were certain phenomena for which he found himself wholly unable to account!"