It's not so much that there are no priorities in GTD, in fact priority is probably the most important thing. So important that it's not in the system, it's in your head.
Originally Posted by cwoodgold
If we could rate every goal/ AOF/ Project, maybe "Be healthy" is a 10, "Buy Aunt Betty's birthday present" is a 5, etc then we could make a formula that would result in a priority number. Then, by a complicated method of evaluating how every next action on our list relates to each project and higher level we could calculate the priority of each item. This of course would be ridiculous and it would take the whole day to keep the system going and nothing gets done. This is however what our brains do all the time. The clearer a picture in your mind is about who you are and where you want to go, the more accurate the result from this "brain number crunching".
But I call it the "holy grail" because probably very few people have their higher levels organised to perfection. And I'm glad you said you weren't sure because a) it adds weight to my point but more importantly b) you realise that developing the higher levels is a lifelong process. I reckon that most people who would say they have the higher levels sorted are kidding themselves. You have to test your conclusions against real life and it can probably take a lifetime.
So I would never criticise you for using priorities in your system in the way you describe. Far better that than to force yourself to set higher level goals which aren't really true to you. Let them develop organically, I say.