Luhmann has been criticized for defining communication too narrowly, not taking into account nonverbal communication or nonlinguistic communication. We can ask, for instance, does a baby’s cry count as communication? It seems that the cry would only count as communication if someone else could cry back and be understood by the baby. In this case, the baby and the other person could carry on a conversation, which means a communication system emerges. The same applies to nonverbal forms of “communication” such as sighs, yawns, screams, grunts, facial expressions, “body language,” a slap or punch or kiss, the silent treatment, etc. If two people could carry on a conversation through any of these nonverbal means, this would count as communication. A sigh or grunt has too many possible interpretations–it is too complex–to work as communication. If communication is to work at an appropriate speed (in real time), an utterance has to have a relatively narrow range of legitimate interpretations.
When adults hear a baby cry, they say things like “She must be hungry, or tired, or wet . . .” Someone else can then respond. This is the start of actual communication. The adults are ascribing meaning to the cry; the cry becomes the topic of communication. Or we can say a yawn means that someone is tired or bored. In this case, the yawn becomes the topic or theme of communication, just like the baby’s cry.
One person (ego) can say “The baby is hungry” while being aware that alter might have a different interpretation of the cry. This is the social dimension of meaning–the awareness that others may see the world differently. Ego can never know what alter is thinking due to operational closure of psychic systems. In other words, there is no intersubjectivity.
Similarly, many pet owners claim to be able to communicate with their pets. Clearly, a dog, for example, can tell us when he is hungry or needs to go outside or when a stranger is coming up the sidewalk, etc.. However, unless we can talk back to the dog in the same way (by barking, scratching on the door, etc.) and be understood by the dog, there is no actual communication as understood within social systems theory.
Sign language does, of course, count as communication because it is a two-way, reciprocal interaction. This principle applies when apes or chimpanzees taught to communicate with sign language because the human also uses sign language. Thus, sign language can be considered a form of verbal communication, as can writing. In both cases, there is a standardized system that narrows the range of legitimate interpretations. However, this doesn’t mean that individual apes or chimps can communicate because only communication systems can communicate.
The main point is that individuals (adult humans, babies dogs, cats, apes) do not communicate; only communication systems communicate. Communication is not an action, like walking, that one person or animal can carry out.