But I never had a really crisp philosophical explanation of why these three...
Now I finally figured out a clean way to express the underlying insight.
Growth is the change from present possibility into future actuality. It's when the implicit becomes explicit -- when potentials become real.
Choice is the change from future possibility into present actuality. Choice is what happens when out of many possible things that MIGHT happen (in the future), a smaller subset is chosen to ACTUALLY happen (right now, i.e. right after the choice is made, in the perspective of the choosing mind).
That's why those two values are fundamental -- on the abstract level, stripping down to fundamentals and looking beyond human psychology.
Maybe Sartre or Husserl or Heidegger or Deleuze or Merleau-Ponty (or Dharmakirti or Dignaga) or one of those dudes already said that (if so, probably in some different terminology). If so I missed it ... or the import escaped me when I read it.
Proliferating and Paring
For example, consider a plant growing. The whole form of the plant is implicit in the seed. Growth is the explication of this implicate order -- the change from the plant-possibility within the seed, into the actuality of the plant.
But there are many different ways the plant might grow -- the seed doesn't precisely determine what will happen; the determination is made via complex interactions between the seed and the environment. Choices are made, and of the many possible future plants, only some are chosen to be actual.
Growth without choice could be indiscriminate -- it could lead to an undifferentiated flourishing of everything.
Choice pares down the results of growth, leaving interesting structures.
Will, Self, Reflection
I keep talking about Choice -- is this the same thing as free will?
Human "free will" is a particular manifestation of choice; the manifestation of choice within self. (For waaaaaay more depth on self, will and reflective consciousness, read this.)
But this raises the issue of whether, in the addition to the three values of Joy, Growth and Choice, we want to add Self. But this seems a subtle question.
Growth and choice seem fundamental -- they have to do with the proliferation and paring of forms, with the dynamics of possibility and actuality.
Self has to do with reflexivity -- with a system in the world modeling itself. But it's much more high-level and particular than Joy, Growth and Choice.
So if we want to add another value to the core list of three, maybe the one to add would be Reflection. Reflection: appearance of the whole within the part.
However, I suspect this is unnecessary. Because Reflection is an amazingly powerful tool for Growth -- so that when you advocate Growth, Reflection comes along for the ride! And growth leads to intelligence eventually, and Reflection applied to intelligence (as a strategy for achieving Growth) yields Self. And if a universe already has Self, then in order to grow further, it's not going to give up Self, because that would essentially be Shrinkage, not Growth -- because Self, aka Reflection applied to intelligence, is a really good way to foster ongoing Joy, Growth and Choice.
And what about Joy?
Well ... Joy is just ... Joy. Joy just is. As the Buddhists say, Suchness. Making possibilities into actualities, and actualities into possibilities, in a spaceless timeless reality-less reality that is nonetheless more directly and palpably experientially real than anything (any thing).
(Like Sartre and Heidegger and Dignaga and the whole crew...)
I've already said way too much!