Inferring and Explaining

10 InferrIng and exPlaInIng So what to do? He continues with his con- struction metaphor: I realized that it was necessary, once in my life, to demolish everything completely and start again right from the foundations if I wanted to establish anything in the sciences that was stable and likely to last. 3 Epistemological demolition just for the sake of demolition is a pretty silly project. But Des- cartes is interested in demolition, like much of contemporary urban renewal, for the sake of new construction. He wants new founda- tions that will allow him more confdence in his philosophical and scientifc thinking. He’s immediately confronted with two serious prob- lems. What is going to be an efcient method for his demolition (a wrecking ball, bulldozers, or dynamite?)—he has an awful lot of beliefs, afer all—and what is going to be his standard for stability once he has cleared the ground and begins his new construction? He answers these questions with a radical proposal. Reason now leads me to think that I should hold back my assent from opinions that are not completely cer- tain and indubitable just as carefully as I do from those that are patently false. So, for the purpose of rejecting all my opinions, it will be enough if I fnd in each of them some reason for doubt. And to do this I will not need to run through them all indi- vidually, which would be an endless task. Once the foundations of a building are undermined, anything built on them collapses of its own accord; so I will go straight for the basic principles on which all my former beliefs rested. 4 Confdence-Undermining Possibilities Your car is in the shop, but a friend has gra- ciously loaned you her pickup. As you are driving along a long desolate stretch of rural highway, you suddenly think about gas. Fortu- nately, when you look down at the gauge you see that you have almost three-quarters of a tank. You continue your drive peacefully contemplat- ing your planned trip over Christmas break. Te next morning your friend calls you with some unsettling news: “I forgot to tell you yesterday when you picked up the truck that the gas gauge is all screwed up. It always reads three-quarters of a tank.” Two things follow pretty directly from this little story. Your reassurance last night on the highway was ill-founded. It may have been psy- chologically comforting to read the gauge as saying that you had plenty of gas, but you now know that there was no good reason for your confdence. It was merely good luck that you had enough fuel to get home. In addition, read- ing the gauge in the future will never produce the kind of conviction you felt last night—nor should it. Tere are people with a certain kind of intel- lectual temperament who are called skeptics. A skeptic might have the feeting worry about having enough gas, look at the gauge, and feel relieved but then start to wonder: “How do I know this gauge works properly?” Even with- out the friend’s call the next morning, the skep- tic can work herself into a state of doubt where reading the gauge does not produce the desired intellectual confdence.