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Chapter 11: Argument Mapping

Chapter 10: INDUCTIVE REASONING

    Chapter 10: INDUCTIVE REASONING •      93% of Chinese have lactose intolerance. Lee is Chinese. Lee has lactose intolerance. •      It has never snowed in Palpa in the last 50 years. It is not going to snow in Palpa this year. •      Hari is a sous-chef. Sous-chefs generally have good kitchen skills So, Hari can probably cook well. •      These arguments are of course not valid.   Lee   might be among the   7%   of Chinese who can digest lactose. Snow might fall in   Palpa   this winter due to unusual changes in global weather. But despite the fact that the arguments are invalid, their conclusions are more likely to be true than false given the information in the premises. If the   premises are indeed true , it would be rational for us to be highly confident of the conclusion, even if we are not completely certain of their truth.   •      In other words, it is...

Chapter 9: Valid and Sound Arguments

    Chapter 9: Valid and Sound Arguments 1.     Validity and Soundness ·         Validity   is the most important concept in critical thinking. A valid argument is one where the conclusion follows logically from the premises. But what does it mean? Here is the official definition: An argument is valid if and only if there is no logically possible situation in which the premises are true and the conclusion is false. ·         Whenever we have a valid argument,   if the premises are all true , then   the conclusion must also be true . What this implies is that if you use only valid arguments in your reasoning, as long as you start with true premises, you will never end up with a false conclusion. Here is an example of a valid argument: Maya is 20 years old Maya is more than 10 years old. ·         The validity of the argument can be determined without knowing whethe...