I am using "fact" in the most technical sense. For instance, horses have 5 legs is a fact, while elephants are large is an opinion. The difference between a fact and an opinion is falsifiability. It's not like a fact is the irrefutable "truth" - it's simply something that can be demonstrated, irrefutably, to be true or false.

Can you prove out "do not kill" as necessarily true?

That's not what I'm saying. I'm saying that "do not kill" is falsifiable. "Do not covet the neighbor's wife" is not.

> I'm saying that "do not kill" is falsifiable.

I sincerely do not understand what you mean by this. Are you talking about whether the phrase exists?

I also just noticed this from above:

> The difference between a fact and an opinion is falsifiability.

The technical, most essential difference is whether the related proposition is true, is it not? Falsifiability is a requirement to have a chance to reach truth, but it does not guarantee it can be reached, and it does not upgrade an opinion to truth.

No, I am using the literal textbook definition. This is why "a horse has 5 legs" is a fact, while "the universe is large" is an opinion. The problem with the latter is that large is subjective, even if most of everybody would agree it's "true", facts do not require agreement, perspective, or context - they can be demonstrated to be clearly right or wrong. A false fact is still a fact.

So back to the above, there is no subjectivity when a person murders another. By contrast, coveting something (or somebody) is very much a gray scale of subjectivity.

Not much to disagree with here. :)