According to the Doctrine of Double Effect (DDE), there is a
morally significant difference between (i) the consequences of an action
that were intended by the agent and (ii)
the consequences that were not intended, but are merely foreseen side-effects of the action.
More precisely, according to the DDE, if the consequences of
an action include a state of affairs S,
and S is in the relevant way a bad state of affairs, then (other things
equal) the action is worse if it is
the successful execution of an intention
to bring about this state of affairs S
than if S is merely foreseen (and not intended) by the
agent. Being the successful execution of a bad
intention of this sort is a bad
feature of an action – the sort of feature that can make the action
impermissible, or can at least make an impermissible action more seriously wrong
than it would otherwise be.
In my view, the DDE is entirely true. But the DDE has been
attacked on many fronts. One of these attacks certainly raises a fundamental
problem that any full defence of the DDE must solve – namely, the “closeness
problem”, which was originally raised by H. L. A. Hart in “Intention and Punishment”, and has since then been discussed by many philosophers, such as Philippa
Foot, Warren Quinn, and Jonathan Bennett, among others.
More recently, however, a different sort of
attack has been launched by Judith Thomson (“Self-Defense” in Philosophy & Public Affairs 1991,
and “Physician-Assisted Suicide” in Ethics
1999). This attack on the DDE has now received a whole-hearted endorsement
in T. M. Scanlon’s book Moral
Dimensions (Harvard UP, 2008). However, Thomson’s attacks on the DDE seem to me to
be completely misguided. In this post, I shall examine one of her objections,
and then I shall explain what is wrong with it.
Out of all of Thomson’s objections to the DDE, the one that I
shall consider here is the following (“Self-Defense”, pp. 293-95):
Suppose that Alfred intends to
kill his wife, but by mistake he gives her a drug that in fact saves her life.
Surely Alfred’s bad intention does not make it wrong for Alfred to give his
wife the drug that saves her life! This supports the thesis that quite
generally “intentions are irrelevant to permissibility”; and as Thomson claims,
“if that thesis is true … the DDE collapses”.
1. There are at least two serious problems with this argument.
First, as I formulated it, the DDE implies that it is a bad feature of an action
if the action is the successful execution
of a bad intention. But in the case that Thomson asks us to consider, Alfred’s
action is quite obviously not the successful
execution of a bad intention – on the contrary, his action produces the
very reverse of what he intended, since his action saves his wife, when he
intended it to kill her!
So prima facie, it
is hard to see how this objection can get a grip on the DDE at all. Moreover, since
the difference between intentions that are successfully executed and those that
are not successfully executed seems likely to be a morally significant difference, it is clear
that our intuitions about cases in which someone fails to execute a bad intention cannot go very far to support to such
a sweeping thesis as Thomson’s claim that “intentions are irrelevant to
2. Secondly, it is not clear that Thomson’s thesis that “intentions
are irrelevant to permissibility” is incompatible with the DDE anyway. Thomson formulates the thesis as follows:
It is irrelevant to the question
of whether the agent may do A what
intention the agent would do A with
if he or she did it.
But does the DDE really have to deny this thesis? Suppose that it
is true of you that if you did A, you
would do it with a bad intention. Must the DDE then say that you may not do A? Surely the answer is No. What the DDE
must say is merely that you may not do-A-with-this-bad-intention;
it need not say that there would be anything wrong at all with your doing A with a different intention.
Now, some people may complain that this response to Thomson conflicts
with a certain widely-accepted rule of inference – namely, the rule that the conjunction of “If you were
to do A, you would in fact be doing B” and “You may not do B” entails “You may not do A”.
But in my view, this rule of inference is completely invalid.
Indeed, this rule of inference licenses an objectionable sort of bootstrapping – since according to
this rule, a certain purely counterfactual truth about the agent is enough to
fix what the agent ought to do, regardless of whether this counterfactual truth
ought to be true of the agent or not.
In my view, the most that follows from “You ought not to do B” together with “If you were to do A, you would in fact be doing B” is the disjunction “Either you ought
not to do A, or you ought not to be such that if you did A, you would be doing B”.
What is curious is that Thomson herself seems to
agree with me in rejecting this mistaken rule of inference (p. 294). However, she
fails to see that without this mistaken rule of inference, there is absolutely no
reason to think that the thesis that “intentions are irrelevant to
permissibility” (as she formulates it) is in any way incompatible with the DDE.
As I noted above, I believe that Thomson's other objections to the DDE are equally misguided (as is Scanlon's endorsement of these objections). I shall try to find the time to explain what is wrong with Thomson's other objections at some later point.