Hilary Putnam deals in this book with some of the most fundamental persistent problems in philosophy: the nature of truth, knowledge and rationality. His aim is to break down the fixed categories of thought which have always appeared to define and constrain the permissible solutions to these problems.

Computation is central to the foundations of modern cognitive science, but its role is controversial. Questions about computation abound: What is it for a physical system to implement a computation? Is computation sufficient for thought? What is the role of computation in a theory of cognition? What is the relation between different sorts of computational theory, such as connectionism and symbolic computation? In this paper I develop a systematic framework that addresses all of these questions. Justifying the role of computation (...) requires analysis of implementation, the nexus between abstract computations and concrete physical systems. I give such an analysis, based on the idea that a system implements a computation if the causal structure of the system mirrors the formal structure of the computation. This account can be used to justify the central commitments of artificial intelligence and computational cognitive science: the thesis of computational sufficiency, which holds that the right kind of computational structure suffices for the possession of a mind, and the thesis of computational explanation, which holds that computation provides a general framework for the explanation of cognitive processes. The theses are consequences of the facts that (a) computation can specify general patterns of causal organization, and (b) mentality is an organizational invariant, rooted in such patterns. Along the way I answer various challenges to the computationalist position, such as those put forward by Searle. I close by advocating a kind of minimal computationalism, compatible with a very wide variety of empirical approaches to the mind. This allows computation to serve as a true foundation for cognitive science. (shrink)

I argue that at least one of the following propositions is true: the human species is very likely to become extinct before reaching a ’posthuman’ stage; any posthuman civilization is extremely unlikely to run a significant number of simulations of its evolutionary history ; we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we shall one day become posthumans who run ancestor-simulations is false, unless we are currently living (...) in a simulation. I discuss some consequences of this result. (shrink)

NOW IN PAPERBACK"€"Starting from a collection of simple computer experiments"€"illustrated in the book by striking computer graphics"€"Stephen Wolfram shows how their unexpected results force a whole new way of looking at the operation of our universe.

We could have been characters in a huge computer simulation. It is a familiar idea that the whole world might be simulated on a computer, and things would seem exactly the same to us (and indeed, who is to say that we are not).

This paper is written from the perspective of a computer scientist and addressed to theoretical physicists. As a consequence it may seem somewhat unusual, but rest assured, everything is really quite simple! The point of this paper is that the study of certain phenomena from computer science suggests that there are computer systems (cellular automata) that may be appropriate as models for microscopic physical phenomena. Cellular automata are now being used to model varied physical phenomena normally modelled by wave equations, (...) fluid dynamics, Ising models, etc. We hypothesize that there will be found a single cellular automaton rule that models all of microscopic physics; and models it exactly. We call this field DM, for digital mechanics. (shrink)

There is something it is like to see a bright red cardinal, to touch a stucco wall, or to hear an ambulance pass by. Each of these experiences has a distinctive phenomenal character. But in virtue of what it is like to have a particular experience---in virtue of the experience's phenomenal character---the world is presented to the subject as being a certain way. ;The dissertation is concerned with the nature of this "phenomenal content". In Chapter One I argue that there (...) is such a thing as phenomenal content, understood as intentional content that supervenes necessarily on phenomenal character. The rest of the dissertation is concerned with the nature of this phenomenal content, and in particular the phenomenal content of visual experiences. In Chapter Two I present and critique the dominant view about phenomenal color content, what I call "standard Russellianism". According to standard Russellianism, the content of color experience consists solely in the representation of specific mind-independent physical color properties. I present an argument against such views based on the possibility of spectrum inversion without illusion. Further, I argue that such views fail to properly accommodate the phenomenon of color constancy. In Chapter Three, I address a different form of Russellian theory of phenomenal content advocated by Sydney Shoemaker. ;I present my own positive view of phenomenal color content in Chapter Four. There I argue that color content is a kind of Fregean content, involving modes of presentation of colors. In particular, I argue that phenomenal color content involves indexical, response-dependent, and holistic modes of presentation. Finally, in Chapter Five I turn to the spatial aspects of visual experience. I argue against Russellianism for spatial phenomenal content, based on the consideration of a kind of spatial Twin Earth thought experiment. In its place, I argue that spatial phenomenal content is also a kind of Fregean content. (shrink)