Chapter 8: Applying the Definitions
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Chapter 8 Applying the Deﬁnitions Throughout history, people have studied pure science from a desire to understand the universe rather than practical applications for commercial gain. But their discoveries later turned out to have great practical beneﬁts. Stephen Hawking In Chapter 1, I said that my goal was to get deﬁnitions of notions like causality, responsibility, and blame that matched our natural language usage of these words and were also useful. Now that we are rapidly approaching the end of the book, it seems reasonable to ask where we stand in this project. First some good news: I hope that I have convinced most of you that the basic approach of using structural equations and deﬁning causality in terms of counterfactuals can deal with many examples, especially once we bring normality into the picture. Moreover, the framework also allows us to deﬁne natural notions of responsibility, blame, and explanation. These notions do seem to capture many of the intuitions that people have in a natural way. Next, some not-so-good news: One thing that has become clear to me in the course of writing this book is that things haven’t stabilized as much as I had hoped they would. Just in the process of writing the book, I developed a new deﬁnition of causality (the modiﬁed HP deﬁnition) and a new approach to dealing with normality (discussed in Section 3.5), and modiﬁed the deﬁnitions of responsibility, blame, and explanation (see the notes at the end of Chapters 6 and 7). Although I think that the latest deﬁnitions hold up quite well, particularly the modiﬁed HP deﬁnition combined with the alternative notion of normality, given that the modiﬁed HP deﬁnition is my third attempt at deﬁning causality, and that other researchers continue to introduce new deﬁnitions, I certainly cannot be too conﬁdent that this is really the last word. Indeed, as I have indicated at various points in the book, there are some subtleties that the current deﬁnition does not seem to be capturing quite so well. To my mind, what is most needed is a good deﬁnition of agent-relative normality, which takes into account the issues discussed in Example 6.3.4 (where A and B can ﬂip switches to determine whether C is shocked) and meshes well with the deﬁnition of causality, but doubtless others will have different concerns. 203 204 Chapter 8. Applying the Deﬁnitions Moreover, when we try to verify experimentally the extent to which the deﬁnitions that we give actually measure how people ascribe causality and responsibility, the data become messy. Although the considerations discussed in Chapter 6 (pivotality, normality, and blame assignments ) seem to do quite a good job of predicting how people will ascribe causal responsibility at a qualitative level, because all these factors (and perhaps others) affect people’s causality and responsibility judgments, it seems that it will be hard to design a clean theory that completely characterizes exactly how people acribe causality, responsibility, and blame at a more quantitative level. So where does this leave us? I do not believe that there is one “true” deﬁnition of causality. We use the word in many different, but related, ways. It is unreasonable to expect one deﬁnition to capture them all. Moreover, there are a number of closely related notions—causality, blame, responsibility, intention—that clearly are often confounded. Although we can try to disentangle them at a theoretical level, people clearly do not always do so. That said, I believe that it is important and useful to have precise formal deﬁnitions. To take an obvious example, legal judgments depend on causal judgments. A jury will award a large settlement to a patient if it believes that the patient’s doctor was responsible for an inappropriate outcome. Although we might disagree on whether and the extent to which the doctor was responsible, the disagreement should be due to the relevant facts in the case, not a disagreement about what causality and responsibility mean. Even if people confound notions like causality and responsibility, it is useful to get deﬁnitions that distinguish them (and perhaps other notions as well), so we can be clear about what we are discussing. Although the deﬁnition(s) may not be able to handle all the subtleties, that is not necessary for them to be useful. I have discussed...