Aristotle bases his philosophy on ends of situations and the final outcomes of goals. At the very beginning of his book, Aristotle claims that all actions toward any kind of goal produce happiness in some way. He says that these activities that lead to ends are not necessarily what brings happiness; the ends are what bring this happiness.
The key to ends and happiness is desire. Without desire to help get to the necessary ends, happiness will not be achieved and time would be kind of wasted. This “chief good” of desire and passion toward ends is the key to happiness according to Aristotle.
Judgement of good and bad come from experiences, so people may not see the goods of every situation due to personal biases. But coming from experience, how can every action be of good intention? Some actions result in setbacks from the ends that can hinder growth to said ends.
People are different though, and some people may thing certain things are good while other people think those same things are bad. When thinking about this, one could ponder if there is such a thing as “good” or “bad” or true happiness at all if everyone thinks differently about actions.
Aristotle writes that virtue is a key factor of happiness. We, as humans, achieve happiness by setting a goal and making decisions that we think will lead to the most happiness. As autonomous beings, we are virtuous. Understanding virtue and morality is what leads to our happiness in the long run. Our virtue depends upon our soul, which can be rational or irrational; but in the end, it leads us to happiness (whether it is with “good” or “bad” choices).