Introduction In Plato s dialogue Meno Socrates sets out to convince Meno that we have knowledge without experience He uses a young slave from Meno s household one who has not had any formal education for this purpose Socrates asks the boy questions about geometric shapes that he draws with a stick in the sand Without teaching the boy anything only by asking him questions Socrates elicits the Pythagorean Theorem from the boy that is the square of the longest side of a right triangle the hypotenuse is equal to the addition of the squares of the two other sides Socrates then concludes that knowledge is not taught but is recollection from a previous existence In terms appropriate to today we might say that knowledge is innate that it is carried in our genes Innate Knowledge of Language We can approach the question of innate knowledge of language in the following way Keep in mind that the knowledge we are referring to is not conscious knowledge anymore than the Pythagorean Theorem was conscious knowledge for Meno s slave boy 1 First if we look at the acoustic record of a sentence it is best described as a continuum what we call the stream of speech In the physical record it is just uninterrupted noise However the speaker hearer knows that this noise is a linguistic event and different from other noises The ability to distinguish linguistic noise from other noises is not taught 2 Second the stream of speech is heard mentally not as an undifferentiated stream of noise which it is physically but as made up of distinct phrases distinct words even distinct sounds That is unlikethesentencesonthepagewhichhavespacesbetweenthewordsandpunctuationbetweenphrases andwhereeveryletterisdistinctfrom everyotherletterthestreamofsppechismorelikethisexample Once again we take it for granted that we hear distinct words and phrases when physically we hear a continuous stream of sound and once again when we take something like this for granted it is likely innate That is no one has taught us to analyze the stream of speech into its linguistic components but we do it all the time with sentences we hear for the first time of have heard before 3 Third we can hear the same sequence of words in different contexts and interpret them with different meanings 1 Flying planes can be dangerous 4 Fourth another example from Chomsky in Syntactic Structures points to another kind of innate knowledge Chomsky s Syntactic Structures 2 Colorless green ideas sleep furiously As Chomsky points out this sentence is meaningless nevertheless it is quite different from the same words taken back to front 3 furiously sleep ideas green colorless That is meaning does not determine grammaticality Both 2 and 3 are meaningless but 2 is grammatical This knowledge is not taught but we all know it 5 Fifth consider the meaning of the pronoun he in the following examples Chomsky s Syntactic Structures 4 John thinks he is smart 5 He thinks John is smart 6 Although he studied all night John still failed the test In 4 he can refer to John or to somebody else say Bill or Harry In 5 he cannot refer to John at all Notice that it is not simply that he followsJohn in 4 and precedes John in 5 that determines its interpretation In 6 he precedes John as it does in 5 and still refers to John As we will see in the discussion of syntax in the next module the determination of pronoun reference in sentences like 4 through 6 depends on a structural property of sentences that is not taught but must be innate 6 Sixth we know that sentence like 7 and 8 mean the same thing and those like 9 and 10 mean quite different things Chomsky s Syntactic Structures 7 Mary opened the letter 8 The letter was opened by Mary 9 John is easy to please 10 John is eager to please Though the words are in quite a different sequence in 7 and 8 the meaning of who did what is nevertheless the same In 9 and 10 the order of words is the same but the meaning of who will be pleased is completely different This is knowledge that is not taught As a final set of examples consider the following Chomsky s Syntactic Structures 11 Harry will study 12 Will Harry study Sentences 11 and 12 are clearly related the former is an answer to the question in the latter Let us assume that the two sentences are related by a rule A first approximation of the rule is a question is formed by inverting the first two words of a statement This rule will work for deriving 12 from 11 and it will work for deriving 14 from 13 Chomsky s Syntactic Structures 13 He will study 14 Will he study Thus the rule invert the first two words of a statement to form a question is quite good It will work for a very large number of sentences that start with a name like Harry Mary Sarah Bill or a pronoun like he she you they followed by a modal like will can must might would However it will fail for an even larger set of sentences like the following an asterisk indicateds the sentence is ungrammatical Chomsky s Syntactic Structures 15 The student will study 16 student the will study It seems obvious that a rule can t be based on counting the words in a sentence No one tells children that this is the case And it is not unreasonable to think that counting words might be the basis for a rule of grammar Nevertheless children don t make mistakes like 16 and counting words is irrelevant to grammatical knowledge Thus it appears that Plato s problem how is it that we know so much with so little experience has real bearing on knowledge of language as it does on knowledge of geometry on knowing what we see or even more basically of how the organs of the body know how to carry out their functions While this last case seems obvious the digestive system is a physical system designed to do what it does the knowledge of language or geometry is less obvious For Plato knowledge of geometry had to be recollection of memories from previous existence For us today we see this recollection of memories as in our genetic structure Similarly for knowledge of language we can conclude that untaught knowledge is in our genetic structure As we proceed through the following modules on syntax morphology phonology language change and acquisition Plato s problem will continually come to the fore It is central to the questions of what we know when we know a language and how we come by such knowledge