1.71 Some of the boxes you start with will be empty. Some will already contain a number. The boxes that contain numbers from the start are given. You don't need to engage in any sort of reasoning to know that it's a 3 that goes in the second box from the left in the top row. That box is given to you for free. So are all the other boxes that contain numbers. The only rational basis for adding more numbers to the grid will derive other numbers from the numbers given. If there is no reasoning that is available to you that takes you from the numbers given to some conclusion about what number to put into an empty box, you simply cannot know what goes in there and cannot justifiably judge that some number gets in there. If nothing is given to you for free, you simply could not have any justified beliefs about what number would go where.
1.72 The foundationalist thinks that something similar is true when it comes to the justification of any belief. Without non‐inferentially justified beliefs (i.e. givens, or freebies, if you like), you couldn't rely on reasoning to provide you with any justified beliefs. The rational support for any justified belief has to trace back to the support provided to a non‐inferentially justified belief. (In the limiting case, that belief will itself be one of the non‐inferentially justified beliefs.) Happily, the foundationalist says, we do have some non‐inferentially justified beliefs. They are justified even if we cannot find support for them in other justified beliefs we have, and they are the foundation that accounts for all the derivatively justified beliefs we form by reasoning well from these starting points.
1.6 Objections to Foundationalism
1.73 It might be useful to think about how far we can push this analogy, because it will help us see why many philosophers have been critical of foundationalism, and help us see how foundationalists should respond to this criticism in fleshing out their view.
1.74 Thus far, foundationalism – as we've stated it – is a purely structural proposal. It says that (i) every chain of justified beliefs must include at least some non‐inferentially justified belief and (ii) every inferentially justified belief must derive its justification from non‐inferentially justified beliefs. If this view is correct, nothing gets into Your Book of Justified Beliefs unless it derives its justification from another justified belief via inference or is non‐inferentially justified and derives its justification from something other than another belief. We haven't yet said anything substantive about the nature of these non‐inferentially justified beliefs, because we haven't said what these beliefs are about, what supports them, or how what supports them ensures that they have the right properties to be justified.
1.75 While the sudoku analogy can help us understand the sort of structure that the foundationalist thinks has to be in place in order to have justified beliefs, it does highlight one of the features that some critics of foundationalism find objectionable. In sudoku, the given entries that serve as the foundation for all subsequent thinking about the puzzle are beyond rational scrutiny and cannot be revised. (The given entries are simply there, in sudoku, and it's built into the game that there's no room to doubt them.) Does the foundationalist really think that the foundation for all our thinking about the world rests on foundations that we have no room to doubt? Thinking that such beliefs are in short supply, critics of at least one version of strong foundationalism could argue as follows:
Argument from Defeasibility
P1. If there are non‐inferentially justified beliefs that are like the numbers given at the start of the puzzle, then you cannot form correct beliefs about the world by reasoning well from your justified beliefs in such a way that you're led to suspend judgment about whether one of these properly basic beliefs is true, and you cannot form the correct beliefs about the world by reasoning from your justified beliefs to the conclusion that one of these beliefs is false.
P2. However, none of our beliefs are immune to this sort of process of rational revision.
C. Thus, it isn't true that there are non‐inferentially justified beliefs that are like the numbers given at the start of the puzzle.
1.76 To understand the Argument from Defeasibility, we need to understand what it means to say that justification is defeasible. In short, “defeasible” literally means “able to be defeated,” or diminished. The kind of thing that can potentially defeat the justification you have for believing something is new information you might acquire. More specifically, this happens when the rational force of whatever evidence served to justify you holding a belief is undermined and overridden by you learning new relevant information.36 The terms “undermining defeater” and “overriding defeater” are used to pick out two different ways that you can “lose” the justification you have for believing something.
1.77 To understand the difference between undermining and overriding defeat, think about promises. If you promise to meet a friend, that's a good reason to meet them. If you have no reason to do anything else, that reason might be decisive in that it might determine what you should do, all things considered. If, however, you make a promise to meet a friend and you then encounter a child who needs your help, the reason you have to meet a friend could be overridden by a weightier reason, to render aid. Alternatively, if your friend calls the meeting off, the reason you had could lose its rational force because the ground of the reason has been cut away. In this case, the reason is undermined.37
1.78 Something similar happens with belief. The testimony of a friend might give you a good reason to believe that, say, they plan on staying around to have coffee with you. Seeing them slipping out a back entrance to the parking lot might override that, as it's strong evidence that they're sneaking away for some reason. In cases of overriding defeat, the justification provided by evidence for p is defeated or lost because you acquire strong evidence for ~p. In tasting the orange juice, you might judge that there's something wrong with it because of a funny taste. You remember that you've just brushed your teeth and remember that the minty toothpaste affects how things taste to you. Here, the justification provided by your evidence is undermined. The funny taste is typically some reason to think that there's something wrong with the juice, but there's some additional evidence in the form of your knowledge that you've just brushed your teeth that you need to take account of. The combined evidence doesn't support the hypothesis that there's something wrong with the juice, not even if a part of that evidence (i.e. the way it tastes) could have supported that hypothesis that there's something wrong with the juice if only you didn't have the additional evidence that brushing your teeth affects the way things taste to you.
1.79
