Inferring and Explaining

55 Tree very important things follow from all this. Te frst is that evidence evaluation is always relative to what we presently know. If we learn new things and assemble them in new arguments, there will be times when our origi- nal conclusionwill be strengthened, times when it will be weakened, and times when it will be pretty much lef untouched. Te second is that new data are always possible. Te fact that we could imagine rival explanations means that we can imagine new evidence for these rivals. But this last fact leads to our third moral. Just because new data are possible, it does not mean that our assessment of the current evidence is unreliable. If all the rivals are farfetched, then the chances of fnding new data that supports them are pretty slim. We do, of course, need a certain kind of intellectual modesty. We concede that things could change on the basis of new dis- coveries. But at the same time, for some kinds of evidence, we can be pretty confdent that they won’t change . new data and exPerImentatIon exerCIses 1. According to the “pretty picture of science,” why is it possible to disconfrm a scientifc theory but never confrm one? 2. What kind of new data would strengthen Connie’s evidence about what happened at the record hop? What kind of new data would weaken her theory? QuIz sIx For the past few years, I have been forming an uncharitable hypothesis about one of my col- leagues. He is Professor Hide-Smith-Jones, who teaches in the Department of Hermeneutic Metaphysics. I believe that he virtually gives away grades and demands almost no work from his students. His courses are wildly popular with students and have very high enrollments. What started my suspicions was a number of students who complained about the workload in my courses, who I later discovered were all hermeneutic metaphysics majors. A couple of my online students explicitly compared my course to Hide-Smith-Jones’s courses, accusing me of being unfair and unreasonable. This past weekend, I went into the university’s database and looked at the transcripts for all my advisees in the past fve years. Many of them had taken at least one course with Hide-Smith-Jones. I discovered that on average, the grades they earned in his courses were .78 grade points higher than their total grade point averages. 1. Use the tools of inference to the best explanation to assess the quality evidence we have for Johnson’s theory that Hide-Smith-Jones is an easy grader who doesn’t demand much from his students. 2. Explain a test or experiment that could be conducted to test Johnson’s hypothesis. 3. Using inference to the best explanation, show how new data could be discovered that would either help (confrm) or hurt (disconfrm) Johnson’s theory.