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Professional · Civil Service Exam

Logic, assumptions and conclusions

These items ask what follows necessarily from what you are given - or what a statement takes for granted without saying.

For a syllogism, take the statements as true even when they are absurd. The question is whether the conclusion follows, not whether it is factually right, and importing what you know about the world is the fastest way to get one wrong.

For an assumption item, test each option by denying it. If the statement still stands with the option false, it was not assumed. The trap on offer is almost always an option that simply repeats something the statement already said: true, and therefore not an assumption.

Conditional statements reverse badly. `If it rains, the game is cancelled` tells you nothing about what happens when it does not rain.

Worked examples

Try these, then read why.

Written for this platform and generated from the same bank the practice sets draw on. Every wrong option is explained, because knowing why a distractor was tempting is most of the learning.

Assume both statements are true. Which conclusion follows?

Some auditors are inspectors.
All inspectors are bonded officers.
  1. AAll bonded officers are auditors.
  2. BSome auditors are bonded officers. (correct)
  3. CAll auditors are bonded officers.
  4. DSome auditors are not bonded officers.

At least one of the auditors is an inspector, and everyone who is an inspector is a bonded officer, so at least some auditors are bonded officers. Follow the shared term through both statements, and claim no more than they allow. A conclusion that reverses the terms, or upgrades some to all, does not follow.

  • A This swaps the two terms. The premises support a claim about the first group, not about the second.
  • C The premises do not license a claim about every member of the group.
  • D Nothing in the premises establishes an exception.

Statement: To shorten the queue at the records counter, the office will accept requests through the online appointment page beginning next month.

Which one of the following is assumed in the statement above?
  1. AOnline appointments are cheaper for the office than walk-in requests.
  2. BSome of the people who queue at the records counter are able to use the online appointment page. (correct)
  3. CThe records counter will eventually close.
  4. DThe office will begin accepting online appointments next month.

Test each option by denying it: if the statement still stands, the option was not assumed. Deny the key here and the statement falls apart - if nobody who queues could use the page, moving requests online would leave the queue exactly as it is. The commonest trap is an option that simply repeats the statement. Anything already said is not an assumption, however true it is.

  • A The stated aim is a shorter queue, not a smaller cost.
  • C Shortening a queue is not closing a counter, and nothing in the statement points that far.
  • D This is stated outright, not assumed. An assumption is something the statement leaves unsaid.

Assume both statements are true. What follows?

If the payment clears, then the certificate is released.
The certificate is not released.
  1. AThe payment clears.
  2. BThe certificate is released.
  3. CThe certificate is not released.
  4. DThe payment does not clear. (correct)

The rule says that whenever the payment clears, the certificate is released. The second statement tells you the result did not happen, so the condition cannot have held either. A conditional runs one way only. Knowing the result happened tells you nothing, and ruling out the condition tells you nothing.

  • A Working backwards from the result is not valid: the result can have other causes.
  • B This restates the rule's result without the fact that would license it.
  • C Ruling out the condition does not rule out the result.

Practise this properly.

Three examples show you the format. Finding out whether logic, assumptions and conclusions is actually costing you marks takes a measured set, which is what the free diagnostic is for.

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