Question 1.
a) Two negatives make a positive.
b) Barry's attitude is simply too negative.

Conclusion
Therefore Barry's attitude is in fact positive.

Valid     Invalid

Question 2.
All rational arguments concerning the economy and the banking crisis must be considered conscientiously. However some of the arguments one hears from economists are clearly not rational.

Conclusion
Therefore one should appreciate that some of the arguments economists propound must not be considered conscientiously.

Valid     Invalid

Question 3.
a) Both premises in this syllogism are untrue.
b) Words constitute all the content of any premise.

Conclusion
Therefore the words in this syllogism are all false.

Valid     Invalid

Question 4.
a) A photon is not an electron.
b) A neutrino is not a photon.

Conclusion
Therefore a neutrino is not an electron.

Valid     Invalid

Question 5.
a) If God exists then one would expect to see a wonderful and marvellous nature.
b) There is a wonderful and marvellous nature.

Conclusion
Therefore God must exist.

Valid     Invalid

Question 6.
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 stabbing the man shortly before he died.
h) Mary admitted that she had carried out the murder.

Conclusion
Therefore Mary committed the murder.

Valid     Invalid

Question 7.
a) All birds are reptiles.
b) All reptiles are amphibians.
c) All amphibians are invertebrates.
d) All invertebrates are protists.
e) All protists are eukaryotes.
f) All eukaryotes are bacteria.

Conclusion
Therefore all birds are bacteria..

Valid     Invalid

Question 8.
If time travel was possible, one could travel to the past and kill one's own grandmother.
But if one killed their own grandmother then one would not be born.

Conclusion
Therefore time travel is impossible.

Valid     Invalid

Question 9.
a) Triangles have four sides.
b) Squares are triangles.

Conclusion
Therefore squares have four sides.

Valid     Invalid

Question 10.
a) Without procreation there would be no evolution of any creatures.
b) Evolution does occur.

Conclusion
Therefore creatures must be motivated towards procreation.

Valid     Invalid

Question 11.
a) All events in the world are caused by other events that precede them.
b) Dusky evenings always precede dark nights.

Conclusion
Therefore the dusky evenings cause it to be dark at night.

Valid     Invalid

Question 12.
a) Whatever goes up must go down.
b) The train robbers are up before the beak.

Conclusion
Therefore the train robbers will be sure to go down.

Valid     Invalid

Question 13.
a) If George duped Tony then Jack duped his colleagues.
b) If Donald duped the public then George duped Tony.

Conclusion
Therefore if Donald duped the public then Jack duped his colleagues.

Valid     Invalid

Question 14.
a) George Orwell said inside every fat person there is a thin person trying to get out.
b) Billy Bunter was a fat person.

Conclusion
Therefore Billy Bunter was really two people.

Valid     Invalid

Question 15.
a) If murder is wrong, then getting little brother to murder is wrong.
b) Murder is wrong.

Conclusion
Therefore getting little brother to murder is wrong.

Valid     Invalid