Logical Reasoning: Evaluating Arguments, Assumptions, Flaws and Predicting Outcomes

This is the first chapter of the Humanities and Social Sciences (XH) paper for Section XH0.4 of XH0 Reasoning and Comprehension, the part every XH candidate answers. It answers the heading “Section XH0.4: Logical Reasoning — Thinking critically to evaluate or to predict an argument, identify the main and supporting arguments, predict outcomes etc.” Every item in this section hands you a short argument and asks you to do something to it. This chapter teaches the anatomy of an argument (premises, conclusion, assumption), how to separate the main conclusion from intermediate conclusions and counter-considerations, how to find and test assumptions with the negation test, how to strengthen, weaken and evaluate a claim, the common flaws in reasoning, and how to predict outcomes, match logical form and resolve an apparent paradox. Every worked question carries its argument inside the stem, so the reader needs nothing from outside it.

1. The anatomy of an argument: premises, conclusion and assumption

An argument is a set of statements in which some, the premises, are offered as reasons for another, the conclusion. Not every passage is an argument: a description or a list of facts has no conclusion, and the first job in any logical-reasoning item is to decide whether there is one and what it is. A usable test is to ask of each statement, “is this being supported, or is it supporting something?” The statement that everything else is there to support is the conclusion. Indicator words help: therefore, thus, hence, so and it follows that usually introduce a conclusion, while because, since, for and given that usually introduce a premise. The order in the passage does not matter; the conclusion may come first, last or in the middle.

🧠 The ‘why?’ test
Put ‘why?’ after a statement. If another statement in the passage answers it, the first is a conclusion (or an intermediate one) and the answering statement is a premise. A statement that nothing answers, and that answers nothing else, is background.

Between the premises and the conclusion there is almost always a gap that the writer does not state. The unstated link is the assumption. In “The café is always crowded, so its food must be good”, the premise is the crowd, the conclusion is the quality of the food, and the assumption is that people come for the food. An argument is strong when its assumptions are safe and weak when they can be doubted, so nearly every item in this section is really a question about the gap: find it, test it, fill it, break it, or copy its shape.

2. Main conclusion, supporting statements and counter-considerations

The statements of a real argument play different roles, and the exam often asks you to name one. The main conclusion is what the whole argument is trying to establish. An intermediate conclusion is supported by earlier statements and then itself used to support the main conclusion, so a chain A, therefore B, therefore C has B in the middle. Premises are the evidence or reasons. Background sets the scene without supporting anything. A counter-consideration is a point that cuts against the conclusion, usually flagged by ‘admittedly’, ‘of course’ or ‘some argue’, and usually followed by a reply that explains why it does not change the verdict.

A worked case. “Our village needs a new bridge. The old one cannot carry heavy vehicles, so farmers must drive eight kilometres round to reach the market. Admittedly a new bridge is expensive, but the trade lost each year is worth more than the cost.” The main conclusion is the opening claim about the need for a bridge. The inability of the old bridge to carry heavy vehicles is a premise, and the eight-kilometre detour is an intermediate step that follows from it. ‘A new bridge is expensive’ is the counter-consideration, and the last clause is the reply that restores the conclusion.

Roles of statements in an argument
RoleWhat it doesUsual signal
Main conclusionThe claim the whole argument exists to supporttherefore, thus, should, must
Intermediate conclusionSupported by premises, then supports the main conclusionso, which means that
PremiseGives evidence or a reasonbecause, since, given that
Counter-considerationConcedes a point against the conclusionadmittedly, of course, some argue
BackgroundSets the scene; supports nothingIn recent years, historically
⚠️ The striking statement is not always the conclusion
A vivid example, a statistic, or the sentence that comes last is not the conclusion merely for being memorable. Ask what each statement is there for. A main-conclusion option that repeats a single premise is too narrow, and one that claims more than the argument proves is too broad.

3. Assumptions: necessary and sufficient, and the negation test

A necessary assumption is one the argument cannot do without: if it were false, the conclusion would collapse. A sufficient assumption is one that, if added, would guarantee the conclusion. Wording such as “the argument depends on” or “requires” asks for the first; “if assumed, allows the conclusion to be drawn” asks for the second. The negation test checks necessity: negate the candidate, and if the argument then fails, the candidate was necessary.

Worked example. Argument: “Sales rose after the new logo appeared, so the logo raised sales.” Candidate one: “Nothing else that happened around the same time accounts for the whole of the rise.” Negated, it reads “something else around that time does account for the whole of the rise”, and the argument now has no support, so the candidate is necessary. Candidate two: “The logo is attractive.” Negated, the logo could still have raised sales by making the brand easier to recognise, so the argument survives and the candidate is not necessary.

  • Causal arguments assume that no other factor explains the effect and that the cause did not follow from the effect.
  • Sample arguments assume that the group studied represents the group about which the conclusion is drawn.
  • Analogy arguments assume that the two cases are alike in the respects that matter.
  • Plans and predictions assume that the plan can be carried out, will work as intended, and will not be defeated by a side effect or by a change in conditions.
⚠️ Necessary assumptions are modest, sufficient ones are strong
A necessary assumption usually says ‘at least some’ or ‘not wholly’, because the argument needs only a small foothold. An option that says ‘all’, ‘every’ or ‘only’ is therefore probably too strong to be necessary, however much it would help the argument. Also reject options that are merely true, merely interesting, or about enjoyment when the conclusion concerns learning.

4. Strengthening, weakening and evaluating an argument

A new fact helps or hurts an argument only by touching its gap. A strengthener makes the assumption more likely to be true; a weakener makes it less likely. Whether the new statement is true in itself is not the issue, since the question says “if true”. What matters is direction and relevance: a fact can be accurate, interesting and entirely irrelevant. An evaluate question asks what you would most want to find out: the right answer is a question whose answer, one way, would help the argument and, the other way, would hurt it.

What strengthens and what weakens each kind of argument
Kind of argumentWeakened byStrengthened by
Causal: A came before B, so A caused BAnother cause, reverse causation, or coincidenceRuling those out; a control group; a plausible mechanism
Sample: some are X, so all are XA sample that is unrepresentative, self-selected or smallA large, random sample drawn from the whole group
Analogy: X is like Y, so what holds of Y holds of XA relevant difference between X and YFurther relevant similarities
Plan or prediction: it will workAn obstacle, a side effect, or past failure of similar plansRemoval of the obstacle; past success of similar plans

Take the argument “People who own a dog report fewer sleep problems, so owning a dog improves sleep.” It is causal, so look for the three standard breaks. Another cause: dog owners may be more active in general. Reverse causation: people who already sleep well may be the ones who take on a dog. Coincidence: the pattern may vanish in a larger group. A finding that supports any one of these weakens the conclusion; a finding about, say, walking length actually supports a mechanism, so it strengthens it.

🎯 Why a comparison group is the most useful thing to ask for
A rise after a change is the oldest causal trap. The strongest rival explanation is nearly always that the same rise happened anyway: in similar places without the change, or in the same place before it. That is why a comparison group is the most useful thing to ask for when asked what would help evaluate a causal claim.

5. Flaws in reasoning

A flaw question asks what is wrong with the way the argument gets from its premises to its conclusion. The remedy is to describe the move the argument makes and then ask whether that move is ever safe. The names matter less than the description: if you can say in plain words what the argument takes for granted that it cannot, you can usually recognise the option that says the same thing in technical form.

Common flaws and their shape
FlawWhat the argument doesPlain-words test
Correlation taken as causeMoves from ‘go together’ to ‘one causes the other’Could a third factor, or the reverse, explain it?
Hasty generalisationDraws a broad claim from a few or unrepresentative casesIs the sample like the whole?
Part and wholeAssumes what is true of each part is true of the whole, or the reverseDoes a team of good players make a good team?
Necessary taken as sufficientReverses a conditional: from ‘if P then Q’ and Q concludes PCould Q hold without P?
Attack on the personRejects a claim by pointing at who made itDoes the fault bear on the claim?
Appeal to popularityTreats widespread belief as proof of truthDo many believers show it is true?
False dilemmaOffers two options as if no others existIs there a third course?
Circular reasoningUses the conclusion, reworded, as a premiseDoes the premise say the same as the conclusion?
⚠️ A bad argument can have a true conclusion
A flaw question is about the support, not the verdict. An argument may reach a conclusion that happens to be true and still be flawed, because its premises do not establish it. Do not choose or reject an option because you agree or disagree with where the argument ends.

6. Predicting outcomes, parallel reasoning and resolving a paradox

A prediction item gives information and asks what follows or what is most likely. Two kinds appear. In a chain, conditionals link up (if the river is high the road closes; if the road closes the buses divert), so a high river forces the diversion; only forced outcomes count, and an outcome that needs a new fact is wrong. In a likelihood item you reason from a stated mechanism to the most probable result. Worked example: bread sells better in the cold, a cold spell is coming, and the bakery bakes a fixed batch that already sells out by noon. Demand rises while supply stays fixed, so the bread will sell out earlier and some demand will go unmet. Unsold bread would need demand to fall, and a price rise needs a fact that was never given.

Parallel reasoning asks you to find the argument with the same logical form. Strip away the topic and keep only the skeleton. “Every A has B; this one lacks B; so this one is not A” has a different skeleton from “Every A has B; this one has B; so this one is A”, however similar the subject matter. Match three things: the type of rule (all, most, some, none), the move (affirming or denying), and the direction of the conclusion (positive or negative). An option that shares the topic but differs in any of these is a decoy.

A paradox item sets two facts that seem to clash and asks which statement best explains how both can be true. The explanation almost always reveals a hidden difference, in the group, the place, the time or the thing measured, or introduces a third factor. Worked example: a charge on vehicles entering a city centre cuts traffic inside the zone, yet bus journey times do not improve. If most of the delay arises outside the zone, where drivers avoiding the charge have increased traffic, both facts hold. An option that restates one fact, or explains only one of them, does not resolve the clash.

🧠 Four questions to ask of every logical-reasoning item
What is the conclusion? What is the evidence? What gap sits between them? What exactly is the question asking me to do to that gap: find it, fill it, widen it, copy its shape, or explain around it? Naming the task before reading the options stops the options from steering you.

Key takeaways

  • An argument is premises offered for a conclusion; find the conclusion with the ‘why?’ test and indicator words, and remember that the order in the passage does not decide it. Between the premises and the conclusion sits an unstated assumption, and most items are questions about that gap.
  • Separate the main conclusion from intermediate conclusions, premises, background and counter-considerations; the main conclusion is what everything else is there to support, and a conceded point is not the author’s own.
  • A necessary assumption passes the negation test, because negating it wrecks the argument, and is usually modest (at least some, not wholly); a sufficient assumption is strong enough to guarantee the conclusion. Reject options that are only true, interesting or off-topic.
  • A strengthener makes the assumption likelier and a weakener makes it less likely; for causal claims the standard weakeners are another cause, reverse causation and coincidence, and for sample claims an unrepresentative sample. To evaluate, ask for the fact that would swing the argument either way.
  • Describe a flaw in plain words before reading the options: correlation as cause, hasty generalisation, part and whole, necessary as sufficient, attack on the person, popularity, false dilemma and circularity. A flawed argument can have a true conclusion.
  • Predictions count only forced or best-supported outcomes, never ones that need a new fact; parallel reasoning matches the logical form, not the topic; a paradox is resolved by a hidden difference or a third factor that lets both facts hold.

Practice questions (18)

Attempt each one before opening the answer. Every explanation names the tempting wrong option as well as the right one, because that is where marks are lost.

  1. Read the argument. “The council should extend the library’s opening hours. Many students work during the day and can only study in the evening, and the library is the only free quiet place in the neighbourhood.” Which statement is the main conclusion of the argument?

    1. The council should extend the library’s opening hours
    2. Many students can only study in the evening because they work by day
    3. The library is the only free quiet place in the whole neighbourhood
    4. Students who work by day should receive public support for their studies
    Show answer

    Answer: A — The council should extend the library’s opening hours

    The recommendation that the council extend the opening hours is what the two later statements are offered to support, so it is the main conclusion. The statements about evening study and the only free quiet place are premises. The claim about public support for working students appears nowhere in the argument, so it is out of scope.

  2. Read the argument. “The app’s crash rate has fallen by half since the update. A lower crash rate means users abandon the app less often. So the update has made it easier to keep users. The team should therefore keep the update’s changes in the next release.” Which statement is the intermediate conclusion, that is, a statement supported by earlier ones that in turn helps to support the main conclusion?

    1. The app’s crash rate has fallen by half since the update
    2. The update has made it easier to keep users
    3. The team should keep the update’s changes in the next release
    4. Users abandon the app less often when its crash rate is lower
    Show answer

    Answer: B — The update has made it easier to keep users

    The statement that the update has made it easier to keep users is reached from the two earlier statements (crashes have halved; fewer crashes mean fewer departures) and then supports the recommendation, so it is the intermediate conclusion. The recommendation is the main conclusion, and the two earlier statements are premises that nothing in the argument supports.

  3. A school principal argues: “Since we introduced the new reading programme, our pupils’ average reading score has risen. So the programme is working.” On which assumption does the principal’s argument depend?

    1. Every pupil’s reading score rose after the programme began
    2. The new programme costs less to run than any of the other reading programmes that the district’s schools could have chosen
    3. The rise in the average score was not caused entirely by something other than the programme
    4. No other school in the district has introduced a reading programme of its own
    Show answer

    Answer: C — The rise in the average score was not caused entirely by something other than the programme

    To move from a rise after the programme to an effect of the programme, the principal needs the rise not to be wholly due to something else, such as an easier test; if it were, the programme would be doing nothing. A rise in the average does not require every pupil’s score to rise, cost is not part of the claim, and what other schools do does not decide whether this programme works.

  4. A city planner argues: “A protected cycle lane on Mill Road will reduce car traffic there, because commuters will switch from driving to cycling.” Which of the following, if true, most strengthens the planner’s argument?

    1. Mill Road is one of the oldest roads in the city, and it was widened twice during the last century to carry the growing number of cars that use it
    2. Cycle lanes built in other cities have often cost more than their planners first estimated
    3. A number of commuters on Mill Road already travel to work by bus rather than by car
    4. A survey finds that most Mill Road drivers live within easy cycling distance of work and say they would cycle if a protected lane existed
    Show answer

    Answer: D — A survey finds that most Mill Road drivers live within easy cycling distance of work and say they would cycle if a protected lane existed

    The argument assumes that enough drivers are both able and willing to switch. Evidence that most drivers live within easy cycling distance and say they would cycle with a protected lane supports that assumption directly. The road’s age and cost overruns elsewhere do not bear on whether traffic will fall, and commuters who already take the bus are not drivers who would switch, so they add nothing.

  5. Researchers found that people who own a dog report fewer sleep problems than people who do not. They conclude that owning a dog improves sleep. Which of the following findings would most seriously weaken this conclusion?

    1. People who already sleep well are more likely to take on the responsibility of looking after a dog
    2. Dog owners in the study reported walking for a longer time each day than non-owners did
    3. Many dog owners in the study said that they had researched different breeds very carefully before choosing which dog to buy
    4. The study included volunteers from several different towns and several different age groups
    Show answer

    Answer: A — People who already sleep well are more likely to take on the responsibility of looking after a dog

    If good sleepers are the ones who take on a dog, the arrow of cause may run from sleep to dog ownership rather than the other way round, which undermines the conclusion. Longer daily walks would offer a way in which owning a dog could improve sleep, so they strengthen the conclusion. Careful choice of breed is irrelevant to the link, and volunteers drawn from varied towns and ages, if anything, make the sample more representative.

  6. A clerk reasons: “No application is approved unless the applicant has submitted both forms. Neha has submitted both forms. Therefore Neha’s application has been approved.” Which of the following best describes the flaw in this reasoning?

    1. It draws a general rule about all applicants from the single case of Neha
    2. It treats a condition that is required for approval as if it were enough to guarantee approval
    3. It infers that submitting the forms caused the approval from the order in which events happened
    4. It reaches a conclusion that contradicts one of its own premises about the forms
    Show answer

    Answer: B — It treats a condition that is required for approval as if it were enough to guarantee approval

    The rule says that submitting both forms is necessary for approval, not that it is sufficient; Neha may still lack some other requirement, so the conclusion does not follow. The argument does not generalise from Neha to all applicants, it says nothing about the order of events or about causes, and its conclusion contradicts none of its premises.

  7. A publisher argues: “The new edition of our textbook contains twice as many worked examples as the old edition. Students learn more from worked examples than from explanations alone. So students who use the new edition will learn more than students who used the old one.” Which of the following is an assumption on which the argument depends?

    1. Students enjoy working through examples more than they enjoy reading explanations
    2. No other textbook currently available on the market contains as many worked examples as the new edition of this book does
    3. The new edition has not lost anything else that helped students learn as much as the added worked examples help
    4. Students who used the old edition generally found it difficult to follow
    Show answer

    Answer: C — The new edition has not lost anything else that helped students learn as much as the added worked examples help

    The conclusion is that the new edition teaches more overall, which holds only if the added examples are not cancelled out by a loss elsewhere; if something equally helpful was removed, the net gain could vanish, so the assumption is necessary. Enjoyment is not the same as learning, the conclusion makes no comparison with other books, and how difficult the old edition seemed is not needed.

  8. Read the information. A bakery sells more bread when the weather is cold, because people eat more bread in cold weather. A cold spell has been forecast for next week. The bakery plans to bake its usual number of loaves each day, and on ordinary days its bread is sold out by noon. If this information is accepted, which prediction for next week is best supported?

    1. Some of the bread will probably be left unsold at the end of each day
    2. The bread will sell out at about its usual time, because the number of loaves baked stays the same
    3. The bakery will be forced to raise its prices immediately, because the demand for its bread has risen so sharply
    4. The bread will probably sell out earlier than usual, so the bakery may lose sales it could have made
    Show answer

    Answer: D — The bread will probably sell out earlier than usual, so the bakery may lose sales it could have made

    Demand is expected to rise while supply stays fixed, and the bread already sells out by noon, so it should sell out earlier and some demand will go unmet. Unsold bread would need demand to fall, selling out at the usual time would ignore the rise in demand (the same supply runs out faster when demand is higher), and a price rise is not forced because nothing in the information says the bakery will or must change its prices.

  9. Consider this reasoning. “Anyone who qualifies for the final must have won at least two heats. Asha did not win two heats. So Asha does not qualify for the final.” Which of the following reasonings is most similar in its logical structure?

    1. Every employee who is promoted has completed the training. Ravi has not completed the training. So Ravi will not be promoted.
    2. Every employee who is promoted has completed the training. Ravi has completed the training. So Ravi will be promoted.
    3. Some employees who are promoted have completed the training. Ravi has not completed the training. So Ravi will not be promoted.
    4. Employees who complete the training are usually promoted. Ravi has not completed the training. So Ravi will not be promoted.
    Show answer

    Answer: A — Every employee who is promoted has completed the training. Ravi has not completed the training. So Ravi will not be promoted.

    The original takes a rule of the form ‘everyone who is X has Y’, finds a person lacking Y, and concludes that the person is not X. Only the reasoning about promotion that denies the requirement and concludes a negative outcome from an ‘every’ rule does the same. The reasoning that affirms the requirement and concludes the outcome reverses the direction; the one resting on ‘some’ cannot support a conclusion about a particular person; and the one whose rule runs from training to promotion with ‘usually’ has a different rule and a weaker strength.

  10. Read the information. Since a city introduced a charge on vehicles entering its centre, traffic inside the charging zone has fallen by a fifth. Yet buses crossing the city take as long as they did before. Which of the following, if true, best explains why bus journey times have not improved?

    1. The charge raises a large sum each year, and the city has spent most of that money on installing new road signs across the centre
    2. Most of the delay to buses arises on roads outside the charging zone, where traffic has increased as drivers avoid the charge
    3. Most drivers who enter the charging zone pay the charge by telephone rather than online
    4. Bus drivers in the city report that they are satisfied with their working conditions
    Show answer

    Answer: B — Most of the delay to buses arises on roads outside the charging zone, where traffic has increased as drivers avoid the charge

    If the delay to buses arises mainly outside the zone, where traffic has grown because drivers avoid the charge, then traffic inside the zone can fall without helping buses, so both facts hold. How the money is spent, how drivers pay, and how bus drivers feel about their conditions have no bearing on journey times, so none of them explains the apparent clash.

  11. Read the argument. “Cities that invest in public parks tend to have lower crime rates. Our city should therefore build more parks. The cost will be high, but it is outweighed by the benefit to public safety.” What role does the sentence ‘The cost will be high, but it is outweighed by the benefit to public safety’ play in the argument?

    1. It states the main conclusion of the argument in its final and most fully developed form
    2. It supplies the evidence that public parks lower crime
    3. It answers a likely objection to the conclusion that more parks should be built
    4. It rejects the claim that cities with parks have lower crime rates
    Show answer

    Answer: C — It answers a likely objection to the conclusion that more parks should be built

    The sentence concedes that cost is a point against building parks and then replies that the benefit outweighs it, so it answers an objection to the conclusion. The conclusion is the recommendation to build more parks, the evidence about lower crime comes in the opening statement, and the sentence says nothing against that evidence.

  12. A survey of 500 shoppers leaving an expensive department store found that 90 per cent said they would pay more for locally made goods. The store’s manager concludes that most shoppers in the city would pay more for locally made goods. Which of the following, if true, most seriously weakens the manager’s conclusion?

    1. The store was opened ten years ago and has been refurbished twice since then
    2. Every shopper in the survey was asked the question in exactly the same words
    3. Locally made goods are sold in many different shops across the city, and not only in this one department store
    4. Shoppers at this store have much higher incomes, on average, than shoppers in the city as a whole
    Show answer

    Answer: D — Shoppers at this store have much higher incomes, on average, than shoppers in the city as a whole

    The manager generalises from shoppers at an expensive store to all shoppers in the city. If these shoppers are much better off than shoppers generally, their willingness to pay more may not carry over, so the sample is unrepresentative and the conclusion is weakened. The store’s age and refurbishment are irrelevant, asking everyone the same question in the same words, if anything, strengthens the survey, and the wide sale of local goods does not show that the sample is unrepresentative.

  13. A company argues: “Output per employee rose by 8 per cent in the year after we moved to a four-day working week, so the four-day week raises productivity.” Which of the following would be most useful to know in evaluating this argument?

    1. Whether output per employee rose by a similar amount over the same year at comparable firms that kept a five-day week
    2. Whether employees say that they prefer a four-day week to a five-day week
    3. Whether the founder of the company supported the move to a four-day week
    4. Whether the move to a four-day week was announced to the general public in a formal press release issued by the company’s head office
    Show answer

    Answer: A — Whether output per employee rose by a similar amount over the same year at comparable firms that kept a five-day week

    The claim is causal, so the most useful thing to learn is whether the same rise occurred anyway: if comparable firms with a five-day week saw a similar rise, the change was probably not responsible, and if they did not, the claim is strengthened. Preferences, the founder’s view and the form of the announcement do not bear on whether output rose because of the four-day week.

  14. A café owner argues: “Sales rose by 10 per cent in the month after I introduced free Wi-Fi, so the free Wi-Fi increased my sales.” Which of the following findings, if true, would weaken the owner’s argument?

    1. A large office building opened next to the café during that same month
    2. Sales at other cafés on the same street also rose by about 10 per cent that month
    3. Customers who used the Wi-Fi stayed longer and ordered more drinks than other customers did
    4. The owner switched on the free Wi-Fi on the first day of that month
    Show answer

    Answer: A — A large office building opened next to the café during that same month; B — Sales at other cafés on the same street also rose by about 10 per cent that month

    A new office building next door, and a similar rise at other cafés on the street, both offer other explanations for the increase, so each weakens the claim that the Wi-Fi caused it. Wi-Fi users staying longer and ordering more supports a mechanism, so it strengthens the claim, and the date on which the Wi-Fi was switched on is neutral.

  15. A resident argues: “The proposed bypass is a bad idea. Its designer once missed a deadline, so her design cannot be trusted. We must therefore either scrap the bypass or live with permanent traffic jams.” Which of the following flaws does the resident’s reasoning contain?

    1. It rejects the design by pointing to something about the designer rather than to the design itself
    2. It presents only two alternatives when other courses of action may be available
    3. It concludes that one event caused another merely because the first came before the second
    4. It uses its own conclusion, reworded, as one of the premises offered to support it
    Show answer

    Answer: A — It rejects the design by pointing to something about the designer rather than to the design itself; B — It presents only two alternatives when other courses of action may be available

    Pointing to the designer’s missed deadline instead of to anything wrong with the design is an attack on the person, and offering only ‘scrap it or accept permanent jams’ is a false dilemma. The argument claims no causal link from one event to another, and no premise merely restates the conclusion, so the other two flaws are absent.

  16. Read the passage. “Public libraries should remain free to use. They give people who have no internet at home access to information, and charging fees would exclude those who need the service most. Of course, running a library costs money. But that cost is small compared with the benefit to the community.” Which of the following statements serve as reasons supporting the conclusion that public libraries should remain free to use?

    1. Libraries give people who have no internet at home access to information
    2. Charging fees would exclude those who need the service most
    3. Running a library costs money
    4. Public libraries should remain free to use
    Show answer

    Answer: A — Libraries give people who have no internet at home access to information; B — Charging fees would exclude those who need the service most

    The access that libraries give to people who have no internet at home, and the exclusion that fees would cause, are the reasons offered for the conclusion. That running a library costs money is a counter-consideration, introduced by ‘Of course’ and then answered, so it works against the conclusion; and the statement that libraries should remain free is the conclusion itself, not a reason for it.

  17. A hospital manager argues: “The new bus route passes the hospital gate, so more patients will reach their appointments on time. The number of missed appointments will therefore fall.” On which of the following assumptions does the argument depend, in the sense that the conclusion would not be reasonable if it were false?

    1. At least some missed appointments are at present missed because patients cannot easily reach the hospital
    2. At least some patients will make use of the new bus route
    3. The new route is the quickest way of reaching the hospital for every patient
    4. Every missed appointment at present is caused by difficulty in reaching the hospital
    Show answer

    Answer: A — At least some missed appointments are at present missed because patients cannot easily reach the hospital; B — At least some patients will make use of the new bus route

    If no missed appointments were due to difficulty of access, a route that improves access could not reduce them, and if no patient used the route it would change nothing, so both of those assumptions are needed, and each is modest (‘at least some’). The route being quickest for every patient, and every missed appointment being caused by access, are far stronger claims than the argument needs.

  18. Read the information. “Whenever the river level rises above 5 metres, the lower road is closed. Whenever the lower road is closed, all buses use the ridge route. The river is forecast to reach 6 metres tomorrow.” If all of this is accepted, which of the following outcomes must occur tomorrow?

    1. The lower road will be closed
    2. All buses will use the ridge route
    3. Heavy rain will fall upstream
    4. The ridge route will be more crowded than the lower road usually is
    Show answer

    Answer: A — The lower road will be closed; B — All buses will use the ridge route

    A river above 5 metres closes the lower road, so a forecast of 6 metres forces the closure, and the closure in turn sends all buses to the ridge route. The information says nothing about what causes the rise in the river, so heavy rain upstream is not forced, and nothing is said about crowding, so a comparison of crowding is not forced either.