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Bell Ringer. Four men went fishing. They caught six fish altogether. One man caught three, another caught two, one caught one, and one didn’t catch anything. Which man caught how many fish? What did each of the fishermen use for bait?
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Bell Ringer • Four men went fishing. They caught six fish altogether. One man caught three, another caught two, one caught one, and one didn’t catch anything. Which man caught how many fish? What did each of the fishermen use for bait? • 1. The one who caught two fish wasn’t Sammy nor the one who used worms. • 2. The one who used the flatfish didn’t catch as many as Fred. • 3. Dry flies were the best lure of the day, catching three fish. • 4. Torkel used eggs. • 5. Sammy didn’t use the flatfish.
2.8 Reasons • Reasons are expressions which tell us why something is as it is. • Primary function is to explain. • Sea levels are rising around the world because global warming is melting the polar ice caps. • Looks like an argument, can be rephrased.
Global warming is melting the polar ice caps and therefore sea levels are rising… • The previous two statements do not make the argument that sea levels are rising: they assert why sea levels are rising. • The claim that the seas are rising is not a conclusion in need of support, but a claim to fact in need of an explanation.
Compare: • Global warming must be happening because the polar ice is melting and sea levels are rising. to • Sea levels are rising around the world because global warming is melting the polar ice caps.
In the first statement, global warming is not being explained by rising sea levels: rising sea levels are being offered as grounds (or evidence) for arguing that global warming is taking place. • The phrase ‘must be’ helps us to see that the author is urging the reader to accept the claim.
Even without this clue it is quite obvious that rising could not be the cause of global warming, whereas it makes good sense to offer rising seas as evidence of global warming. • It may not be conclusive evidence, but it is supportive.
The word ‘reason’ is ambiguous, depending upon whether it is a reason why (as in explanation), or a reason for (as in an argument). • This can make it difficult to be sure whether a set of sentences is expressing an argument or giving an explanation, especially without indicator words to label the sentences.
Reasons as Premises • Premises are claims from which a conclusion is said to follow. • That it follows logically. • That if the premises are true, the conclusion must be true too.
If the conclusion does not follow from the premises, then even if the premises are true, the conclusion might be false. • A good argument is one in which the premises are true and the conclusion does follow. • The premises are reasons for believing, or agreeing with, the conclusion.
Relevance • Premise cannot be understood as a reason for a conclusion unless it is relevant to the conclusion. • Seawater is salty, so Mars is a planet! • The premise of this argument is true, and so is the conclusion.
Since the two claims are unrelated, the second claim is known as a ‘non sequitur’ because it does not follow from the premise in any logical sense of the word, even though both claims are true. • Nor does the saltiness of water explain why Mars is a planet.
Comparison • Mars is a planet since it can be seen to orbit the sun. • Its orbiting of the Sun justifies the claim that Mars is a planet. If you did not already know that Mars was a planet, the argument would give you a reason to believe it.
Summary • There are two ways in which a claim can be understood as a reason: • As grounds for drawing a conclusion. • As an explanation.
Activity • Tax rises are not vote-winners. In the last four decades, every time a government has raised taxes, their poll-ratings have fallen significantly. • Is it an argument or explanation? • Without some context, the clues are insufficient for us to work out what point the author is making.
It might be the first sentence is meant to explain why tax-raising governments have experienced a slide in the polls; or the slide in the polls may be meant as evidence that tax rises are not vote-winners. • Both make reasonably good sense. • The right answer with regard to the passage is that it is ambiguous.
The government will not raise taxes this close to a general election. The result could be very close and tax rises are not vote-winners. • It is clearly an argument. • First sentence is a prediction. The second supplies two reasons (joined by ‘and’) which can be taken as support for the prediction.
But would it not be just as accurate to say that the two reasons in the second sentence are explaining why the government will not raise taxes close to an election? • It would seem that it is both an argument and an explanation; or that the explanation is an argument.
The passage illustrates that one way of supporting a conclusion is to offer an explanation for it. By explaining it, successfully, the author also makes it more believable. • The boundary between argument and explanation is not always a clean line.
Venn Diagram Representation Argument Explanation Text
Another Example • The accused was at her desk in the office at 3 p.m. but no one reported seeing her again until after 4. That was plenty of time to get to the scene of the crime and back. • Does either sentence explain or or support the other? • There is a plausible third reading.
They are part of the same story, but aside from that they are really independent claims. • The first is that no one reported seeing the accused for an hour; the second that an hour was time to get to the crime scene and back. • If the second claim is true then it is true whether or not anyone saw the accused between 3 and 4 p.m. has nothing to do with the accessibility of the crime scene.
Any attempt to make an argument out of this passage would result in a non sequitur – the supposed conclusion does not follow from the premises. • It is a bad argument. • There is little justification for calling the passage an argument or an explanation.
Homework • Critical Reasoning • Read pp. 35-41.