A my K ind development from sense data theorists such as G E Moore and Bertrand Russell at the start of the century, to intentionalists such as G.E.M Anscombe in midcentury, to disjuncitivists such as John McDowell in the latter half of the century Second, we can think of perception as a subconscious process, i.e., as whatever process enables us to perceive the world as we Here philosophers have been greatly influenced by research in psychology and, more broadly, in cognitive science At the beginning of the century, gestalt theorists such as the psychologists Max Wertheimer, Wolfang Köhler, and Kurt Koffka rejected the structuralism and atomism that dominated at the end of the nineteenth century and argued that percepts cannot always be decomposed into more basic sensory parts Rather, we must adopt a more holistic picture Though gestaltism largely fell out of favor by mid-century, it nonetheless exerted an important influence on subsequent philosophical work The second half of the century was marked by the emergence of two different views According to constructivism, perception essentially involves an internal inference, one that supplements the initial sensory stimulation In vision, for example, the retinal image is processed by using hidden assumptions to reach perceptual conclusions about the environment In contrast to constructivism, the ecological views that emerged in the second half of the century focused not on internal procedures but on environmental interactions While the constructivist tends to see perception as a static process, ecological theorists like J J Gibson see perception as dynamic For Gibson, the perceptual act is an active engagement with the world In different ways, both of these views gain support from the developments in artificial intelligence discussed earlier in section 3 of this introduction Constructivism, for example, gains plausibility from the computational theory of mind As Orlandi notes, If we recognize symbols as information-carrying structures, and algorithms as containing assumptions and rules to process the symbols, then viewing the perceptual process as computational pretty much amounts to viewing it the way the constructivist does – as an inference from some informational states to others (this volume, p 116) In contrast, ecological views gain plausibility from more recent developments in connectionism Connectionist networks, which attune to the world by spreading levels of activation, seem to work in the dynamic way predicted by the ecological view and without the internal inference process posited by constructivism While the first four chapters of the volume can be seen as tracing back to problems that were brought to the forefront of philosophical inquiry by Descartes, the topic of the fifth chapter traces back instead to a problem that was brought to the forefront by Locke In this chapter, Jens Johansson takes up the topic of personal identity and, in particular, the question of what it takes for us to persist through time Locke’s answer, proposed in the 17th century, was that someone existing 12