Sunday, January 19, 2014

Recognising Implications: Assessing implications

Exercise:
For each of the following passages, assume that what is said in the passage is true, and
assess whether each of the responses (a) to (e) is true, false, probably true, probably false,
or whether you have insufficient information in the passage to draw any conclusion about
the statement’s truth or falsity. Write your answer – T, F, PT, PF, or II – at the end of each
of the sentences (a) to (e). You may find it interesting to compare your answers to the
exercise with someone else’s.
1 A study from Sweden reports that the incidence of skin cancer increased by 50 per
cent between 1979 and 1987. Exposure to sunlight is known to cause skin cancer in
light-skinned people. The incidence of skin cancer was found to be higher amongst
professionals than amongst manual workers – thus it was higher amongst those who
can afford to take holidays in places with very sunny climates. Twenty per cent of
skin cancer cases occurred amongst those aged between 20 and 39, although most
types of cancer are uncommon in this age group.
(Source: ‘Cancer threats all around us’, Celia Hall, The Independent, 30 March, 1993)
(a) Manual workers in Sweden have no risk of getting skin cancer.
(b) There is a lower risk of skin cancer for those aged over forty than for those aged
under forty.
(c) The increase in the incidence of skin cancer in Sweden indicates that exposure
to sunlight cannot be the only cause of skin cancer.
(d) Those aged over 40 in Sweden are more likely than the rest of the population to
take holidays in places with sunny climates.
(e) The increased incidence of skin cancer in Sweden may be due to an increase in
the numbers of people taking holidays in places with sunny climates.
2 Nearly 600 people, most of whom had an inflated sense of their own safety as car
drivers, took part in a study which investigated ways of getting people to drive more
safely. The drivers were asked to fill in a questionnaire detailing an imaginary
accident which they had caused and which had serious repercussions, such as the loss
of a child’s life. They had to write a description of the consequences, and imagine
the subsequent guilt, lack of confidence or inability to drive again. Before the study,
50 per cent of the group said they would be prepared to drive at over 80 miles per
hour on a motorway. After completion of the questionnaire, this figure fell to
27 per cent. The group most likely to overestimate their driving skills and safety were
young men.
(a) Most drivers have an inflated sense of their own safety.
(b) Some drivers who overestimate their driving skills tend to drive too fast.
(c) People with only a few years driving experience do not overestimate their skills.
(d) Forcing drivers to imagine that they have had a serious road accident may make
them drive more responsibly in the future.
(e) Imagining that one has caused a serious accident has the undesirable effect of
reducing one’s confidence as a driver.
3 A technique for inducing phantom sheep pregnancies has been developed to address
the problem of what to do with the million lambs born each year to mothers that for
one reason or another cannot breast-feed them. Fostering is notoriously difficult
because a ewe quickly forms a bond with its own lamb and rejects all others. Farmers
are forced to rear orphaned lambs themselves, and lack of maternal contact can cause
behaviour abnormalities. Gently stretching the neck of the cervix with two fingers
sends nerve signals to the animal’s brain that mimic those produced in labour. The
sheep believes it has given birth to a second lamb. The orphaned lamb can then be
introduced to its new mother with an 80 per cent chance that it will be accepted.
(a) A ewe which gives birth to two lambs from one pregnancy will form bonds with
both lambs.
(b) A ewe will reject her own lamb if she is introduced to an orphaned lamb.
(c) An orphaned lamb may fail to develop normal behaviour if it is not fostered by a
ewe.
(d) An orphaned lamb needs maternal contact in order to grow to adulthood.
(e) The formation of a bond between a ewe and a lamb can occur even if the ewe is
not the mother of the lamb.
4 Dipping of sheep protects the animals from scab and blowfly attacks. Leather manufacturers
report that since sheep dipping ceased to be compulsory last year, 60 per
cent of British sheepskins have been found to have damage from these parasites. But
there are worries that sheep dips can cause health problems for farmers who use
them. The Veterinary Products Committee examined medical evidence on 266 cases
of people who believed that their influenza-like symptoms were caused by exposure
to sheep dip. They found a possible link to sheep dip in only fifty-eight of these cases,
and of these fifty-eight, only three had worn protective clothing while using the dip.
The long-term effects of low level exposure to sheep dip are not known. However,
because of concerns about safety, the Ministry of Agriculture has introduced legislation
requiring farmers who use sheep dips to have a certificate of competence.
(a) Scab and blowfly cause distress to sheep.
(b) There is no evidence that there may be a link between influenza-like symptoms
and the use of sheep dips.
(c) Protective clothing prevents sheep dip from damaging farmers’ health.
(d) Low level exposure to sheep dip is known to be dangerous enough to justify
banning the use of the dip.
(e) Sheep dips need to be handled with great care because they present a risk to the
health of farmers who use them.
5 In 1963 Stanley Milgram investigated whether people would obey orders when they
were asked to do something which conflicted with their moral attitudes. Volunteers
for his experiment were made to believe that if they pressed a button, they would
administer an electric shock to a ‘learner’ seated behind a screen, who was giving
answers in a memory test. The subjects were ordered to press the button every time
the ‘learner’ gave a wrong answer. The ‘learner’ did not receive a shock, but cried out
as if in pain each time the button was pressed. Contrary to the predictions of psychologists,
most of the subjects in the experiment continued to obey the order to press
the button, even though they expressed anxiety about doing so.
(a) The volunteers for the experiment were not typical of people in general.
(b) Those who took part in the experiment wanted to avoid inflicting pain.
(c) There is no evidence that people will obey orders when asked to do something
they consider wrong.
(d) Those who took part in the experiment did not believe that the ‘learner’
suffered any pain.
(e) Prior to the experiment, psychologists had thought that most people would
refuse to obey an order to give electric shocks.
6 The red squirrel has been pushed out of most of its territory in Britain by the North
American grey squirrel which was introduced at the end of the nineteenth century.
This is probably because grey squirrels can digest acorns (an ability that evolved in
their native woodlands where oak trees are common), whereas red squirrels, which
normally live in conifer woods, eat acorns only reluctantly, and lose weight on a diet
that consists solely of acorns. When red squirrels do not have to compete with grey
squirrels, hazelnuts are a major item of their diet throughout the winter. Grey
squirrels eat acorns only after all the available hazelnuts have been consumed. Where
grey squirrels are plentiful, they have often eaten the entire crop of hazelnuts by
October.
(a) Red squirrels are not found in North America.
(b) Grey squirrels will eat anything that red squirrels eat.
(c) Red squirrels would thrive in woodland that contained only oak trees.
(d) Grey squirrels would not survive in woodland in which there were no
hazelnuts.
(e) In woodland in which both acorns and hazelnuts are found, grey squirrels are
more likely to thrive than are red squirrels.
ANSWERS:

1 (a) Probably false: The passage states that the incidence of skin cancer is higher amongst
professionals than amongst manual workers, which suggests that there are some cases
amongst manual workers.
(b) Insufficient information: If 20 per cent of cases occur amongst those aged 20 to 39, and
80 per cent amongst over 40s (though it may be less than 80 per cent, because some cases
may occur amongst under 20s), it looks more likely that the risk is greater for over 40s. But
we do not have enough information to conclude that (b) is false, first because it makes a
general claim, and we have figures only about the incidence in Sweden, and second because
we do not know about any differences in lifestyles of the two age groups in Sweden which
may account for the greater percentage of cases amongst the over 40s.
(c) False: The increased incidence of skin cancer in Sweden could be caused by exposure
to sunlight, since more people from Sweden may be taking holidays in sunny countries. Of
course, it may be true that exposure to sunlight is not the only cause of skin cancer, but it
is false that the figures from Sweden indicate this.
(d) Insufficient information: Although we are told that only 20 per cent of cases occur in the
20 to 39 age group, and that exposure to sunlight is a significant cause of skin cancer, we
do not know whether the higher number of cases amongst over 40s is attributable to
greater exposure to sunlight for this group, or to a greater tendency for older people
to succumb to skin cancer, even given equal exposure to that of younger people.
(e) True: We can conclude that the increased incidence of skin cancer in Sweden may
be due to an increase in numbers holidaying in sunny countries. In answering ‘true’ to
(e), we are not concluding that this is the cause. (e) merely states tentatively that it
may be.
2 (a) Insufficient information: We are told only about the sample of 600 drivers. Even if most
of them had an inflated sense of their own safety as car drivers, this information cannot
support the claim that most drivers have an inflated sense of their safety. The drivers in
this sample may not have been representative of drivers in general. They may have been
chosen because of their unusual attitudes.
(b) Probably true: If most of the group overestimate their driving skills, then some of the 50
per cent who said they would drive at over 80 mph on a motorway must also overestimate
their driving skills. Assuming that 80 mph is too fast, and that the drivers do as they say,
then these drivers tend to drive too fast on motorways. Since these assumptions are not
unreasonable, it is probably true that some drivers who overestimate their skills tend to
drive too fast.
(c) Probably false: We are told that those most likely to overestimate their driving skills are
young men. Since young men are likely to have had only a few years’ driving experience, it
is probably false that those with only a few years’ driving experience do not overestimate
their driving skills.
(d) True: The study demonstrated that forcing drivers to imagine that they had caused a
serious accident made some of them change their judgement about the speed at which
they would be prepared to drive. Assuming that the effect on their attitudes is long-term,
and that they act in accordance with this changed judgement, some of them will drive
more responsibly, with respect to speed, in the future. So it is true that imagining the
accident may make them drive more responsibly in the future.
(e) Insufficient information: We are told that the drivers were asked to imagine the lack of
confidence they might experience if they caused a serious accident. But this does not imply
that they actually lost confidence in their driving as a result.
3 (a) Probably true: Although the passage refers to a ewe forming a bond with ‘its own lamb’,
this use of the singular noun does not suggest that a ewe can form a bond with only one of
its own lambs. The statement that the ewe ‘rejects all others’ is best understood as meaning
that she rejects all except her own lambs.
(b) Insufficient information, or probably false? Strictly speaking we do not have enough
information in this passage to conclude either that a ewe will or that she will not reject her
own lamb if she is introduced to another lamb. However, given a few assumptions, we can
conclude that (b) is probably false. First, if the ewe really believes she has given birth to
another lamb, then presumably she can form bonds with both her own and the orphaned
lamb in the same way that she could (we have assumed above) form bonds with both her
own twin lambs. Second, unless the farmers are using this technique only with ewes whose
own lambs have died shortly after birth, there would be no point in using the technique at
all if it resulted in an orphaned lamb being accepted by the foster mother, whilst her own
lamb was rejected.
(c) True: We are told that lack of maternal contact can cause behaviour abnormalities.
(d) False: We are told that farmers do rear orphaned lambs themselves. Such lambs may
have behaviour abnormalities, but can nevertheless grow to adulthood.
(e) True: There is an 80 per cent chance of a ewe accepting, and thus of forming a bond
with, an orphaned lamb, if the farmer uses the technique of fooling the ewe into thinking
she has given birth to another lamb.
4 (a) Insufficient information: The passage makes it clear that scab and blowfly attacks cause
damage to sheepskins. This may be sufficient reason for farmers to want to use sheep dip.
Without further information, we cannot tell whether these parasites cause distress to sheep.
(b) False: There is some evidence of a possible link in fifty-eight of the cases examined.
(c) Insufficient information: Three of the people whose symptoms may have been caused by
using sheep dip were wearing protective clothing. If these three people’s symptoms were
definitely caused by using sheep dip, then we could conclude that the clothing does not
prevent damage to health when using sheep dip, and thus that (c) is false. But we do not
know whether their symptoms were definitely caused by the use of the sheep dip.
(d) False: We are told that it is not known what the effects of exposure to sheep dip are.
Even though we must conclude that (d) is false, this is not the same as saying that there is
no justification for banning the use of sheep dip. Some people might argue that if there is
any potential risk to health, its use should be banned.
(e) Probably true: There is some evidence of a potential risk, and the Ministry of Agriculture
is sufficiently concerned to ensure that sheep dips are handled only by those with a
certificate of competence.
5 (a) Insufficient information: We are not told anything about them, except that they were
volunteers.
(b) Probably true: We are told they expressed anxiety about pressing the button (but
probably true rather than true, because their anxiety may have been due to the thought that
the shock could be fatal, not merely painful).
(c) Probably false: The experiment provides evidence that these subjects obeyed orders
even though they expressed anxiety about doing so. You may have judged (c) to be definitely
false on these grounds, and that would be a reasonable answer given an assumption
that the anxiety arose from a feeling that they were doing something morally wrong.
(d) Probably false: The subjects probably did believe that the ‘learner’ suffered pain
since they presumably heard the ‘learner’ cry out, and since they expressed anxiety about
pressing the button.
(e) True: The passage tells us that the result of the experiment, i.e. that the subjects obeyed,
was contrary to the predictions of psychologists.
6 (a) Insufficient information: We are told only that red squirrels are found in Britain, and
that grey squirrels are not native to Britain.
(b) Insufficient information: We are told that grey squirrels eat hazelnuts and acorns, and
that red squirrels eat hazelnuts, but red squirrels may eat other nuts that grey squirrels do
not eat.
(c) False: the passage states that red squirrels lose weight on a diet that consists solely of
acorns.
(d) Probably false: We are told that grey squirrels can digest acorns, so they may well survive
without hazelnuts.
(e) True: Where there are grey squirrels, all the hazelnuts will have been eaten by October,
and the grey squirrels will then be able to live well on acorns, whereas the red squirrels will
not have hazelnuts to eat throughout the winter.

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