More than us.

It is hard to draw a line of causality past a few leading events. I bought a sandwich because I was hungry, but I also haven't had a sandwich in a while, and I went to the specific place because I remember it was good. Many things happen because of many reasons, but we like to see a few that make the most sense for us.

Physics is great to invoke for this because obviously things happen because of something else, but there does not need to be a purpose. Two topics lend themselves to this discussion well, quantum mechanics and cosmology--two fields that are ever more entwined each year.

The uncertainty principle is much lauded and has created many useful inventions in technology and physics, but is misleading when expanded out from the quantum world. Do we change the world by looking at it--observing it? Not necessarily. We need to carefully examine what occurs when we "observe" things in the quantum world.

Electrons encase atomic nuclei in clouds of probable energy states as described through Schrödinger's equations. When we look at these electrons, we can use a high energy photon to find it's location, but change its momentum--so our observation changed the electron's behavior greatly! Well, our method of observing changed the electron's behavior. If we were not present and a random photon bumped into the electron, a similar result would occur--we wouldn't know, but there is no reason to expect human consciousness to change the electron's behavior when it is the photon that does so.

Does the moon exist when we don't look? This is an obvious exaggeration of this occurrence, but it serves well to show my point. Obviously the moon will always exist--it is a mass of atoms that are all localizing each other so there is no room for quantum unpredictability. Let's imagine it acted as one large particle that needed to be "observed" to exist. You close your eyes at night, look up, and open. There is the moon. Did it just start existing the minute you opened your eyes? No--you see it right as your eyes open, but light takes a second to go from the moon to Earth. This would mean that the moon would have had to exist a second before you opened your eyes and know exactly when to localize to a specific point, and similarly it would cease to exist a second before you closed your eyes. If its existence depended on when the photons hit your eyes, you could look at the moon and close your eyes for a second, then open them, and you wouldn't see the moon for a second, which obviously does not happen.

The point of this is that things happen outside of our actions and the quantum world is not beholden to us. We CAN affect things with our actions, but it is not solely our actions that affect the quantum world.

As for cosmology--as far as we know the universe exists and in such a state that we are able to live. There does not need to be a purpose for all of this, but it is not difficult to see how it could be probable for there to be an underlying purpose.

In summary things happen for a reason, but those things are not dependent on us.