"In many ways, large and small, as we live our lives, we find ourselves confronted with a brute fact about how little we can know about our futures, just when it is most important to us that we do know. For many big life choices, we only learn what we need to know after we've done it, and we change ourselves in the process of doing it. I'll argue that, in the end, the best response to this situation is to choose based on whether we want to discover who we'll become.
Unless you've had the relevant experiences, what it is like to be a person or an animal very different from yourself is, in a certain fundamental way, inaccessible to you. It isn't that you can't imagine something in place of the experience you haven't had. It's that this act of imagining isn't enough to let you know what it is really like to be an octopus, or to be a slave, or to be blind. You need to have the experience itself to know what it is really like.
This brings out another, somewhat less familiar fact about the relationship between knowledge and experience: just as knowledge about the experience of one individual can be inaccessible to another individual, what you can know about yourself at one time can be inaccessible to you at another time."
- L.A. Paul