"Thou shalt not bear false witness against thy neighbour."

"An often trivial, diplomatic or well-intentioned untruth."-- definition of a white lie

Not all lies must be bad. Consider the interrogated patriot or the polite man. The measure of a bad lie is by how much harm is done by its deception. In distorting another's reality, do we eventually hurt them or ourselves? Does all our good intent culminate into something terrible? Examine for example someone who lies and says their check is in the mail. Might they, by withholding the check, contributed to some larger bureaucratic mess? And won't the postmark prove that they have only delayed an inevitable late fee? The positive intent doesn't matter if the effect is still destructive. If we cultivate discord unintentionally, we are still the cultivator. It grows into a disease. The chaotic yield would be far more relevant than the untraceable white lies which fertilized the field; no one would look to stop the virus but would cure the symptoms instead.

But this might stray into the realm of karma or the butterfly effect. It seems ridiculous to think that white lies might eventually confuse our lives significantly. But too many small distortions will eventually warp a thing out of shape. We need to give reality occasional relief so it can be itself, or we would be mislead into oblivion. We bend truth for ourselves as well. Lies are the immediate relief from reality, which must be often maintained by truth. Too many lies, and everything disintegrates. 

"Faith, here's an equivocator that could swear in both the scales against either scale, who committed treason enough for God's sake yet could not equivocate to heaven."-- a Porter

Doublespeak and oath-breaking are the types of lies which seem most harmful and unjustifiable. They immediately occur to mind as a direct offense against the neighbor.

I'm unsure if we should measure a lie's poison by its immediate effects. I don't know if I should always trust a white lie's purity, especially if I don't know what exactly a black lie is. I would say we should avoid lying altogether, but this would be impossible and tedious. We cannot rid ourselves of the lie as long as everything else is so bad.