Watson Glaser Deduction
Does this conclusion follow necessarily from the statements, and nothing but the statements? Your ability to reason strictly from given statements: to see what must be true, and to resist concluding what is merely possible, likely or familiar.
Deduction · Example
All the pilots in the flying club are over 25. Some of the club's members are pilots. Some pilots are women. Therefore,
Proposed statement
Some members of the flying club are over 25.
Practice tests
Every practice set has 10 questions. Pick one to start.
Every answer option, explained
What you'll actually see
Two to four statements (premises) that you must treat as true without exception, ending with 'Therefore,'. 3 to 5 proposed conclusions per set of statements. The real test uses exactly these two options: 'Conclusion follows' and 'Conclusion does not follow'. The instructions tell you to treat the statements as true without exception and to explain that 'some' means at least a portion and perhaps all. Our practice items follow the same format.
Conclusion follows
The conclusion cannot be false if the statements are true. You could prove it step by step using only the statements.
Statements: 'All cats are animals. Tom is a cat.' Conclusion: 'Tom is an animal.' Follows.
Conclusion does not follow
The conclusion could be false while the statements are true. This includes conclusions that are probably true, conclusions that contradict the statements and conclusions that the statements leave open.
Statements: 'All cats are animals. Tom is an animal.' Conclusion: 'Tom is a cat.' Does not follow, because Tom could be a dog.
Worked example
All the pilots in the flying club are over 25. Some of the club's members are pilots. Some pilots are women. Therefore,
Statement 1
Some members of the flying club are over 25.
At least one club member is a pilot, and every pilot in the club is over 25. So at least one member is over 25.
Conclusion follows
Statement 2
All members of the flying club are over 25.
Only the pilots in the club are said to be over 25. Members who are not pilots could be younger. 'Some' members are pilots, not all of them.
Conclusion does not follow
Statement 3
Some women are over 25.
The women pilots might not belong to the flying club. Only the club's pilots are said to be over 25, so nothing about the age of the women is certain.
Conclusion does not follow
Statement 4
No club member under 25 is a pilot.
Every pilot in the club is over 25. So a club member who is under 25 cannot be a pilot.
Conclusion follows
Know what is being assessed
How Deduction works
Each exercise consists of several statements followed by some suggested conclusions. Treat the statements as true without exception, even when they clash with what you know about the world.
Read each conclusion in turn. If it must be true whenever the statements are true, choose 'Conclusion follows'. If it is not a necessary result of the statements, choose 'Conclusion does not follow', even if you believe it to be true.
The word 'some' means at least one, and possibly all. 'Some students are tired' means that at least one student is tired, and perhaps every student is.
Stick to the statements only. Do not let your own knowledge, experience or opinions affect your judgement.
In the full test you have about one minute per question. Most deduction items take 20 to 40 seconds if you draw a quick sketch. Don't spend time on conclusions that you cannot test. If the statements do not settle it, the answer is 'does not follow'.
Where candidates lose points
- Reversing 'all'. 'All A are B' tells you about A, not about B. Do not swap the groups around.
- Treating 'some' as 'most' or 'all'. 'Some' tells you that there is at least one, nothing more. It does not mean most, and it does not mean 'not all'.
- Joining two 'some' statements. The 'some' in each statement may refer to different members. Without a link, no conclusion can be drawn about them together.
- Working backwards from an 'if'. If the result is true, you cannot conclude that it was caused by the condition. Other conditions may also lead to the same result.
- Using real-world knowledge. The statements are the whole world for this test. Facts you know that are not in the statements are not allowed to settle the answer.
- Mixing up 'must' and 'did'. A rule that says what must happen does not tell you what actually happened.
A smarter approach
- 01
Read the statements and translate each one into a simple picture, such as circles for groups or a line of names in order. Treat them all as true.
- 02
Read the conclusion and ask: must this be true? Not 'could it be true' and not 'is it probably true'.
- 03
Test it by trying to make the conclusion false while keeping every statement true. If you can, it does not follow.
- 04
If you cannot make it false without breaking a statement, it follows.
- 05
Check the small words: 'some', 'all', 'no', 'only', 'if', 'before' and 'more than'. They decide the answer.
Tips for Deduction
The test is 'can I make the conclusion false while the statements stay true?'
The test is 'can I make the conclusion false while the statements stay true?'. If yes, it does not follow. If no, it follows.
'Some' means at least one and possibly all
'Some' means at least one and possibly all. From 'some A are B' you can never conclude 'some A are not B' or 'all A are B'.
'All A are B' does not mean 'all B are A'
'All A are B' does not mean 'all B are A'. Do not reverse the statement. From 'all dogs are animals' you cannot conclude 'all animals are dogs'.
'No A is B' can be reversed: it means 'no B is A'.
'No A is B' can be reversed: it means 'no B is A'.
Two 'some' statements do not link up
Two 'some' statements do not link up. 'Some A are B' and 'some B are C' tell you nothing certain about A and C.
'If A then B' lets you conclude B when A is true, and 'not A' when B is false
'If A then B' lets you conclude B when A is true, and 'not A' when B is false. It does not let you conclude A from B, and it does not tell you what happens when A is false.
'Only if' gives a necessary condition
'Only if' gives a necessary condition. 'The team wins only if the striker is fit' means that no fit striker, no win; it does not mean that a fit striker guarantees a win.
Draw it
Draw it. Circles for groups, arrows for rules, a line for rankings. Sketching is faster than doing it in your head and avoids mistakes.
Set aside what you know
Set aside what you know. A conclusion can be true in real life and still not follow. A conclusion can also look silly and still follow.
A conclusion that contradicts the statements is, of course, 'does not follow'
A conclusion that contradicts the statements is, of course, 'does not follow'. Spotting this quickly saves time.
Make the format familiar before test day.
Start with a free set, then build up to full-length mock tests.