Deductive- Nomological Explanation

Although the D-N model of scientific explanation is not considered valid in its own right, it is often a convenient departure point for people developing theories of explanation. I thought it would be interesting to consider how different theories of consciousness fit in with this model of scientific explanation.

The basic idea of Deductive-Nomological explanation is that: - an event or generalisation is explained by derivation from laws of nature and background conditions - i.e. given laws L1, L2, L3, etc…and background conditions C1, C2, C3, etc… we can deduce that E (where E is a statement of the explanandum)

An example of a scientific ‘D-N’ explanation might therefore be the following:

  • E = mc^2
  • 1 gram of mass was converted to energy
  • Therefore, 9*10e13 J were produced.

Problems with the D-N model:

  • Heavy reliance on laws of nature - if there are no laws, there will not be valid scientific explanations
  • Problem of unique causes - i.e. if an explanandum has only one possible cause, one could infer from the occurrence of the explanandum, that the cause occurred. This puts things the wrong way around.
  • Problem of side effects - i.e. if a particular event E always causes two separate events A and B, then we could infer from the occurrence of A that B occurred. But A did not actually cause B!
  • Problem of pre-emption - i.e. if cause C guarantees an event E, but something happens before cause C that results in the occurrence of E, then the cause C doesn’t seem to explain the event E.
  • Problem of irrelevant conditions - i.e. if Bob takes birth control pills and does not get pregnant, we can cite the ‘law’ saying that nobody who takes birth control pills gets pregnant. This doesn’t seem like a valid explanation.

Inductive-statistical explanation:

A slight variation on the D-N model introducing probability. Faces similar problems as the D-N model of explanation.

Relevance to studies of consciousness:

  • if consciousness is fundamental, would we have any ‘laws’ for working with this concept? If not, could the D-N model of explanation be applied at all, since there would be insufficient law statements to provide a complete explanation?
  • do any theories of consciousness operate under a D-N or I-S (inductive-statistical) model of scientific explanation?


  • Salmon, W. (1989) Four Decades of Scientific Explanation
  • Salmon, W. (1989) Four Decades of Scientific Explanation
  • Hempel, C. Laws and their Role in Scientific Explanation