There are lies, and there are lies, and the intent is largely the difference. Compassion leads us to try to speak truths that others can experience, within their limits, not to overwhelm them "because it is the truth". Speaking the truth about porno to a nine-year-old is untrue even though the teller details "facts".

It is important to remember, IMHO, that we are dealing here iwth live human communications, not academic papers or arbitrary standards of so called "objectivity".

It is terribly important to be true to yourself, to be able to know what you know and to see what you see. But this does not mean you must blindly spout all the facts you know to anyone at any time. It is not good communication to do so. Just because something can be said to be true, does not mean it is the right thing to say to a given person at a given time.

Who you are speaking to, and what you intend to do, are key elements. A compassionate person prefers the truth, generally, because on the whole honesty is better than dishonesty. I would say that courage, integrity to what you know, and compassion are far more important than subscribing to a moral code that says you must say the whole truth at all times to anyone. But with people of good will it is generally the most helpful way to go.