When unable to see a person’s reaction, 

we need to be even more careful with our words.

When we’re talking with another person, we may inadvertently say something that hurts or bothers the person. Since we’re looking at him we can see his reaction and, hopefully, address any misunderstanding. This process is the nature of conversation: our speaking and then hearing another’s response as we observe his physical reactions. We continue chatting based on these verbal and physical cues.

But when we write—and especially when writing a comment online—we don’t have the advantage of seeing how others react.

Fixated on driving home our point without being able to see the reader’s reaction, we don’t see the hurt expression, the flash of anger. Unable to see these reactions, we have no clue as to the damage our words are inflicting.

And so we plow ahead like a runaway train. Rather, we need to take control of the chaotic situation, and like a good engineer drive the train responsibly and arrive safely. And be a polite one at that.