relevant experience. As children, we heard instances of the full form and the reduced form, but we were not instructed to avoid the reduced form in certain places; we had no access to "negative data," information about what does not occur. Plato's Problem particularly refers to a point in the dialogue when Socrates is talking with an uneducated servant and shows, through this interaction, that the servant knows the Pythagorean Theorem though he has never been explicitly taught any geometry. How does the servant know without having ever been taught? Plato's suggestion is, essentially, that people have innate knowledge. In the field of linguistics, Plato's Problem is the problem of finding an explanation for how a child acquires language though the child does not receive explicit instruction and the primary linguistic data a child does receive is limited. This PLD is the input, or stimuli, from the environment, necessary for the development of an individual's grammar – language – via input into UG. This limited environmental stimulus is referred to as poverty of the stimulus. Specifically, the stimuli to which children are exposed during the critical period do not encompass every lawful example of grammatical structure relevant to the particular language. For instance, consider that a child might hear the following examples: Who do you think that Jack will kiss first? Who do you think Jack will kiss first? From this, the child might determine that the word that is optional and from this analogize to the following examples: Who do you think will kiss Jill first? *Who do you think that will kiss Jill first? Clearly, the second example is not a grammatically well-formed sentence in English. A child knows this and does not form sentences such as the one marked by the asterisk. How does the child know, without being explicitly taught, that the ungrammatical example is, in fact, ungrammatical? From the linguistic perspective being described here, the answer to this question is that such knowledge pre-exists as part of UG. Plato's Problem describes the disparity between input (poverty of the stimulus) and output (grammar). As Plato suggests in the Meno dialogue, the bridge between input (whether limited or lacking) and output is innate knowledge. Poverty of the stimulus is crucial to the Platonic argument and it is a linchpin concept in Chomskyan linguistics. For this reason, Plato's Problem is often used synonymously to mean poverty of the