5. COMMON ERRORS OF OBSERVATION AND EXPERIMENT.
The rules for scientific observation have suggested certain common errors which may now be considered.
(1) Preconceived ideas.
There is not an unholy belief nor an unwholesome theory which cannot be bolstered up by means of apparent facts. For example, that monstrosity of Puritan thought known as “Salem Witchcraft” was substantiated by facts honestly observed. Again, having made up his mind that it is going to be “so and so,” the statistician goes out into the highways and byways and gathers the facts which vindicate his judgment. Further, the democrat finds that the majority of the voters are democrats; while the republican is confident that two-thirds of the voters are for republicanism. Here again is the fallacy springing from a preadjustment of attention. We see what we want to see. Only the highly trained observer is able, with impunity, to make use of preadjusted attention, and even with him, it is not easy to remove from the situation belief and prejudice.
The true observer undertakes his work with his mind open to anything which the eye may bring him, though it may topple into the dust his dearest theory and most cherished belief; he proceeds—the mind a “clean white page.”
(2) The “observed” and the “inferred” confused.
This error has already received some attention. It may be remarked further, however, that, psychologically considered, observation is a matter of interpreting the newby means of the old. Of necessity the interpretation, whatever it may be, will assume the complexion of the particular “old knowledge” which the mind is able to use. In short, a man will see what his previous environment has trained him to see; the conscientious gardener sees the weeds, whilst the artist may see nothing but the flowers. It follows, therefore, that all observation must be largely a matter of inference based on experience. In looking at the moon, for example, all I actually see is a patch of color; the form and distant location of the moon being a matter of experience.
The inference referred to in this heading is not that which is necessary for perception, but that which is suggested by perception. To illustrate: It is icy; three men are running for a car; Smith raises his arm; Jones slips to the ground; and Brown testifies, that “Smith knocked Jones down.” Brown observed, that Smith assumed the proper attitude and that Jones conveniently went down at the right time; and then inferred the rest.
(3) Ignoring the exceptions.
This comes through an over anxiety to prove our theory. With this mental attitude, the observations which are corroborative will so completely fill the mental field, that the exceptions are made to seem of no consequence. This accounts for the superstition attached to thirteen. As a coincidence some one at some time died who had previously eaten at a table where there were thirteen. Perhaps during the life of the superstitious one this happened on two or three occasions, but the fact so impresses the subject that he ignores the dozen times whendeath did not follow. Other generalizations belonging to this class are (1) people never die at flood tide; (2) there must be three accidents in succession; (3) the first sight of the new moon over the right shoulder is a good omen; (4) seeds which grow to root do best when planted during the last days of the waxing moon; (5) horse chestnut in pocket guards against sore throat, etc.
(4) Sympathy and undue interest.
The influence of the heart over the brain is well known. A physician is liable to this error when he attempts to prescribe for one of his own family. Sympathy not only warps the judgment but it may actually interfere with the accuracy of an honest observer’s perceptive powers.
(5) Inattention and a fallible memory.
These short comings are too apparent to demand discussion.