Mar 16, 2011

The early history of double effect and intention

When philosophers discuss the principle of double effect, they typically trace its history back to Aquinas's discussion of homicide in self-defense. There, Aquinas claims that the killing of one's assailant is outside one's intention (praeter intentionem).

While Aquinas's discussions are no doubt extremely influential in the development of subsequent ethical thought on double effect, seeds of the principle can be found much earlier in the history of philosophy. I'll mention a few examples.

First, consider Augustine's free will theodicy. The existence of evil is compatible with God's goodness, according to Augustine, because God's tolerance of evil is necessary for the free agency of human beings. God tolerates evil but does not will it. Essentially, Augustine is using double effect reasoning to account for the permissibility of God's creation.

Second, consider Proclus's account of evil. "Evils are not the outcome of goal-directed processes, but happen per accidens, as incidental by-products which fall outside the intention of the agents." [1] Again, we find a distinction between what someone has as a goal, purpose, or intention, and what is brought about by the agent but is in a certain sense beyond the agent's intention. This distinction in Proclus is part of an account of agency, rather than part of an ethical principle (as it is implicitly in Augustine, and explicitly in Aquinas). 

It's useful to trace Proclus's view even earlier back, to Aristotle's remarks on "mixed actions" (Nicomachean Ethics III.1). A captain would never voluntarily throw cargo overboard "without qualification," though he may voluntarily do so to save the passengers on his ship.[2] Throwing the cargo overboard in itself is not choiceworthy-- would not be part of the content of the agent's intentions-- but throwing it overboard to save the passengers might be intended. 

I don't think it's anachronistic to see Aristotle's remarks on mixed actions as a kind of prototype for later thought, in Augustine, Proclus, Aquinas, and Anscombe, on intentional action. Indeed, it would seem that the germ of Anscombe's insight that actions are intentional under descriptions can be found already in the Nicomachean Ethics. (Anscombe is constantly referring to Aristotle in Intention, especially when discussing the practical syllogism, and she also mentions his discussion of 'choice' rather than her preferred 'intention' in a footnote in sect. 40.)

These are just a few of presumably a great number of interesting episodes in the history of action and ethics.

[1]  (De mal. § 50.3–9, 29–31, transl. by Opsomer-Steel 2003, as quoted in the SEP "Proclus" entry by C. Helmig and C. Steel)
[2] Quotes here are from the second edition of Irwin's translation.