The Biggest Problem in Communication Is The Illusion That It Has Taken Place.
Who said this? George Bernard Shaw? William H. Whyte? Pierre Martineau? Joseph Coffman? Anonymous? There is some debate on the attribution issue and the version of the same comment. The greatest problem with communication is the illusion that it has been accomplished; The most serious danger in communication is the illusion of having achieved it; The great enemy of communication is the illusion of it. No matter the phrase, communication can be a bitch.
Back in the day, I'm talking about the days perhaps 300,000 years ago, as we were emerging as the modern version of humans. No one knows for sure, but chances are our language was considerably more fundamental than today. We may have made grunting sounds that meant things like; I'm hungry; I'm mad; I'm horny; I'm sleepy; Look out! that sort of thing. We may have had a couple of dozen sounds that we used to communicate; life on some levels was simpler then. Today, there are somewhere between one-half million and one million words.
Add to all these words the diversity of the human species. Men, women, nationalities, education, training, job-specific jargon, experiences, motivation, and self-preservation; there may be thousands of influences that cause us to use specific phraseology and to interpret what we hear. Add, also, the fact that depending on the type of conversation we're in, we may be listening to respond, as in a debate, rather than listening to understand the other person's train of thought.
English is the most spoken language globally and is generally considered the most complex and challenging to learn. And, there are the nuances. Other languages say yes or no. We say that too but also say, maybe, sort of, kind of, in a way... we can answer without actually answering.
Another problem element of communication I've found is that when we explain something to someone else, we often assume the listener has the same knowledge we have. We say things with many blank spots where that presumed knowledge fills in the meaning. We use a kind of verbal shorthand that can leave the listener bewildered. A simple example might be giving someone a baking recipe. You might say, "Take an egg, break it into a bowl, and stir until it's blended." If the listener is an expert baker, they may know the egg needs to be at room temperature, but if not, they may be headed for failure. Does everyone inherently know the egg needs to be at room temperature; is that knowledge universal?
In many ways, the communicator is the teacher. You don't want a room full of students constantly raising their hands to ask questions about what you just said; good communication seeks to be understood, not responded to. You want to see people shaking their heads affirmatively, not frowning and saying, "What?". "Ah, yes" is the response you're looking for.
That last paragraph seems to me to be the key to good communication. In communication, you seek to have other people clearly understand what you are saying. It's different from persuading others to see or think as you do. Good communication requires clear thinking and a goal for the communication; what do you want the listener(s) to understand? Oh, and of course, it requires that you know the topic well and aren't winging it.