Input: Read this: In higher organisms (like people), these two modes of perception combine into what Whitehead terms "symbolic reference", which links appearance with causation in a process that is so automatic that both people and animals have difficulty refraining from it. By way of illustration, Whitehead uses the example of a person's encounter with a chair. An ordinary person looks up, sees a colored shape, and immediately infers that it is a chair. However, an artist, Whitehead supposes, "might not have jumped to the notion of a chair", but instead "might have stopped at the mere contemplation of a beautiful color and a beautiful shape." This is not the normal human reaction; most people place objects in categories by habit and instinct, without even thinking about it. Moreover, animals do the same thing. Using the same example, Whitehead points out that a dog "would have acted immediately on the hypothesis of a chair and would have jumped onto it by way of using it as such." In this way symbolic reference is a fusion of pure sense perceptions on the one hand and causal relations on the other, and that it is in fact the causal relationships that dominate the more basic mentality (as the dog illustrates), while it is the sense perceptions which indicate a higher grade mentality (as the artist illustrates).
Question: What is the purpose of symbolic reference?

Output: links appearance with causation in a process that is so automatic that both people and animals have difficulty refraining from it

Input: Read this: In nature, uranium is found as uranium-238 (99.2742%) and uranium-235 (0.7204%). Isotope separation concentrates (enriches) the fissionable uranium-235 for nuclear weapons and most nuclear power plants, except for gas cooled reactors and pressurised heavy water reactors. Most neutrons released by a fissioning atom of uranium-235 must impact other uranium-235 atoms to sustain the nuclear chain reaction. The concentration and amount of uranium-235 needed to achieve this is called a 'critical mass'.
Question: What is the term for the amount of uranium-335 needed to sustain a nuclear chain reaction?

Output: unanswerable

Input: Read this: The Paleozoic spanned from roughly 541 to 252 million years ago (Ma) and is subdivided into six geologic periods; from oldest to youngest they are the Cambrian, Ordovician, Silurian, Devonian, Carboniferous and Permian. Geologically, the Paleozoic starts shortly after the breakup of a supercontinent called Pannotia and at the end of a global ice age. Throughout the early Paleozoic, the Earth's landmass was broken up into a substantial number of relatively small continents. Toward the end of the era the continents gathered together into a supercontinent called Pangaea, which included most of the Earth's land area.
Question: How many periods of geology are within the Paleozoic era?

Output: six

Input: Read this: The administration continues to follow the market reform plans of the previous one and indicated that it will diversify Iran's oil-reliant economy. Iran has also developed a biotechnology, nanotechnology, and pharmaceuticals industry. However, nationalized industries such as the bonyads have often been managed badly, making them ineffective and uncompetitive with years. Currently, the government is trying to privatize these industries, and, despite successes, there are still several problems to be overcome, such as the lagging corruption in the public sector and lack of competitiveness. In 2010, Iran was ranked 69, out of 139 nations, in the Global Competitiveness Report.
Question: What is a main goal of Iran's market reform plans?

Output:
diversify Iran's oil-reliant economy