What Carl Sagan has to say about science and truth

 When I started reading The Demon-Haunted World: Science as a Candle in the Dark by Carl Sagan, I did not really know what to expect. Sagan invites the reader to be critical and skeptical of things we read, see, or hear about. He wants us to distinguish between what is "valid science" and "pseudoscience." As a science major, I have always accepted science as factual information that is true until proven otherwise since I was young. In my current biology class, we are studying about paleontology which involves looking at fossil records of animals to infer relationships between extinct and living species. This class gets me wondering about how I can fully trust and appreciate what I am learning since it is all based on the evidence we have right now which will probably change in the next couple of years when a new discovery is made. Sagan says that we have to be skeptical of what we read, and I try to do that when I am reading science. It is interesting to see if science and religion would receive the same weight of skepticism since Sagan believes that there is a lot in real science that will get us closer to the truth (page 4). But how much importance can we place on science for explaining disease and death for instance for someone who is very religious and spiritual and does not believe in scientific discovers. How could you explain the truth for that person? 

 In the chapter about Hallucinations, there is a line on page 105 that says: "...much of culture is hallucination," and that "the whole intent and function of ritual appears to be...[a] group wish to hallucinate reality." I looked up the definition of the word hallucinate. According to the OED, hallucinate is "to be deceived, to suffer illusions, entertain false notions, blunder, mistake." I looked up the etymology and it says that it means "to wander in mind, talk idly, prate." I am wondering what the quote above means after looking up the definitions of hallucination as a verb and a noun. I feel that it is extreme to suggest that people's rituals are a way to "entertain false notions" about reality.