Is the complete brutal truth justified at the cost of hurting near and dear relationships or is a little falsehood justified to save the dreadful feelings of hurt? Who and how will you decide on what's a "little?"
The fact might very well be that there's no right answer. The significance of truth fades away completely in the face of perspective. What might be an effective device can very well turn out to be an impractical solution. A shadow of doubt will always be cast in the opposite direction of the origin of light. A lack of landing ground does nothing to negate the need for the fall itself.
It might be debated that a genuinely strong relationship should be able to wither a storm and stand firm against the tide of continuous battering of endless waves. But it doesnt recede without leaving a mark for the annals of time.
It also means, that the truth always surfaces and subsequently have the ability to be reconstructed. But what about the truth being stranger than fiction? Strange phenomena have an inherent element of revealing its true nature with surprising alacrity. Strangely, 'surprise' has no bearing upon revealation, its simply a different way of being unexpected, which in turn does not effect the nature of events from happening. Essentially, unexpected does not mean it doesn't happen, it just means the result of reaction is something you haven't prepared for. And it shows.
One who does not get surprised, has had a chance to think over all possibilities and learnt to deal with them. While it does not mean that the resultant dealing is effective and efficient, it does ensure mental preparation.
Some staunch advocates of 'on your face' kind of truth say neither should, nor it could, be told any other way. These folks are generally made up of naive, up and coming, victors mostly. Such group has till then, never even had to face worthy adversaries and go toe to toe with them. So the adamance grows as they hadn't been on the receiving end of it and don't care a lot much for the relation in question.
One other group of people would directly say 'the "so-called" truth' is nothing but a simple tool with the powers who-ever-they-be, to use for atrocities committed against them. This group will always be a little afraid of sorts. Afraid about the unknown. The version of truth is very crushing and unkind.
It appears that there are at least three more classifications, but there's no desire left within to build and extrapolate on them.
Overall, one simple way to decide whether or not to tell the truth is to try and guage the impact your truth will make on the person who's on the receiving end. Whatever be the resultant reaction, good, bad, ugly, not acceptable., compare that reaction with the value you attach to that specific relation.
Everyone does something like this in their minds. "Everyone - all the time."
Many, do not even realize they are doing it. It could be a conscious or a subconscious process, depending on various factor's like the individuals personal value system, their social class, societal environment, victories and losses while growing up etcetera.
The question whether to tell the truth does not stand anymore. Its changed to how important is the value of your relationship with the individual or group AND what are you willing to do for it?
As with most of the freebie's in life, there's a caveat for the philosophy above: sugar coating the truth is fine, lying through the teeth is not.
Some people say, the truth always comes out. If you believe in that and feel burdened by it, you can find some solace in the loophole of time and pray for it to reveal itself only when it will not affect you negatively in tactical as well as strategic environment. Or simply wish for it to come-out after a century and only be known to confìdäntés! ;-)