How can I persuade my audience that white lie is bad?

OK, here's a brief, workable answer. To convince your audience that a "white lie" is bad you need to have an absolutist ethical stance. That is to say, you must have a reason why it is wrong and that reason cannot be based upon circumstances.

The reason must always be valid and cannot change. Circumstances change, but your answer must be absolute to meet your criteria. Your audience will think (or say), "But what if this circumstance was added?"

If you can imagine a circumstance that invalidates your argument, then no conditional, circumstantial argument can be absolutely persuasive. You're reduced to hoping that your audience will agree with your ethical posture in the circumstances you describe without relating to other possible complications/circumstances. One way is a theistic approach.

If a lie is absolutely wrong according to God in a religion and one is a believer, then the person is constrained by their faith. (Note by an example above that Islam makes a provision for lying ... more.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.