PH10A: Introduction to Logic
Additional Categorical Propositions (Addendum to Worksheet 3)
Please prepare for tutorial for the week of March 6, 2006.
Test for the validity of the following arguments using Venn diagrams.
a)
All heroes act based on altruism. No persons who act based on altruism are selfrighteous. So no heroes are self righteous.
b)
Since no invalid argument proves its conclusion and some arguments for God’s
existence are invalid arguments, some arguments for God’s existence prove their
conclusion.
c)
No court that suppresses evidence is impartial. Some courts subject to political
pressure suppress evidence. Therefore some courts subject to political pressure
are impartial.
d)
Anyone who has just lost a lost of blood is likely to faint. No one who is likely to
faint is a safe aircraft pilot. Therefore no one who has lost a lot of blood is a safe
aircraft pilot.
e)
All segregation laws degrade human personality. All laws that degrade human
personality are unjust. It follows then that all segregation laws are unjust.