In Utilitarianism, Mill proposes that the only intrinsic good is pleasure.
Some can argue that this would merely make humans equivalent to being animals, with the intent to fulfill our own desires.
However, Mill counters this form of argument by stating that no amount of animal pleasure can equal even the smallest of human pleasure. For example, a pig which is constantly fed food cannot compare to a homeless person who can enjoy the sound of classical music (or any music, for that fact).
Any being would choose the happiness which fulfills the highest faculties that being has. Humans would not want to stoop down to the level of contentedness (that is a word) swine would have. In a sense, this can be seen as a sort of human dignity. If you take the previous example about homeless people, it sort of explains why people wouldn’t commit suicide simply because they were sad. It’s an inherent form of human dignity.
Another example: Animals eat simply to obtain energy to continue performing regular activities. Human beings, however, have the capacity to enjoy food in a different sense, by actually savoring the flavor of different foods.
Our professor gave us a simple challenge: next time we eat a burger, we were to take a bite, savor it, and then spit it back out. I could see where he was going with this idea. Obviously, the pleasure of food (for humans, anyway) comes from swallowing the food as much as it is putting it in your mouth. You would feel a bit dejected by spitting it out. Hence, in the words of my professor, “you really would have to swallow to enjoy the experience. If you don’t, it would just be a major let down.”