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Introduction: Why Investigate Philosophical Issues in Behavioural Science?

Answering broadly philosophical questions about action and about joint action requires reflection on discoveries from the behavioural sciences.

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To discover why people act, individually and jointly. This is the overall aim of the course.

Our premise is that discovering why people act requires multiple methods: philosophical, psychological and formal.

An obstacle is that these three methods—philosophical, psychological and formal—are associated with different theories and the theories seem to be inconsistent with each other.

The Simple Picture of Why People Act

Start with a simple picture that is widely assumed in philosophical and economic theories:

When you act, there are reasons why you act; you know the reasons; you act because you know the reasons; and the reasons justify your action.

Is this true? How can we turn it into a theory? Are there alternative pictures?

Much of what we will study are attempts to answer these questions.

Structure: Two Questions

Here’s the strucure of the course. Two questions. One about individual action, the other about collaborative action:

  1. Which events in your life are your actions?

  2. What distinguishes doing something jointly with another person from acting in parallel with them but merely side by side?

We start with the first question then move on to the second.

We will consider each question from three perspectives: philosophical, psychological and formal.

Although the perspectives are distinct, they are not independent. As things stand, we cannot adequately answer broadly philosophical questions about action, nor about joint action, without reflection on discoveries from the behavioural sciences.

Integration Question

The course centers on a set of Integration Questions:

where there are philosophical, psychological and formal theories which appear to target a single set of phenomena while saying incompatible things about it, we face two questions:

  • are they actually inconsistent?
  • if so: how, if at all, should either or both theories be refined?

These questions pose the Integration Question.

As we will see, apparent conflicts between philosophical, psychological and formal theories arise at the most fundamental level.

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Della Sala, S., Marchetti, C., & Spinnler, H. (1991). Right-sided anarchic (alien) hand: A longitudinal study. Neuropsychologia, 29(11), 1113–1127.
Euripides. (2006). Medea. (M. Collier & G. Machemer, Trans.). Oxford ; New York: Oxford University Press. Retrieved from