His may be the best explanation of what went wrong with this society.

Indeed, he often thought that might be the best explanation of all.

What is the best explanation scientists can come up with?

That's actually correct; science simply provides the best explanation possible given the available data.

That seemed the best explanation for everything Blade had seen here.

It was the best explanation he could come up with.

"This had better be the best damned explanation of your life, Doctor."

Seems like the best possible explanation for all the socks I've lost over the years.

But is your conclusion really the best possible explanation for the evidence?

In fact, based on the evidence, it's the best explanation for what happened.