7. “Blessed are the meek for they shall inherit the earth.”
II. Diagram, by means of circles, the syllogisms constructed under exercise I.
III. State three instances in which you have recently employed deductive argument.
IV. Write a deductive argument of not less than three hundred words.
CHAPTER III
ARGUMENT FROM CAUSAL RELATION
Arguments from causal relation are divided into three classes, I. Arguments from Effect to Cause, II. Arguments from Cause to Effect, and III. Arguments from Effect to Effect. All arguments from causal relation may be classed under one or the other of these divisions. These arguments are based upon a fact which human experience has demonstrated to be true—the fact that everything that occurs has back of it some adequate cause. In ancient times this belief in the laws of universal causation did not exist. Hence every occurrence of any importance was attributed to the commands of one of the numerous heathen gods. Instead of attributing the defeat of a general to poor management it was customary to say, “The gods decreed that this general should be defeated in war.”
We still have remnants of this belief. These remnants consist of popular superstitions, such as the supposition that Friday is an unlucky day, that the number thirteen is unlucky, that the breaking of a looking glass portends bad luck, or that the sight of a black cat in the path is sure to be followed by some disaster. Modern science has abolished most of these superstitions by pointing out the fact upon which all causal relation arguments are based, viz.—that everything that happens has back of it a reasonable cause—or in other words, if a thing is true there must be some sufficient reason for it. So well has this fact been established that, with the exception of the less enlightened members of society, the belief in the laws of causation is universal. Upon this sound basis must every argument find its ultimate justification. Even inductions and deductions may be traced to their source where the law of cause and effect will finally determine their validity. It is therefore of the utmost importance that we give careful consideration to this class of arguments. As in the case of imperfect induction, we are reasoning from the known to the unknown; from things of which we are conscious to things that are beyond the realm of our perception. We shall consider the form of these arguments and the conditions with which they must comply in order to be valid.
I. Argument from effect to cause.
The argument from effect to cause is one which relies upon an observed effect to prove the operation of an unobserved cause. Upon arising in the morning I observe that the ground which was bare the evening before is now white with snow. Therefore I reason that snow must have fallen during the night, although no snow is now falling and I have not seen any snow in the actual process of falling. The snow-covered ground is the effect which I observe and the unobserved fall of snow during the night is the only possible cause for this effect. If a friend who has not yet seen the snow disputes my assertion that there was a snowfall during the night by saying that it is too warm to snow, I may effectively establish my argument and refute his own by calling him to the window and pointing to the snow. I should point to the effect as establishing the existence of the cause. This would be conclusive evidence of the truth of my statement.
The argument from effect to cause is based upon things observed after the disputed fact. This process is called a posteriori reasoning which means reasoning from that which comes after. This is the process of reasoning employed by the detective in tracing a criminal. The detective by means of skillful observations taken after a crime is committed reasons back to the person who is guilty. The fact that the criminal has usually made an attempt to avoid leaving any traces that may be used as a basis of a posteriori reasoning makes this process a most interesting one and accounts for much of the popularity of detective stories.