When the movie Aladdin came out my kids came up with a game they played at recess with their friends. One person would be the “genie”, all the other kids were the “wishers”. The goal for the wishers was to come up with a wish that the genie couldn’t mess up (without getting too longwinded), and the goal for the genie was to come up with a way of giving them exactly what they asked for- in such a way that it would make them miserable.
Once I heard about it, I have been telling all the magick users I know that this is a great training practice, because magick has a tendency (like computers) to do what you asked for, rather than what you THOUGHT you asked. You have to look at all the possibilities, and figure out all the ways a working might go wrong before you actually set the energy working.
I cannot stress too strongly how we need to be both imaginative and precise when we are dealing with “changing the universe through our will”. This is also a big part of divination- learning to ask the right question to get the response, the information you need to get. We need to know what we need before we can ask for it.
Another way some of us deal with this issue is to place it into the control of a “higher power”: angels, gods, one’s higher self, some entity who is supposed to have both more information, and our best interests in heart. This is usually done by those who feel that it is the higher powers who are the source of energy for what we are doing. When you have turned control over to the Divine, you may not need to know what what you need: “This or something better, for the greatest good for all” is a frequent ending when we are requesting divine help so that we don’t accidentally hurt someone because we didn’t anticipate that result.
We hope that those who we are asking for help don’t feel put-upon, like Genie in the Disney movie. I will point out that while it makes sense to ask help from someone who has the ability to do whatever it is, that it’s not a good idea to simply look up which ever god, angel, saint, loa, or whatever and ask them to power our working. Do you ask for help from strangers walking past your house to carry your boxes when you’re moving? No, you ask your friends- good friends. So create your relationship with divine beings strong first, before you ask them for help (feel free to give them “pizza and beer” after, or whatever they prefer). It depends on your relationship- if if the one helping you is far more powerful, show appreciation in the way you’d show it to a parent or patron. You’ve created a relationship, which implies an exchange, perhaps not equal, but mutually acceptable. I don’t know any supernatural helpers that like are someone you look up on Craig’s list you can pay to “do a job” for you.
Bottom line: while we may or may not “need to know what we need” (depending upon whether we are getting help or not), I think it’s clear that we frequently don’t know what we need. But we can figure it out- with a lot of work, and a little divination.