Isn't there a strong argument that the actual translation is "Thou shalt not murder?"
I've heard this stated, but I don't have any references. I have some
books that should cover this but the curiously skip over it.
But a very strong answer in such cases comes from the Gospel, for
Our Lord certainly knew the mind of God. And when the woman was
caught in adultery, and the townspeople were going to stone her, what
did Jesus do, but write with his finger in the sand.
He did not say that the death penalty was a bad thing, or that nobody
should ever be executed -- in fact, it was by capital punishment that
He died on the Cross, and unjustly so. But He was not opposed to it
on principle. You know He could have been so opposed to it if He had
known that to be the truth. Therefore, the fact that he did not oppose
it answers the question. He died to uphold the truth.
Taken literally, "Thou shalt not kill" could mean you can't slaughter
animals, or that man was forbidden to sacrifice sheep, goats, oxen,
doves -- Our Lady and St. Joseph provided two doves for their
offering to the Temple priest at the Presentation of Our Lord, the 4th
Joyful Mystery of the Rosary. Were they breaking the 5th
Commandment, by supporting the killing of two doves?
It seems rather obvious that this was not a problem in previous ages,
but leave it to our "enlightened age" to make a problem where there
wasn't one before.
Anyone who has the responsibility of running a real farm knows that
sometimes you have to kill an animal. There is no crime in that. The
priests of the Old Dispensation did not take pleasure in the h0Ɩ0cαųst.
It was serious work, that had to be done to satisfy the justice of God.
So, while we may think that the word "murder" better fits the
sentence, the word "kill" has fit the sentence for a very long time
without any confusion resulting from it. The 5th Commandment could
say, "Thou shalt not kill unless it's in self-defense," but that hasn't
been necessary (for the Bible to include that) for everyone to know
that it's true.
Similarly, "4. Thou shalt honor thy father and thy mother," does not
mean that when they command you to sin you are still bound to obey
them. But where is that in the Bible? Etc.