Read Online Critical thinking for Students by Roy van den Brink-Budgen - Free Book Online Page B
Authors: Roy van den Brink-Budgen
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uninvited. It was us that let it into the discussion.
Just a little diversion before we move on. When we referred to an ‘assumed inference’ above, we were in fact looking at what is technically called an implication . There was no inference drawn from the claim, but the given claim was designed such that you would draw a particular one. We could ask ‘What was implied by the claim?’ and the answer is, ‘The implication is that you should use the website’. Though the implication that you wouldn’t save money is also there, it’s in a way being jostled out of the picture by the context in which the claim appears. The advert in which it appears is not a neutral context in which claims are being presented for neutral discussion. It’s not as if Socrates is toying with the idea that he could save money on his insurance by using a price comparison website and responds with the counter-claim that he also could not.
Watch out for claims (especially evidence-claims) that just sit there with an intended implication sitting next to them. Here’s a recent evidence-claim:
TV reduces adult-child conversations.
This claim appeared in a June 2009 edition of The New York Times . The implication that is sitting next to it is not ‘so parents should have the TV on more when they’re with children’. It is, of course, the opposite. Once again, as we have seen, we’re back to the point about the significance of claims. We’ve stressed time and time again that claims have a neutral significance unless and until someone comes along and gives them a particular significance. So, an alien from a planet which has been searching for ways of getting children to talk less to adults would be thrilled by the finding and report back from New York to alien HQ that every household on the planet must have the TV on much more. Implication becomes inference when someone draws the implication.
When looking at evidence-claims, are some types less problematic than others? Let’s look at some of them.
PERCENTAGES
Percentages are often seen as particularly useful because they deal with the possible problem of the disputable significance of overall numbers. Thus, the information that, for every hour that the TV is on, there is a seven per cent decrease in the number of words that a child hears is probably more helpful than knowing that the child hears 770 fewer words. The overall number might seem more dramatically significant but the problem is knowing how significant it really is.
There can, however, be issues of significance with percentages. These are found especially when we are looking at percentages involving small numbers. Look at the next argument:
At the fifth Teenage Cancer Trust conference held in June 2008, it was reported that between 1979 and 2003, the incidence of cervical cancer had increased by 1.6 per cent per year. But the figure for those aged 15–19 was 6.8 per cent per year. These figures show that it is the increase in teenagers with the disease that is causing the overall increase. Therefore we need to have a campaign to educate teenagers about the dangers of having lots of sexual partners.
You can see that the author gives us two different percentages. Both refer to percentage changes over the period 1979–2003. In this way, they might be seen as comparable. In one important way, they are. But might there be a problem in comparing the two? The first covers cases of cervical cancer in all age groups in the UK over a 14-year period. The second covers only the 15–19 age group. This alerts us to why there might be a problem. Obviously the 15–19 age group is significantly smaller in number than that of all age groups (15 to 100+). In addition, we would expect very few 15–19 females to get cervical cancer (indeed, to get any form of cancer). And this turns out to be a devastatingly significant point. It has been calculated that a 6.8 per cent increase in cervical cancer per
Just a little diversion before we move on. When we referred to an ‘assumed inference’ above, we were in fact looking at what is technically called an implication . There was no inference drawn from the claim, but the given claim was designed such that you would draw a particular one. We could ask ‘What was implied by the claim?’ and the answer is, ‘The implication is that you should use the website’. Though the implication that you wouldn’t save money is also there, it’s in a way being jostled out of the picture by the context in which the claim appears. The advert in which it appears is not a neutral context in which claims are being presented for neutral discussion. It’s not as if Socrates is toying with the idea that he could save money on his insurance by using a price comparison website and responds with the counter-claim that he also could not.
Watch out for claims (especially evidence-claims) that just sit there with an intended implication sitting next to them. Here’s a recent evidence-claim:
TV reduces adult-child conversations.
This claim appeared in a June 2009 edition of The New York Times . The implication that is sitting next to it is not ‘so parents should have the TV on more when they’re with children’. It is, of course, the opposite. Once again, as we have seen, we’re back to the point about the significance of claims. We’ve stressed time and time again that claims have a neutral significance unless and until someone comes along and gives them a particular significance. So, an alien from a planet which has been searching for ways of getting children to talk less to adults would be thrilled by the finding and report back from New York to alien HQ that every household on the planet must have the TV on much more. Implication becomes inference when someone draws the implication.
When looking at evidence-claims, are some types less problematic than others? Let’s look at some of them.
PERCENTAGES
Percentages are often seen as particularly useful because they deal with the possible problem of the disputable significance of overall numbers. Thus, the information that, for every hour that the TV is on, there is a seven per cent decrease in the number of words that a child hears is probably more helpful than knowing that the child hears 770 fewer words. The overall number might seem more dramatically significant but the problem is knowing how significant it really is.
There can, however, be issues of significance with percentages. These are found especially when we are looking at percentages involving small numbers. Look at the next argument:
At the fifth Teenage Cancer Trust conference held in June 2008, it was reported that between 1979 and 2003, the incidence of cervical cancer had increased by 1.6 per cent per year. But the figure for those aged 15–19 was 6.8 per cent per year. These figures show that it is the increase in teenagers with the disease that is causing the overall increase. Therefore we need to have a campaign to educate teenagers about the dangers of having lots of sexual partners.
You can see that the author gives us two different percentages. Both refer to percentage changes over the period 1979–2003. In this way, they might be seen as comparable. In one important way, they are. But might there be a problem in comparing the two? The first covers cases of cervical cancer in all age groups in the UK over a 14-year period. The second covers only the 15–19 age group. This alerts us to why there might be a problem. Obviously the 15–19 age group is significantly smaller in number than that of all age groups (15 to 100+). In addition, we would expect very few 15–19 females to get cervical cancer (indeed, to get any form of cancer). And this turns out to be a devastatingly significant point. It has been calculated that a 6.8 per cent increase in cervical cancer per
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