Mind, Body, World- Foundations of Cognitive Science, 2013a

strongly influenced by philosophical positions which arose as reactions against
Descartes, such as Martin Heidegger’s Being and Time (Heidegger, 1962), originally
published in 1927. Heidegger criticized Descartes for adopting many of the terms
of older philosophies but failing to recognize a critical element, their interactive
relationship to the world: “The ancient way of interpreting the Being of entities is
oriented towards the ‘world’ or ‘Nature’ in the widest sense” (Heidegger, 1962, p. 47).
Heidegger argued instead for Being-in-the-world as a primary mode of existence.
Being-in-the-world is not just being spatially located in an environment, but is a
mode of existence in which an agent is actively engaged with entities in the world.
Dawson, Dupuis, and Wilson (2010) used a passive dynamic walker to illustrate
this inseparability of agent and environment. A passive dynamic walker
is an agent that walks without requiring active control: its walking gait is completely
due to gravity and inertia (McGeer, 1990). Their simplicity and low energy
requirements have made them very important models for the development of
walking robots (Alexander, 2005; Collins et al., 2005; Kurz et al., 2008; Ohta,
Yamakita, & Furuta, 2001; Safa, Saadat, & Naraghi, 2007; Wisse, Schwab, & van
der Helm, 2004). Dawson, Dupuis, and Wilson constructed a version of McGeer’s
(1990) original walker from LEGO. The walker itself was essentially a straight-legged
hinge that would walk down an inclined ramp. However, the ramp had to be of
a particular slope and had to have properly spaced platforms with gaps in between
to permit the agent’s legs to swing. Thus the LEGO hinge that Dawson, Dupuis,
and Wilson (2010) built had the disposition to walk, but it required a specialized
environment to have this disposition realized. The LEGO passive dynamic walker
is only a walker when it interacts with the special properties of its ramp. Passive
dynamic walking is not a characteristic of a device, but is instead a characteristic of
a device being in a particular world.
Being-in-the-world is related to the concept of affordances developed by psychologist
James J. Gibson (Gibson, 1979). In general terms, the affordances of an
object are the possibilities for action that a particular object permits a particular
agent. “The affordances of the environment are what it offers the animal, what it provides
or furnishes, either for good or ill” (p. 127). Again, affordances emerge from an
integral relationship between an object’s properties and an agent’s abilities to act.
Note that the four properties listed—horizontal, flat, extended, and rigid—would be
physical properties of a surface if they were measured with the scales and standard
units used in physics. As an affordance of support for a species of animal, however,
they have to be measured relative to the animal. They are unique for that animal.
They are not just abstract physical properties. (p. 127)
Given that affordances are defined in terms of an organism’s potential actions, it
is not surprising that action is central to Gibson’s (1966, 1979) ecological approach
220 Chapter 5