In this task, you are given a question and a context passage. You have to answer the question based on the given passage.
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Question: What is needed to prove the theory?, Context: In the early 11th century, the Muslim physicist Ibn al-Haytham (Alhacen or Alhazen) discussed space perception and its epistemological implications in his Book of Optics (1021), he also rejected Aristotle's definition of topos (Physics IV) by way of geometric demonstrations and defined place as a mathematical spatial extension. His experimental proof of the intromission model of vision led to changes in the understanding of the visual perception of space, contrary to the previous emission theory of vision supported by Euclid and Ptolemy. In "tying the visual perception of space to prior bodily experience, Alhacen unequivocally rejected the intuitiveness of spatial perception and, therefore, the autonomy of vision. Without tangible notions of distance and size for correlation, sight can tell us next to nothing about such things."

Answer: vision


Question: Various early things are what kind of content?, Context: Much of the material in the Canon is not specifically "Theravadin", but is instead the collection of teachings that this school preserved from the early, non-sectarian body of teachings. According to Peter Harvey, it contains material at odds with later Theravadin orthodoxy. He states: "The Theravadins, then, may have added texts to the Canon for some time, but they do not appear to have tampered with what they already had from an earlier period."

Answer: teachings


Question: What is not seen as predominant in the US, Context: Broadly speaking, government phonology (or its descendant, strict-CV phonology) has a greater following in the United Kingdom, whereas optimality theory is predominant in the United States.[citation needed]

Answer:
government phonology