Utilitarianism mission is: reduce pain, increase happiness of the greatest number of people.
Let’s imagine this scenario: We find a new technique, such that we turn everybody in content and happy people. We are all made dumb because it’s easier to be happy when you don’t think as much.
There is something wrong and absurd here. Some intuition that we wouldn’t be happy, if a situation like this occurs. Let’s suppose that happiness does only exist as the lack of pain. Thus, we have to make people happy and content – but they also have to suffer occasionally. So, to maximize happiness, we have to induce suffering – this seems to contradict the point above: reduce pain, increase happiness.
A utilitarian might object to this in multiple ways:
1) This is not a contradiction. If pain leads to greater happiness than without it, then this fits into the general scheme.
2) You only make this objection because you know the difference. If we are all born happy and content, then we don’t know what we are missing, so we can’t be unhappy.