Objectives • To understand how reason can be used, or misused to justify knowledge claims • Be able to analyse a reasoned argument and evaluate its strengths and weaknesses
Informal Fallacies “A fallacy is any sort of mistake in reasoning or inference; it is a term used to denote anything that causes an argument to go wrong.” (Popkin and Stroll, 1993) Great news mum! I got 80% on my math test. That’s great, but what was the average mark? The average was 95%.
Comprehensive House Insurance except for Acts of God This is an example of a fallacy based upon the incorrect emphasis of the words in a sentence. The fallacy of ‘quoting out of context “Tom is very good at making excuses for not handing in his homework and generally fails at maintaining high standards most of the time.” “Tom is very good ……maintaining high standards most of the time”
Argumentum ad hominem This means an argument against the person. A statement cannot be shown to be false merely because the individual who makes it can be shown to be a person of defective character.
Examples of other fallacies Arguing from authority Arguments which appeal to sentiments Argumentum ad ignorantiam Fallacies of ambiguity Example; water the plant when thoroughly potted Statistical fallacies
Arguments in symbolic form In the 20th century philosophers started to turn their attention to language. Gottlob Frege and Bertrand Russell developed a new type of logic to analyze statements in ordinary language. They both used symbolic terms governed by logical rules to analyze language. An example of this is the truth tables developed by Wittgenstein. Let P = the sky is grey and Q = It is raining If the sentence “The sky is grey and it is raining” is true then both connectives have to be true p q p&q T T T T F F F T F F F F
Liar Paradoxes This sentence is False If this sentence is true then it is false. Whichever way we read it, true or false, it still leads to a contradiction. This is known as a self-referential paradox. These paradoxes have caused serious problems for the logical systems of Leibniz, Frege and Russell (Cyran et al, 2001). http://www.youtube.com/watch?v=ILlvG78ZldQ
Problems of language “Our language can be seen as an ancient city; a maze of little streets and squares, of old and new houses, and of houses with additions from various periods; and this surrounded by a multitude of new boroughs with straight regular streets and uniform houses.” (Wittgenstein, 1953)
Logical choices Pascal’ wager You can choose to believe in God; you can choose not to. What are you going do? If you believe in God and she/he exists you can look forward to an eternity of heavenly bliss. If he/she does not exist then maybe you have wasted a few Sundays and have been a little inconvenienced, but nothing really disastrous has occurred. However, if you don’t believe in God and he/she does exist then it is an eternity of damnation. Therefore, any prudent person should believe in God to be on the safe side. (Adapted from Priest (2000))
Epistemology Justifying knowledge claims Sense perception Logic Intuition Self awareness Memory Authority Consensus gentium Revelation Faith
Justifying knowledgeclaims In a court of law a witness claims that the accused committed the crime because she said she saw him do it. What knowledge justifications is her testimony based on?
Justification of Knowledge Claims A passionate argument can convince many people. The masses can be swept along with a tide of emotion. Why must these types of arguments be scrutinized in the cold light of day? McCarthyism during the 1950s in the United States of America Can you think of any other examples?
In the context of the work covered in this topic on reason discuss the following. In what ways can the person presenting an argument and the context in which it is made influence its acceptance or rejection? In everyday discourse, the ‘rational’ choice is usually equated with the ‘best’ choice. Does this conjunction hold in all social contexts? What did Pascal mean by the comment that ‘The last function of reason is to recognize that there are an infinity of things which surpass it’? To what things does he refer?
Reading The Crucible by Arthur Miller Animal Farm by George Orwell Candide by Voltaire The Remains of the Day by Kazuo Ishiguro The Quiet American by Graham Greene
References Cyan D., Shatil S. and Mayblin B. (2001) Introducing Logic. (Cambridge; Icon books) Popkin R. H. and Stroll A. (1993) Philosophy. (Oxford: Elsevier Science). Priest G. (2000) logic: A Very Short Introduction. (Oxford; Oxford university Press). Wittgenstein L. (1953) Philosophical investigations. (Oxford: Blackwell).