E. The conclusion must be reasonable.
After all the foregoing requirements have been met there still remains one essential. The conclusion must be reasonable. This is the ultimate test of validity. We have become so familiar with the usual course of nature that we instinctively question that which appears to run contrary thereto. Nothing occurs without an adequate cause. Upon this principle we base our judgment regarding all matters which transcend our own experience. Most of us have passed the superstitious days when the breaking of a looking glass was regarded as a sure sign that someone in the family would die before the end of the year. Even the time-honored Friday and number thirteen with their attendant superstitious disasters no longer have a large following. Scientific investigation and the present age of commercialism have crowded out superstition and put common sense in its place. The average mind is highly reasonable and requires some causal connection between the breaking of a looking glass and the death of a person. It would refuse to believe that one caused the other, or that one was the sign of the other, even though there might be a hundred instances to warrant the induction and not one to contradict it. The final requirement for an imperfect inductive argument is that it be reasonable.
SUMMARY OF REQUIREMENTS FOR AN IMPERFECT INDUCTIVE ARGUMENT
1. The number of specific instances supporting the conclusion must be sufficiently large to offset the probability of coincidence.
2. The class of persons, events, or things about which the induction is made must be reasonably homogeneous.
3. The specific instances cited in support of the conclusion must be fair examples.
4. Careful investigation must disclose no exceptions.
5. The conclusion must be reasonable.
EXERCISES
1. Are the following inductions perfect or imperfect?