But what if it is proved that a particular animal has such capabilities such as intentions, mind-reading and so on, would we then grant linguistic capabilities to it? As philosopher John Searle put it, "`85. imagine a class of beings who were capable of having intentional states like belief, desire and intention but who did not have a language. What more would they require in order to be able to perform linguistic acts? The first thing that our beings would need to perform illocutionary acts is some means of externalising, for making publicly recognisable to others, the expressions of their intentional states. A being that can do that on purpose, that is, a being that does not just express its intentional states but performs acts for the purpose of letting others know its intentional states, already has a primitive form of speech act."
This is the point animal language researchers are trying to get across to the sceptics. They say that the critics hold it as a logical truth that language capability is found in humans alone. So, no matter how much evidence Savage-Rumbaugh or Penny Patterson might amass, the sceptics will never accept that Kanzi or Koko are actually speaking. Why? Because they are animals.
No one is trying to say that these apes use language with the same dexterity as humans do; certainly they are no match for humans. In the book Apes, Language, and the Human Mind, Savage-Rumbaugh says that although Kanzi is far behind humans in linguistic skills, yet he has shown that he understands abstract concepts, and can understand the meaning behind complex sentences, and can also indulge in playacting and pretending. His favourite pretend game centres around imaginary food. He pretends to eat food that is not really there, to feed others imaginary food. He pretends to find it, to take it from other individuals, to give it back to them, and to play chase and keep-away with an imaginary morsel. He will even put a piece of imaginary food on the floor and act as if he does not notice it until someone else begins to reach for it, then grabs it before they can get it.
Whether Kanzi and Koko have acquired language skills or not, only further research will tell, but their achievements should not be ignored, just becuase they happen to be animals.
http://www.tribuneindia.com/2003/20031109/spectrum/main2.htm