An Introduction to Critical Thinking and Creativity - always yours

246 SOLUTIONS TO EXERCISES
13.4 One explanation is that the man was just lucky, but this is not too likely. The simpler
and more plausible explanation is that the man has got all 20 numbers written down in
various places on him, and depending on what his audience comes up with, he reveals the
appropriate number, for example, on his left foot, on a piece of paper in his right pocket,
or on his left wrist. To test whether this is the case, we can search him beforehand or ask
him to guess the number from a much larger range or have him write down beforehand the
number he is going to implant in the audience's mind.
13.5.a It is indeed wrong to criticize a theory on the grounds that there is no proof that it
is correct, if by that we mean the theory lacks conclusive evidence that entails the theory.
But it would still be rational to accept a theory if it had plenty of evidence indicating that it
was highly likely to be true. This is why it is also wrong to say that scientific theories that
have not been proven true are accepted solely on the basis of faith, because these can be
theories that have plenty of supporting evidence and can offer useful predictions.
13.5.b A theory does not fail to be scientific just because it does not offer 100% accurate
predictions. It could be that the theory is fine, but it is difficult to get precise data to make
predictions in conjunction with the theory. A scientific theory can also make statistical and
probabilistic predictions without being able to predict every single event accurately.
13.5.C It is wrong to think of science and logic as completely distinct. Science also relies
on logic including deduction. Scientists need logic to discover the implications of their
theories, generate predictions, and check for inconsistencies, among other things.
SOLUTIONS FOR CHAPTER 14
14.1.a The method of concomitant variations.
14.1.b The method of difference.
14.1.C The joint method.
14.1.d The method of difference.
14.2 Situation 1.
14.3.a None can be applied, since there is no single cause common to all situations in
which E occurred. It could be that E has multiple or complex causes, or its cause is not
among the list here.
14.3.b B, according to the joint method.
14.3.C C, according to the joint method.
14.3.d D.
14.3.e C.
14.4.a True. Given the more general joint method, there is no need for the method of agreement
or the method of difference.
14.4.b True.