Criticizes non-evidentialist theories of knowledge as they bear on external world skeptical arguments. The theories are held to provide no good way to understand the intuitive appeal of the arguments for skepticism. An evidentialist characterization is offered of the justification that is needed for knowledge. On the basis of this characterization, an account is given of the appeal of the skeptical arguments. The characterization also provides a basis to object to the arguments.
Keywords: brains in vats, causal theory, closure, criminal standard of justification, justification, knowledge, possibility of error, reliabilism, skepticism, truth tracking