Another common type of reasoning is the search for causes and results.We want to know whether cigarettes really do cause lung cancer,what causes malnutrition,the decay of teeth.We are equally interested in effects:what is the effect of sulphur or lead in the atmosphere,of staying up late on the night before an examination.
Causal reasoning may go from cause to effect or from effect to cause.Either way,we reason from what we know to what we want to find out.Sometimes we reason from an effect to a cause and then on to another effect.Thus,if we reason that because the lights have gone out,the refrigerator won’t work,we first relate the effect (lights out) to the cause (power off) and then relate that cause to another effect (refrigerator not working).This kind of reasoning is called,in short,effect to effect.It is quite common reasoning through an extensive chain of causal relations.When the lights go out we might reason in the following causal chain:lights out – power off – refrigerator not working – temperature will rise – milk will sour.In other words,we diagnose a succession of effects from the power failure,each becoming the cause of the next.
Causes are classified as necessary,sufficient,or contributory.A necessary cause is one which must be present for the effect to occur,as combustion is necessary to drive a gasoline engine.A sufficient cause is one that can produce an effect unaided (as an empty gas tank is enough to keep a car from starting),though there may be more than one sufficient cause.A contributory cause is one which helps to produce an effect but cannot do so by itself,as running through a red light may help cause an accident,though other factors must also be present.
1.What the author discussed in the previous section is most probably about ________.
A) relationships between causes and results
B) classification of reasoning
C) some other common types of reasoning
D) some special type of reasoning
2.According to the passage,to do the “effect to effect” reasoning is to reason ________.
A) from cause to effect
B) from effect to cause
C) from effect to effect and on to cause
D) from effect to cause and on to another effect.
3.A necessary cause is ________.
A) one without which it is impossible for the effect to occur
B) one of the causes that can produce the effect
C) one that is enough to make the effect occur
D) none of them
4.Your refrigerator is not working and you have found that the electric power has been cut off.
The power failure is a ________.
A) necessary cause B) sufficient cause
C) contributory cause D) none of them
5.This passage mainly discusses ________.
A) causal reasoning
B) various types of reasoning
C) classification of causes
D) the causal process