Hume’s Regularity Theory

c is a cause of e iff

1. c is spatiotemporally contiguous to e
2. c precedes e in time, and
3. All events of type C are followed by an event of type E. (constant conjunction)

• Constant conjunction = regular relationship between two types of events

• What count as a constant conjunction?

  • Mill: regularity + law of nature
  • Mackie’s INUS (insufficient but non-redundant part of an unnecessary but sufficient condition)
  • Probabilistic dependence

Type vs. Token causation

• Type causation
  • Smoking causes cancer
• Token causation
  • Bob’s smoking habit was a cause of his cancer.
• This course concerns only type causation (token causation is more difficult)
  • see Halpern, Actual Causality

A crash course in Probability

Expressing constant conjunction with random variables

• Random Variables represent attributes of objects/units in question
  • X for height, Y for weight, etc.
  • X=150: an event that a subject’s height is 150cm.
  • Event: RV assuming a particular (range of) value.
    • Weather=Sunny is an event that today is sunny.
• Constant conjunction w/t random variables
  • Event C=c is followed by event E=e
  • e.g. Weather=Sunny is followed by Temp=warm