Verified by 
If we met an intelligent alien species, in person, to what extent could we communicate?
This is obviously a complicated question, but I want to take a stab at it by contrasting the perspectives of two different books on linguistics: Metaphors We Live By by George Lakoff and Mark Johnson, and Through the Language Glass by Guy Deutscher.
I don't think either book can be seen as directly contradicting the other. But the first can be used to argue that aliens could be so profoundly different from us that communication might be extremely difficult, if not impossible. And the second can be used to argue that differences, even great ones, can be overcome by patient explaining and clarifying.
Let me foreshadow my discussion with a silly scenario. Let's say a flying saucer lands on my lawn and the alien pilot sticks its head (or whatever it's got) out the window.
ALIEN: Sir, where may we park our spacecraft?
ME (pointing): Over there, in the parking spot by the concrete wall.
ALIEN: I don't understand. Where?
ME: Allow me to explain. Our species uses its upper limbs to
indicate direction. When I move my arm like so, that means you are to extend an imaginary line along its axis until it intersects with an example of the object under discussion.
ALIEN: Thank you kindly, good sir.
ME: You are quite welcome.
This silly little scene encapsulates both of the perspectives I wish to discuss. The first, from Lakoff & Johnson, is that human language is much more deeply rooted in the physical facts of the human body than is commonly realized.
The Pioneer 10 plaque
Lakoff and Johnson explain that as bipedal beings living in a gravity field, we tend to speak of good things as being high and bad things as being low. (Among other things, that may come from knowing that adding to a pile of supplies makes its level go up, and that being low is often the result of falling.) So happiness is up, sadness is down. Consciousness is up, unconsciousness is down. "I woke up. I fell asleep." Health and life are up; sickness and death are down.
Another example is the "center-periphery" schema, which comes from the fact that the most essential human organs are in the center, while the less essential ones are at the periphery. One can lose a leg, but not a stomach or heart. So we speak of core principles and peripheral details, and insiders and onlookers. All of these phrases are metaphors, and they only make sense if you understand how the human body is put together and oriented in space.
Lakoff and Johnson argue that such metaphors, far from being the disposable incidentals of human language, are in fact at its center. They can't be stripped away.
Take the following sentence: "We're taking a gamble." That's obviously a metaphor to a game of chance. So try stripping out the metaphor: "We're taking a risk." But this, too, is metaphorical: risk is conceptualized as something that can be grasped like a physical object. And so on. You can't ever get away from metaphors rooted in the body.
So the problem here is that if aliens have very different bodies, they may also have profoundly different metaphorical systems. What if they're shaped like starfish, with eyes in 360 degrees? What if they've lived in zero gravity for thousands of years? What if they're running as software in computer circuitry and don't have physical bodies at all? It might take quite a while to map one species' deep metaphorical structures onto another's.
So reading Lakoff and Johnson gives cause for concern about the prospects for communicating with aliens who have really weird bodies.
But, on the other hand, in Through the Language Glass Guy Deutscher argues that even when human languages have very different ways of describing reality, understanding can be achieved by the simple expedient of explaining.
For example, in the aboriginal language of Guugu Yimithirr, directions are always given in absolute rather than relative coordinates. A speaker will never say that a bug is in front of, or to the left of, his foot. He will instead say that it is north of his foot, or east of it, or whatever direction it is actually in. In fact, the language doesn't have words for "right", "left", "in front of," or "behind" at all. Speakers only use geographical coordinates.
The results are very strange to those of us who are used to relative coordinates. As Deutscher explains it:
If you are reading a book facing north, and a Guugu Yimithirr speaker wants to tell you to skip ahead, he will say, "go further east," because the pages are flipped from east to west. If you are looking at it facing south, the Guugu Yimithirr will of course say, "go further west" (167).
Bizarre-sounding, indeed. Yet, Deutscher cautions us, "if a language doesn't have a word for a certain concept, that does not necessarily mean its speakers cannot understand the concept" (171).
And it turns out that Guguu Yimithirr speakers have no trouble understanding the English language's idea of relative coordinates when it's explained to them. Just as, for that matter, English speakers have no trouble understanding the Guugu Yimithirr coordinates after it's explained to them.
So this seems to give some hope that intelligent creatures that have very different bodies can still understand each other's metaphorical structures with due explanation. For example:
ALIEN: Good morning, Dr. Chorost. How are you today?
ME: I'm feeling up.
ALIEN (confused). You're feeling...a direction?
ME: As a bipedal species living in a gravitational field, we tend to
associate height with good things.
ALIEN: Why?
ME: Our heads - which we prize - are at the top of our bodies. If we fall our heads can get hurt. So we tend to associate being low with being injured. And being injured is, for us, very bad.
ALIEN: Ah, so I see. My groof bishwaint spilkas for green.
ME: What?
And so the alien explains, and gradually I begin to understand the way of thinking of a species that hasn't lived in gravity for 10,000 years, or hasn't experienced death for five thousand, or whatever the situation may be. My examples are deliberately rather silly, but I hope they illustrate my point.
Two closing thoughts. When people (and by "people" I mean all thinking beings) communicate, they're always communicating about something. Something to exchange, something that needs to get done, something that needs to be explained. One party often wants the other to do something. And that automatically creates a context. It's not like two species would get together just for the purpose of discussing prime numbers. The real difficulty may be in getting a context. What would a species 50,000 years ahead of another one want to discuss with it?
And, on pointing: When I was taking basic ASL I learned that there are very specific ways of pointing in order to give directions. To direct someone to an object that's very far away, one points high and opens one's mouth a little bit. To direct someone to an object that's very close, one keeps one's hand close to the chest and grimaces in a particular way. I'd like to think that such gestures are iconic, not requiring explanation, but the fact is that someone thought they had to be explained to me. I had to take tests demonstrating that I understood them. So it gives me just an inkling of how an intelligent alien might not understand what a pointed finger means.
