1. Mill’s proof of utilitarianism
Michael Lacewing

2. Stage 1: happiness is good
You can’t ‘prove’ that something is good or not, but you can give a reasoned argument.
What is good is what we should aim at in our actions and lives.
Good is an end, a purpose of action
Happiness is a purpose of action

3. Desire and happiness
The only proof capable of being given that an object is visible is that people actually see it … In like manner … the sole evidence … that something is desirable is that people do actually desire it … .
No reason can be given why the general happiness is desirable, except that each person … desires his own happiness.

4. Fallacy of equivocation?
Equivocation: using one word with two different meanings
Makes an argument invalid
Moore: Mill equivocates on ‘desirable’
Worthy of being desired (good)
Capable of being desired (what people desire)
Reply: what people desire is evidence for what is desirable (good)

5. Individual and general happiness
This, however, being a fact, we have not only all the proof the case admits of, but all which it is possible to require, that happiness is a good: that each person’s happiness is a good to that person, and the general happiness, therefore, a good to the aggregate of all persons …

6. Fallacy of composition?
Fallacy of composition: attributing some feature of the members of a collection to the collection itself
Because each person desires their own happiness, everybody desires everybody’s happiness (the general happiness)?
Compare: Every girl loves a sailor. Therefore, there is one sailor who every girl loves! No.
Reply: Mill simply assumes impartiality. If happiness is good, then morality concerns the general happiness.

7. Stage 2: only happiness is good
People don’t only desire happiness
Reply: Happiness has many ‘ingredients’, such as truth and freedom, and each ingredient is desirable in itself
The distinction between ‘external’ means and ‘constitutive’ means
To want to know the truth for its own sake is the same as one’s happiness consisting in knowing the truth
It is not possible to desire something that you don’t think is a pleasure