Think Logically ! No. 1

Question 1.
a) All ducks quack.
b) Donald is a duck.

Conclusion
Therefore: Donald quacks.

Valid Invalid

Question 2.
a) All female logicians are clear thinkers.
b) All lawyers are clear thinkers.

Conclusion
Therefore all female logicians are lawyers.

Valid Invalid

Question 3.
a) Men think only about sex.
b) A man called Gary is thinking.

Conclusion
Therefore Gary is thinking about sex.

Valid Invalid

Question 4.
a) Where there is poverty there is crime.
b) There is poverty in Camberwell.

Conclusion
Therefore there is crime in Camberwell.

Valid Invalid

Question 5.
a) Where there is poverty there is crime.
b) There is crime in Camberwell.

Conclusion
Therefore there must be poverty in Camberwell.

Valid Invalid

Question 6.

a) Some mammals are marsupials.
b) All kangaroos are mammals.

Conclusion
Therefore all kangaroos are marsupials.

Valid Invalid

Question 7.
a) All ducks bark.
b) Donald is a duck.

Conclusion
Therefore Donald barks.

Valid Invalid

Question 8.
a) When I get hungry I could eat a horse.
b) I am hungry now.

Conclusion
Therefore I should eat a horse.

Valid Invalid

Question 9.
a) Blue and yellow make green.
b) Blue and red make brown.

Conclusion
Therefore blue and white make sky blue.

Valid Invalid

Question 10.
a) Jenny lives in Paris.
b) Paris is in New Zealand.

Conclusion
Therefore Jenny lives in New Zealand.

Valid Invalid

Question 11.
a) Men are from Mars.
b) Women are from Venus.

Conclusion
Therefore men and women will never understand each other.

Valid Invalid

Question 12.
a) The man was stabbed to death.
b) Mary was seen leaving the scene of the crime shortly after the time of the murder.
c) Blood found on Mary's trousers was the same as the victim's.
d) Only Mary's fingerprints were found on the murder weapon.
e) No other people were witnessed near the scene of the crime.
f) Mary's DNA was found on the victim's body.
g) The CCTV evidence showed only Mary entering and leaving the victim's flat.

Conclusion
Therefore Mary committed the murder.

Valid Invalid

Question 13.
a) Only language users employ generalisations.
b) Not a single animal uses language.
c) At least some animals reason.

Conclusion
Therefore reasoning beings employ generalisations.

Valid Invalid

Question 14.
The results from a logic test taken by 500 women and 500 men showed that:
a) Some women are more logical than some men.
b) Some men are more logical than some women.
c) The top ten performers were all women.
d) The bottom ten performers were all men.

Conclusion
Therefore the results prove that overall women in the test were better than the men at the logic.

Valid Invalid

Question 15.
a) Water is a molecule composed of two hydrogen atoms and one oxygen atom.
b) Every observation or examination by microscope has confirmed this.

Conclusion
Therefore we can predict that every future examination of water will reveal the same chemical composition.

Valid Invalid