Skill 8:  Keeping Logical Consistency

Inclear and consistent arguments, the reasons support the conclusion that theauthor draws from them. When evaluating an argument, we need to check whetherthe reasons given by the author do indeed support the conclusion. In other wordswe need to check that the argument adds up. When we do this we are checking forlogical consistency.

Sometimesauthors lose track of their own arguments and draw a conclusion that does notfollow from the reasons given. Sometimes, there may not be good reasons for theargument and we may feel the author is clutching at straws in the hope we won’tnotice the lack of logic. For Example 1 below, consider why the reason does notsupport the conclusion.

Example 1:

Therewas a murder near the station last night. There are always young lads hangingaround there. One of them probably did it. The local council should ban youngpeople from hanging around the station.

Inthe example above, the conclusion is that young people should be banned fromhanging around the station. The reason given to support the conclusion is thatone set of young people is often found near a station where a murder tookplace. This reason does not support the conclusion because there is nothing toshow that:

---those young people did commit the murder;

---even if they did so, other young people would do the same;

---a general ban on young people would prevent future murders.

Thisis partly a question of lack of evidence. However, it is also faulty reasoning,as the conclusion does not follow from the reasons presented. An alternativeconclusion might have been that if the young people were in the vicinity whenthe murder took place, they might have seen or heard something that would helpto solve the case. For Example 2, see if you can identify the conclusion andthe reasons given to support it before reading on.

Example 2:

Behavioris better in schools in rural areas than in inner city schools. Childrenbrought up in the country have more responsibility for contributing to thefamily livelihood and care for vulnerable animals. This fosters a more matureattitude and a respect for life in general. Children in inner city schoolsoften have more material possessions but value them less. They show lessrespect for parents and teachers. Children from the cities should be sent toschool in rural schools. This would lead to more children who are respectfuland well behaved.

Inthis case, the conclusion is provided in the last two lines: if children weresent from city to country schools, their attitude and behavior would improve.The main reason given is that children in rural areas have better behavior andattitudes.

However,the alleged better behavior of children in the countryside is attributed to theresponsibilities they have at home, not to the schools themselves. As citychildren would not gain such responsibilities simply by going to rural schools,it does not follow logically that moving school would lead to a change in theirbehavior. The reasons provided in the example provide better grounds for analternative conclusion: that the behavior of city children might improve ifthey were given more responsibilities.

Activity:  Read through the following passages and decidewhether each is consistent or inconsistent. Give your reasons.

Passage 1:

RealityTV is not delivering what the public wants. Too many programmers are cheaplymade, turning a camera on the experiences of ordinary people who are duped intowanting their short period of fame. As a result, investment in quality programsis declining. There is much less variety on television. The promise of choiceheralded by digital TV has not materialized. Far from exercising choice, lastnight almost the whole nation switched on to watch the final episode of thelatest reality show. What has happened to television drama, good comedyprograms and well-researched documentaries?

Passage 2:

Trainersshould discourage sportspeople from taking performance enhancement drugs asthese can have serious effects upon their health. Some of these drugs haveresulted in distorted body shapes, skin conditions, and increased aggression.The long-term effects of some of these drugs are unknown. On the other handsome individuals with conditions such as asthma need medication which containsthose drugs. For them, taking the drugs may be more beneficial than not takingthem. Therefore it would be wrong to ban performance enhancement drugsaltogether.

Passage 3:

Thedeepest parts of the oceans are known as the abyssal zone. The bathyal zonewhich is that part of the abyssal zone found on the continental shelf, is toodeep even for light to penetrate. Despite this absolute darkness, animal lifestill thrives there. Humans form part of the animal kingdom. As animals survivein the bathyl zone, this proves that we do not need light in order to survive.

Passage 4:

Itis impossible to find any place where there is absolute silence. Now,everywhere you go there are mobile phones ringing, people shouting, car hornsblaring, music pouring from ghetto-blasters or ringing out in its irritatingtinny tomes from personal stereos. There is no place where you can go that doesnot have a sound of some kind breaking the silence. Noise pollution isdefinitely on the increase.

Passage 5:

Computerscan now compete with humans in complex games such as chess and beat them. Thiswas believed impossible until the end of the last century. Since then, computermemories have become ever larger and faster. Now, very large memories can bestored in tiny spaces. Computers do not feel emotions, a faculty which isneeded in order to empathize with other people. Nonetheless, computers will oneday be able to out-perform humans at everything.

Passage 6:

Thecountryside is a lost cause. The green fields and woodlands known as “greenbelts” that surround our cities are essential to maintain the beauty of thecountryside. Over 8 per cent of the countryside is now built up. Green beltsare ever more essential to provide lungs to our growing cities, helping them to“breathe”. Unfortunately, the countryside is rapidly disappearing as theextensive building of new homes stretches out of the cities. Before long itwill be gone and once that happens, it will be difficult, if not impossible,ever to restore the complex ecosystems of lost woodlands and hedgerows.