In this world, much unintended harm is inflicted.

We create a false dichotomy. You are asked to choose a tribe: the insensitive, always-offenders; or the over-sensitive, never-offenders. But there is a middle way.

What does Jon Postel's law tell us? Be conservative in what you do, be liberal in what you accept from others. This principle about API and protocol design can help inform us on how to interact with each other. Applied to the topic of giving and taking offense, the principle tells us that our aim ought to be to not offend and to not take offense.

Though it seems oceans away, interlinked with this principle is another, the principle of charity.

The principle of charity or charitable interpretation requires interpreting a speaker's statements in the most rational way possible and, in the case of any argument, considering its best, strongest possible interpretation.

Put differently:

We make maximum sense of the words and thoughts of others when we interpret in a way that optimizes agreement.

When Jon Postel was designing TCP, why did he recommend "to be liberal in what you accept from others"?

Because making the maximum sense of the system is furthered by interpreting what you receive from others in a way that optimizes agreement. Although no amount of disagreement will hurt the feelings of a congestion control algorithm, it can certainly increase packet retransmissions, packet loss, and other Bad Things. This conclusion equally applies to human communication.

Principally, this is most interesting as applied to resolving apparent deltas of thought. This wording, apparent deltas of thought, seems a bit clumsy — and perhaps it is — but I use it to avoid words with subtly different meanings, such as disagreement or misunderstanding. I avoid these words because they have a connotation of finality. That we aren't actively working towards convergence. (Or at the least, working towards convergence in the sense that we understand each other's apparent delta in thought.)

The principle of charity has a beautiful symmetry. It states how to receive communication, but its implicit normative dual is about transmitting. Not only should you receive communication in the most charitable way, but you should also communicate in a way that optimizes the likelihood of a charitable interpretation.

One of the most important tricks I've ever learned is how to convert apparent doubt, disagreement, and misunderstandings into a question about the crux of why I think I might disagree. Usually there is an assumption, a fact, a goal, or something else upon which the decision in question is wholly determined. If I can identify that particular thing, I can assume my understanding of it is flawed, then ask the question. By asking a question, I maximize a charitable outcome: Maybe I'm missing context. Maybe they're missing context, and don't know it yet. Either way, we'll find out.

There is never a reason to not apply the principle of charity. It always optimizes better outcomes.