Question

QUESTION 2


Which of the following statements motivate the use of informal proof? Answer true or false to the

following informal proof statements:


a) Truth tables cannot demonstrate logical consequence for formulas containing more than 10

atoms.


b) Informal proof can sometimes explain why a logical consequence holds better than alternative

methods.


c) Not all connectives are truth functional, and hence truth tables do not capture the fully general

case of logical consequence.


d) Informal proofs contain no symbols and so can be understood by everyone.

Answer 1

With an informal proof, we might see compelling evidence that something is so but, at this level, it is possible that an exception exists somewhere.

So, the correct answer is c).