Sidgwick's Criticisms of Mill's Proof of Utilitarianism

Sidgwick's Criticisms of Mill's Proof of Utilitarianism 
Ok, apparently I can only write if it's in my blog so, instead of staring at a blank screen trying to rewrite my paper, I'll write down the basic ideas up in herr first.

Here we will examine Sidgwick's criticisms of Mill's Proof of Utilitarianism.  With that in mind, it will probably do some good to lay out Mill's (in)famous proof which I've done in more detail elsewhere.  I'm too lazy to figure out how to put a link to it but it was last month.  What I've laid out below should be sufficient for our purposes.  But first a lets clarify the terminology...

Definitions
Utilitarianism:  From the most general point of view utilitarianism is a consequentialist theory, which means the the goodness/rightness or badness/wrongness of an action/thing is measured according to the consequences it produces.  More specifically, it is the moral theory that the 'rightness' of an action is measured in direct proportion to the happiness it produces.  In other words, if you want to know how 'right' or 'good' an action is, you need to count up how much happiness it produced.

Happiness:  Generally speaking, Mill equates happiness with pleasure or diminution of pain.


Moral good: is what ever the ultimate end our actions is (ought to be?)--that is, happiness.

Mill's Proof of Utilitarianism
The utilitarianism is about ultimate ends--and that end is happiness.  To prove that something is an ultimate end we need to determine if that thing is desirable.  The principle that Mill seeks to prove is that "happiness is desirable, and the only thing desirable, as an end; all other things being desirable as means to that end."

Mill's conclusion about happiness being the only desirable end can be divided into two main sections.  The first is to prove that happiness is an end, and second that happiness is the ultimate end.  Since knowing whether something is an ultimate end depends on whether it is desirable, the proof will require establishing that happiness is not only desired and an end but is the only thing desired as an end.

With this in mind, lets lay out the first part of the proof:
(P1)  The only evidence that something is desirable (i.e. good) is that people desire it.
(P2)  People desire their own happiness.
(P3)  Thus, a particular person's happiness is desirable to them (and therefore an end),
(P4)  Thus, happiness (as conceived by each person) is an end and (therefore) a good to that person.
(C1)  So, the general happiness is a good to the aggregate of all people.

Up to here Mill's given a proof for the first half of what he needs--that happiness is desirable as an end.  But he still needs the second half of the proof--that happiness is the only thing desirable as an end, and that all other things are desirable only in so far as they are a means to happiness.

This argument I've covered this in a previous post so I'll go though it quickly.  The basic idea behind this part of the proof is psychological hedonism: the idea that all possible objects of desire are in fact merely a means to happiness or a component of a compound notion of happiness.

The argument goes like this:  Sure it's true that people desire things other than happiness such as virtue, fame, honour, power, and so on, but they only desire these things because they are means to achieving the ultimate end of happiness.

Someone might reply that, wait, that's too easy.  You're just defining the problem in such a way that your desired conclusion isn't falsifiable.  To this Mill introduces the compound notion of happiness.  This is the idea that different things can be included in different people's notion of happiness.  Sure, he says, there are things like virtue that you pursue in their own right from which you do not expect a happiness pay-off.  But what has happened is that being virtuous has come to be included (by habit and/or education) in your concept of happiness.  Now, unless you live virtuously, you will not be able to be happy.

So, virtue-- just like eating donuts--has come to comprise the cluster of things that are contained in your concept of happiness.  By desiring virtue as an end, you are not desiring something distinct from happiness because virtue is just an aspect of happiness for you.  Finally, with psychological hedonism Mill has proven the second half of the conjunction:  (C2) since everything either is desirable as a means to happiness or is contained within it, happiness is the only thing desirable as an end.

Lets turn to Sidgwick's criticisms of Mill's proof.

Sidgwick's Criticism of Mill's Proof

Argument 1: The Aggregation Step
Sidgwick's first criticism concerns Mill's aggregation step which is the move from (P4) to (C1).  The general argument is that just because individuals desire their own respective happiness it does not follow necessarily that the aggregate of people (i.e. humanity together) desires the general happiness.  If there is no desire for the general happiness, then it cannot be and end nor a good.

Lets grant Mill that everyone desires their own happiness and that their particular happiness is a good to them.  Now consider two people, Bob and Mary, who live on an island.  Bob desires his own happiness and considers it a good and Mary desires her own happiness and considers it a good.  If we somehow add together their concepts of happiness into a "general happiness" it does not follow that Bob and Mary desire the general happiness; in fact, they (still) only desire their particular happiness.

Neither Bob nor Mary necessarily have a desire for the general happiness.  Add together happinesses on a society or world-wide scale and the problem becomes even more pronounced--people's desires for happiness only correspond to their own.  Since no individual desires the general happiness (just their respective individual happiness), there exists no desire for it, so--contra Mill--the general happiness is not an end, and therefore not a good.

Argument 2:  Fallacy of Equivocation
The fallacy of equivocation is committed when a key term (that has more than one meaning) doesn't maintain a consistent meaning throughout the argument.  Mill tells us in (P1) that we can know what is desirable by observing what people desire.  He uses an analogy to make this point:  the proof that something is visible is that people see it, and the proof that something is audible is that people hear it.  So, it follows that we can know that something is desirable if people desire it.  But the analogy doesn't work.  'Desirable' doesn't usually mean 'able to be desired', it usually means that there is something we ought to desire or that is worthy of desire.  In short, it is usually employed as a normative term, but 'able to desire' is a descriptive term.

So, what's the problem?  Well, Mill's conclusion--utilitarianism--is a normative theory; it purports to tell us that we ought to desire the general happiness.  But his supporting premises contain 'desirable' in the descriptive sense, i.e., (P2) people do desire their happiness.  Therefore, Mill is not justified in  arguing for a ethical conclusion from psychological facts.  More generally stated: the proof suffers from the fallacy of equivocation because 'desirable' isn't used consistently throughout the premises and the conclusion.

Argument 3:  Vs Psychological Hedonism In order to prove (C2) that happiness is the only thing desirable as an end, Mill appealed to psychological hedonism: i.e., the theory that all possible objects of desire are in fact either a means to happiness or a component of a compound notion of happiness.  Sidgwick rejects this psychological model and consequentially the conclusion (C2) that follows from it.

Lets do a quick analysis of Mill's psychological model.  For Mill, the relationship between "desiring a thing and finding it pleasant" is one of equivalence; "they both name the same psychological fact" (Mill, pp. 125-126).  But is this true?  Perhaps, if by decree we define our words this way, but this semantic equivalence doesn't accord with common or psychological usage.  Sidgwick suggests one possible disequivalence is that phrases like "at his pleasure" or "as he pleases" denote something akin to voluntary choice rather than the chooser's objective being some "prospective feeling" (Sidgwick, p. 44).

Butler psychological model suggests a more extreme disequivancence between desiring a thing and finding it pleasant.  On his model, we necessarily desire things other than pleasure.  Pleasure is the consequence of pursuing things like honour, power, and virtue.  If we do not already have the additional desire for (in addition to the desire for pleasure)  the thing that gives us pleasure, we can not pursue the pleasure (quoted in Sidgwick, Ibid).  

While Sidgwick doesn't endorse Butler's view that we could never pursue pleasure at all without first desiring some other object, he agrees with the general point against Mill:  Not all of our desires are directed at pleasure.

So, if we accept some version of this psychological model it is not clear that everything we desire we also will find pleasant.  It then follow that  (C2) cannot be derived from the proof--i.e., happiness might not be the only desirable end.