Headaches are one effect that can come from inhalation of isopropyl alcohol. Isopropyl alcohol, or rubbing alcohol, is often used in the home or in medical facilities to treat various conditions or to sterilize instruments and skin. However, if isopropyl alcohol is inhaled there can be serious side effects.
1a) Definition of contradiction: A contradiction exists any time a proposition P is asserted to be true in conjunction with its negation, not-P. 1b) Definition of conjunction: A conjunction is a connective that joins two propositions.
In proof by contradiction (also known as reductio ad absurdum, Latin for by reduction to the absurd), it is shown that if some statement were true, a logical contradiction occurs, hence the statement must be false. A famous example of proof by contradiction shows that is an irrational number :