infallible — that is, iffit belongs to at least one relevant type all instances of which are true beliefs. It may at the same time belong to fallible types.
For instance, we may think that one of the relevant types is that ofbelief itself. Each belief is based on the method of believing, but no belief is knowledge in virtue of being based on it. Typically (but not necessarily), the relevant types of belief in virtue of which a given belief is knowledge will be among its narrowest ones.
1.3 Methods infallibilism and the theory of knowledge
We introduce and constrain the notion of methods in two ways. First, through method infallibilism itself, the notion is tied to our intuitions about knowledge and to a notion of possibility (ch.4). Second, we give a formal representation of methods which tells us what structure some-thing must have if it is to correspond to the notion (ch.5). In particular, we introduce structural relations among methods themselves which go beyond what method infallibilism requires. Moreover, the formal repre-sentation allows us to individuate a few specific methods.9
None of this guarantees that there are methods, that is, that there are a range of natural properties of belief that correspond to our notion. What makes a property a natural one is that it enters in simple relations with other properties. So the hope is that the notion of method can be put to use in a variety of contexts beyond method infallibilism. The formal models we put forward are a first step in that direction: they set out a number of systematic relations among methods themselves and explain some important links between belief and knowledge (ch. 5). A second step is our hypothesis that the infallibility of methods is assessed with respect to a space of real possibilities that is independently involved in
9. The structural relations in question are method union and composition (see sec.
5.2.2). The methods we individuate are Pure Reason, Deduction, and Introspection and Confidence methods (see sec.5.5).
1.3. Methods infallibilism and the theory of knowledge 7 our counterfactual reasoning (ch.7). Further steps to vindicate methods
would relate them other notions than knowledge, belief and real possi-bility. They may be linked to action, through pairing epistemic methods with decision-making methods to explain action. They may be related to reasoning through diachronic belief-formation and belief-revision meth-ods. They may be related to norms of belief, if we explain why beliefs ought only to be based on infallible methods. They may be related to value or credit, through an account of why true beliefs based on such methods are distinctively valuable or in some sense creditable to one. I will not explore these questions in the present thesis, but they will have to be investigated in future work.
The exuberant profusion of theories of knowledge sparked by the Get-tier problem has made it clear that one should not put forward an account of knowledge simply on the basis of its ability to yield intuitive judge-ments about a few problematic cases. Accounts of knowledge should also bemotivated; they should make sense of the fact that knowledge is a distinguished property and of the role we expect it to play in thought and action. Call this (admittedly vague) desideratum theCraig desideratum.10 The present work meets it in a minimal way by defending method infalli-bilism not on the basis of a few problematic cases, but rather on the basis of general constraints on the structure of accounts of knowledge in terms of possibility of error. The desideratum would be fully met if we could put method infallibility to use in the explanation of action, the norms of belief, assertion and practical reasoning, or in an explanation of the value of knowledge. This will not be done in the present work, but we hope that the reader familiar with recent epistemology will have a feeling of how these developments can be pursued.
To sum up, even though the notion of method is defined through method infallibilism itself, this does not make methods infallibilism triv-ially true, nor does it make it untestable. Method infallibilism will turn
10. It was notably put forward byCraig(1990, 1-2). MarkKaplan(1985) advanced a similar idea, though in order to argue that knowledge was not an interesting property since it failed to satisfy the desideratum.
out false if there is no range of sufficiently natural properties of beliefs that validates it. Method infallibilism cannot be tested by comparing our intuitions about knowledge with our intuitions about methods (since we have none of the latter), but it is tested by whether the notion of method integrates smoothly with other notions like belief and action.
Now if the project succeeds, this means that there are methods, and that knowledge is belief based on infallible methods. If so, it is open to consider that method infallibilism provides areductive accountof knowl-edge, in the sense that methods and impossibility would be ontologically prior to knowledge. This could be the case even though the theoretical concept of method is ultimately derived from our ordinary concept of knowledge. To use an older terminology: though knowledge is the first thingin the order of discovery, methods may be the first thing in the order of things. I am not going to defend the ontological priority thesis in the present work. But if it was true, it would give a sense in which methods infallibilism is ananalysis of knowledge, as opposed to an analysis of the concept of knowledge.
1.4 Overview
This work is divided into four parts: history, epistemology, formal epistemology and semantics. The first part situates infallibilism in a broader historical perspective. The second part defends method infalli-bilism on epistemological grounds. The third part implements method infallibilism in a new type of model for belief and knowledge. In the fourth part, ordinary knowledge ascriptions are linked to a notion of possibility that transpires from the semantics of modals and subjunctive conditionals. Each part can be read fairly independently, though their present order is the most natural one.
Three appendices (A,B,C) provide supplementary materials for chap-ters3,4and5, respectively. Two further appendices (DandE) are stand-alone treatments of advanced questions on safety-style conditions on knowledge, of which method infallibilism is an instance.
1.4. Overview 9