↑Goodman M., Tagle D., Fitch D., Bailey W., Czelusniak J., Koop B., Benson P., Slightom J. (1990). "Primate evolution at the DNA level and a classification of hominoids". Journal of Molecular Evolution30 (3): 260–266.
↑ Alasdair MacIntyre, Dependent Rational Animals: Why Human Beings Need the Virtues: "[Language] is insufficient for human rationality, What is needed in addition is the ability to construct sentences that contain as constituents either the sentences use to express the judgment about which the agent is reflecting, or references to those sentences" (p. 60).
↑John McDowell, Mind and World: "In mere animals, sentience is in the service of a mode of life that is structured exclusively by immediate biological imperatives." . . . "Merely animal life is shaped by goals whose control of the animal's behavior at a given moment is an immediate outcome of biological forces" (Harvard University Press, 1994), 15; locus in Alasdair MacIntyre, Dependent Rational Animals.
↑ Owen Flanagan, The Really Hard Problem: Meaning in a Material World (Cantabrigiae Massachusettae: MIT Press).
↑Alasdair MacIntyre, Dependent Rational Animals: Why Human Beings Need the Virtues: "Those who have wanted to draw a single sharp line between human and nonhuman animals have commonly laid emphasis upon the presence or absence of language as such, the ability to use and to respond to strings of syntactically ordered and semantically significant expressions whose utterance constitutes speech acts. But this is insufficient for human rationality. What is needed in addition." (p. 60).
↑Nature vs. Nurture: The Miracle of Language, by Malia Knezek. "What about the fact that other animals do not have similar language capabilities? . . . This obviously involves some innate difference between humans and other animals. . . . Other animals do not use any other form of language (i.e. sign language) even though they have the physiological capabilities"; ex Andy Clark, Being There: Putting Brain, Body, and World Together Again (Cantabrigiae Massachusettae: MIT Press, 1997), 208-209).