Can Cognition Be Factorised into Internal and External Components?

0. Platitudinously, cognitive science is the science of cognition. Cognition is usually defined as something like the process of acquiring, retaining and applying knowledge. To a first approximation, therefore, cognitive science is the science of knowing. Knowing is a relation between the knower and the known. Typically, although not always, what is known involves the environment external to the knower. Thus knowing typically involves a relation between the agent and the external environment. It is not internal to the agent, for the internal may be the same whether or not it is related to the external in a way that constitutes knowing. Cognition enables agents to achieve their goals by adjusting their actions appropriately to the environment. Such adjustment requires what is internal to the agent to be in some sense in line with what is external; that matching depends on both internal and external sides. Thus if cognitive science were restricted to what is internal to the agent, it would lose sight of its primary object of study. Although cognition depends on both the internal and the external, one can try to analyse it into internal and external factors. Call a state S narrow if and only if whether an agent is in S at a time t depends only on the total internal qualitative state of S at t, so that if one agent in one possible situation is internally an exact duplicate of another agent 2 in another possible situation, then the first agent is in S in the first situation if and only if the second agent is in S in the second situation. 1 Call S broad if and only if it is not narrow. A state is environmental if and only if it depends only on the total state of the environment external to the given agent (as it were, the total internal state of the external environment) at the relevant time. The factorising strategy attempts to analyse cognitive states into combinations of narrow states and environmental states (likewise for cognitive processes). If the strategy succeeds, it may be tempting to regard the narrow states that emerge from that analysis as the only strictly mental or psychological states, at least for the purposes of cognitive science. If the strategy fails, it will be tempting to regard some broad cognitive states as themselves strictly mental for the purposes of cognitive science. Internalism is here the …