Gilbert Harman

Originally published in 1990. This study argues that scepticism is an intelligible view and that the issue scepticism raises is whether or not certain sceptical hypotheses are as plausible as the ordinary views we accept. It discusses psychological concepts, definitions of knowledge, belief and hypothetic inference. Starting from ‘Is skepticism a problem for epistemology’, the book takes us through the argument for the possibility of scepticism, including looking at sense data and considering memory and perception.

My thesis is that morality arises when a group of people reach an implicit agreement or come to a tacit understanding about their relations with one another. Part of what I mean by this is that moral judgments - or, rather, an important class of them - make sense only in relation to and with reference to one or another such agreement or understanding. This is vague, and I shall try to make it more precise in what follows. But it should be clear that I intend to argue for a version of what has been called moral relativism.

How do people reason about the what follows from certain assumptions? How do they think about implications between statements. According to one theory, people try to use a small number of mental rules of inference to construct an argument for or proof of a relevant conclusion from the assumptions (e.g., Rips 1994). According to a competing theory, people construct one or more mental models of the situation described in the assumptions and try to determine what conclusion fits with the model or models constructed (e.g., Johnson-Laird 1983, 2006). The present collection offers eleven contributions to the mental models theory.