I was chatting with a friend the other day about how we decide what things are and how we parse the world. I made the statement that the world is hierarchically-arranged, and my friend said that the world might not really be that way, but that I could be imposing that type of organization on it. It's certainly a strong possibility that my biases determine how I organize how I think about the world around me.
But I'll be damned if I can step outside of my frame of reference and conceive of another hypothetical way of looking at the world. We normally form concepts of things that exhibit spatial and temporal continuity. We treat a dog as a unified thing because there's stuff that makes up the dog that is close to itself in space and moves together across time. Same for chairs and glasses and pumpkins and even more abstract things. But it also seems obvious that however you slice and dice the world, whatever you call "things" are always going to be composed of constituent things. And those things are likewise composed of constituent things. A car is made of things like mufflers and wheels and axles, and those are made of smaller parts, and those are eventually made of atoms, and those are made of subatomic particles, and those are maybe made out of even smaller things.
I suppose you could have some sort of Buddhist view where there are no parts or subparts...that everything is just one big unified, interconnected thing. But I don't think you'll get very far in understanding how the world works if you don't partition it in some way and try to figure out how the parts work together to produce the phenomenon you want to understand. Hence the usefulness of reductionism.
And my guess is that if there is intelligent life elsewhere in the universe, to make headway in understanding how the world works, they view it hierarchically, try to determine the best way to segment it into parts, and try to figure out how those parts work together. Maybe I'm just myopic, but I can't even conceive of another way in which they might go about understanding the world.
So I don't think I'm imposing some kind of structure on the world. I think the world really does have the structure and that our brains have evolved to learn to exploit that inherent structure in order to survive better.