This is an answer to a "how" question rephrased (incorrectly) as an answer to a "why" question.

First, the "inverse square law" isn't a law in the colloquial sense (like a maximum speed limit law) where the universe is forced to obey it. Instead, "law" is just a conventional phrase indicating what the consensus among scientists is regarding certain observations.

So it's really an answer to the question of "how does [our current observations of how] radiation propagate?": "according to the inverse square law".

Future observations of radiation propagation might run completely contrary to those we've had up to now, and it is scientific explanations that will have to be modified to accommodate those observations.

But the inverse square law does not explain why radiation has been observed to propagate in this way.

For such an answer you'd have to resort to a much grander explanation of the universe, involving all sorts of other theories involving many other observations, back to the big bang, which is not yet fully understood and may never be (even if we assume that the big bang theory itself won't be replaced by some other origin theory in the future, and not to mention what happened "before" the big bang, which may be even more impenetrable still).

But even were there to be some comprehensive "theory of everything" (in the larger sense), that doesn't mean the why of it has been explained, as there'll still be open questions like: "why something rather than nothing?" or "why this universe and not another?"

"But," some may object, "I just wanted to know why radiation propagates as it does, not why there's something instead of nothing." Well, I'm afraid that science can't answer your little question without answering the big questions. Religion or philosophy might, but they're also seen as unsatisfactory to many, so such why questions might never be answerable to everyone's satisfaction.

Harder questions, like those about consciousness, are even less likely to be satisfactorily answered, as touching them immediately lands one in to the morass of assumptions, definitions, points of view, and perspectives.

Half the time people are completely speaking past each other because they've never agreed on or even stated what their definitions or assumptions are, so are going off about two or more completely different things. Consciousness itself is notoriously difficult to define, so when two or more people are talking about something that they "know it when they see it," they're bound to talk past each other half the time, whether they agree or disagree.

Some philosophers are better at setting the ground rules and making their fundamental assumptions and defintions explicit, but they're usually pretty balkanized, and you'll find plenty of other philosophers disagreeing with their assumptions and definitions.

I personally see little hope of this thorny problem ever being resolved to everyone's satisfaction, but there'll surely be plenty of arguing about it until the end of time.