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The " hard problem of consciousness " is the problem of explaining why and how we have qualia Colin McGinn , and Ned Block and cognitive neuroscientists such as Francisco Varela , Giulio Tononi , and Christof Koch .
 Colin McGinn, Ned Block, Francisco Varela, Giulio Tononi, Christof Koch
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: media, plant, vehicle, astronomical object, time, disease, animal, location, person, organization, mythical figure, food, biology, geographical phenomenon, instrument, event 
Text: {0} 
Answer:
 Colin McGinn, Ned Block, Francisco Varela, Giulio Tononi, Christof Koch