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Logical Reasoning: The Anatomy of an Argument

Premises, conclusions and the load-bearing gap between them, with an argument taken apart block by block before any question type is named.

9 topics · 35 questions

Each topic is a path, not a menu: work down it in order and every question builds on the one above. Click any of them to watch the answer draw itself.

Premises and Conclusions

  1. How it worksHow do you tell the premise from the conclusion in 'Rain is forecast, so the picnic will be cancelled'?
  2. How it worksWalk me through drawing an argument as support blocks on the bottom and one claim resting on top of them.
  3. Worked exampleWalk me through labeling each part of 'Sea ice is shrinking. Shrinking ice starves polar bears. So bear numbers will fall.'
  4. Common mistakeWhy isn't the last sentence of an argument automatically its conclusion?
Your turneasy1 of 3
Editorial: The city's bus fleet has been in service for 14 years, and maintenance spending has risen in each of the past four budget cycles. Replacing the fleet would cost 32 million dollars up front, but it would cut annual maintenance spending by nearly half. The council should approve the replacement at this month's session. Which one of the following most accurately expresses the conclusion of the editorial's argument?

Finding the Conclusion When It Is Not Last

  1. How it worksHow does the 'therefore' test find the conclusion when no indicator word is anywhere in sight?
  2. Worked exampleFind the conclusion of 'Pesticides should be banned. They kill bees, and bees pollinate a third of our crops.'
  3. Going furtherWhat happens when a stimulus offers two claims and each one looks like it is supporting the other?
  4. Common mistakeWhy isn't the sentence sitting right after 'because' ever the conclusion of an argument?
Your turnmedium1 of 3
Restaurant critic: Diners have complained for years that the Pell Street district offers nothing affordable. That complaint no longer holds. 14 of the district's restaurants now serve a fixed-price lunch under 20 dollars, and three of the four newest openings there are counter-service rooms with no table minimum. Which one of the following most accurately expresses the conclusion of the critic's argument?

Conclusion and Premise Indicators

  1. How it worksHow do 'thus', 'hence' and 'it follows that' point forward to a conclusion while 'because' points backward to a premise?
  2. How it worksWalk me through how 'for' and 'since' flip which half of a sentence is doing the supporting.
  3. Common mistakeWhy doesn't 'so' always mark a conclusion, as in 'She was so tired that she slept through the alarm'?
  4. Worked exampleFind the indicator words in 'Since the bridge is closed, traffic will divert, and thus Main Street will jam.'
  5. Going furtherWhat changes about your read when an argument carries no indicator words at all?
Your turnhard1 of 3
Advertisement: Anyone who has driven the Marek 400 knows the difference. The car returns 51 miles per gallon on the highway, for its engine idles at a lower speed than any competitor's, and it carries 24 cubic feet of cargo besides. Which one of the following best describes the function of the word 'for' in the advertisement?

Subsidiary and Intermediate Conclusions

  1. How it worksHow does an intermediate conclusion sit on a middle floor, held up from below and holding something up from above?
  2. Worked exampleWalk me through the two levels in 'Ads work, since sales rose. So the agency deserves the bonus it was promised.'
  3. Common mistakeWhy isn't the intermediate conclusion the credited answer when a question asks for the main point?
  4. Going furtherWhat happens to the picture when an argument stacks three levels of conclusion instead of two?
Your turnmedium1 of 3
Economist: Household savings in Verland have risen for 9 consecutive quarters. A population that saves more spends less on imported goods, so Verland's trade deficit will narrow this year. A narrowing deficit strengthens the currency, and a stronger currency means the central bank will face pressure to cut rates before the summer. Which one of the following most accurately expresses the main conclusion of the economist's argument?

Background Information That Is Not a Premise

  1. How it worksHow do you test whether a sentence is doing support work or merely setting the scene?
  2. Worked exampleFind the real premise in 'Mercury is closest to the Sun. It has no atmosphere, so it cannot hold heat overnight.'
  3. Common mistakeWhy isn't every factual sentence inside a stimulus a premise for the conclusion?
Your turneasy1 of 3
Marine biologist: Kelp forests grow along rocky coasts where the water stays cool through the year. The forest off Camber Point has thinned by 58 percent since 2004, and sea urchin counts there have tripled over the same period. Urchins graze the holdfasts by which kelp attaches to rock, so the urchin boom is what has thinned the Camber Point forest. Which one of the following plays the role of background rather than support for the biologist's conclusion?

Counterpremises and Concessions

  1. How it worksHow does 'admittedly' or 'although' flag material the arguer is conceding rather than relying on?
  2. Worked exampleWalk me through 'Although the drug has side effects, it cures the disease, so it should be approved' part by part.
  3. Going furtherWhat happens when the conceded material is actually heavier than the premise the arguer keeps?
  4. Common mistakeWhy isn't a concession the same thing as the arguer giving up on the conclusion?
Your turneasy1 of 3
Board member: Admittedly, the proposed warehouse would take 19 acres of land the trust bought for conservation, and 140 residents have written to object. But the site drains badly, has never supported the meadow species the trust hoped for, and would fund three restorations elsewhere. The trust should sell. Which one of the following most accurately describes the role of the first sentence in the board member's argument?

An Argument Versus a Set of Assertions

  1. How it worksHow do you check whether a stimulus argues for anything or just reports a pile of facts?
  2. Common mistakeWhy doesn't a stimulus containing a strong opinion automatically contain an argument?
  3. Going furtherWhat kinds of Logical Reasoning questions attach to a stimulus that has no conclusion at all?
Your turneasy1 of 3
Field report: The wetland at Corry Flats covers 294 hectares. Frog counts there fell by 46 percent between the two most recent surveys. Water samples taken at the inflow show nitrate levels above the regional average. Two new housing developments were completed upstream during the same period. Which one of the following most accurately describes the field report?

The Gap Between Premises and Conclusion

  1. How it worksHow do you spot the gap in 'The new hire types quickly, so she will make a great assistant'?
  2. How it worksWalk me through drawing premise blocks with a visible hole where the conclusion still needs support.
  3. Worked exampleFind the gap in 'Sales rose right after the logo changed, so the logo change caused the rise.'
  4. Ties togetherHow does one gap get attacked by a weaken question and patched by an assumption question?
Your turnmedium1 of 3
Manager: Applicants for the archive post sit a typing test, and this year's leading candidate reached 116 words per minute with an error rate of 3 percent. That is the fastest result the department has recorded. She will be the best archivist we have hired. Which one of the following identifies the gap between the manager's evidence and conclusion?

Reading a Stimulus Once and Knowing Each Sentence's Job

  1. How it worksHow do you hand each sentence a job — background, premise, counterpoint, conclusion — on a single pass?
  2. Worked exampleWalk me through a one-pass read of 'Critics say the tax failed. But revenue rose 8 percent. So the tax worked.'
  3. Going furtherWhat changes about that one-pass read when the stimulus holds two speakers instead of one?
  4. Common mistakeWhy isn't underlining every sentence the same as understanding how they fit together?
Your turneasy1 of 3
Critics say the harbour tax failed. But revenue from the port rose 15 percent in the 6 years after it took effect, and cargo volumes held steady across the same span. The tax worked. Which one of the following correctly assigns a job to each of the four sentences, in order?

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