4.5 The value of a second opinion: Consider the context of Exercise 4.1. Now suppose that because you feel that cancer is such a serious disease, you decide to seek a second opinion about your problem. You look for another physician, perhaps an oncologist, who will suggest either that a new independent laboratory test be obtained, or that a new pathologist evaluate the results of the same test. The purpose of either procedure is to see whether a new test or a new reading of the same results will change your opinion about your chance of your having the disease. (Because such tests can be quite invasive, and even dangerous, multiple readings of the same results are often taken rather than additional invasive procedures being performed.) In either case, the result will be either positive again (confirmatory), or perhaps this time it will be negative. Suppose the second test is positive again. How should that affect your belief about your having this cancer?