Here's why:
* Self-awareness: Humans possess a level of self-awareness that allows us to reflect on our own thoughts and behaviors, including our use of language. This self-reflection is crucial for the development of complex language.
* Metacognition: This ability to think about thinking, or metacognition, enables us to analyze the structure and meaning of language, identify ambiguities, and create new linguistic constructs like metaphors, similes, and irony.
* Recursion: Language allows for the embedding of sentences within other sentences, creating infinitely complex structures. This recursive property is essential for expressing complex thoughts and for reflecting on language itself.
* Other Communication Systems: While animals do communicate, their systems are generally limited to expressing immediate needs and desires. They lack the capacity for the abstract, recursive, and reflective qualities found in human language.
Therefore, reflectivity is not a unique property of human language, but a crucial aspect that allows it to transcend basic communication and facilitate complex thought and analysis.
However, some argue that reflectivity might be more developed in human language compared to others. While chimpanzees can learn sign language and demonstrate basic understanding of symbols, they haven't been shown to exhibit the same level of meta-linguistic awareness as humans.
Ultimately, while reflectivity is not unique to humans, its advanced development in human language is key to its complexity and power.