FSU PHI 2100 - REASONING AND CRITICAL THINKING

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REASONING AND CRITICAL THINKING 01 10 2013 The uses of arguments What is an argument A set of sentences one of which is the conclusion others are the premises where the premise supports the conclusion o Premises are given for the purpose of providing reasons or logical support for believing or understanding the conclusion proving the conclusion s truth Why are arguments important If every true sentence were obviously true I am sitting in a chair then there would be no need for paying attention to arguments That is not the case however so arguments are a way of having reasonable beliefs about non obvious matters Some questions that arguments are useful in answering are o Is A true helps solve true or false statements yes or no answer o Why is A true expects different answer than that above Is A true Attempts to convince someone that a sentence is true Justification Normative justification convincing someone in a legitimate way In other words convincing someone that a sentence is true b c there is GOOD reason to think that it is true a reasonable person out to believe it o Not the way the world is but the way it OUGHT to be Normative is what you SHOULD VE done o Compare normative justification with justifications by deceit using misleading information to get what you want lying etc o NORMS for reasoning o 2 kinds of Normative Justifications Impersonal not a specific person should convince any reasonable person mathematical proofs scientifically proven things like H20 etc Personal justifications that only apply to a certain set of people They take the form if you believe A then you should also believe B Why is A true Attempts to account for why something is true Explanations Already grants that A is true so no need for justfications Often we have justified beliefs but we may still be puzzled by them o Ex You loaned a friend headphones and when you get them back you notice teeth marks in the cord No arguments need to convince you that someone chewed the headphones Your SENSES give you all the evidence you need But you will want an argument to explain WHY anyone chewed on the cord in the first place You ask WHY an explanation General Principles and Explanations Given all of our experiences and experiments we are confident that some general principles hold in the world o Ex Gravity genetic theory Many explanations are arguments that are well established general principles law as premises along with the specific details of the situation that is under investigation o More EXs Pg 9 4 5 7 ABSENT 1 15 13 REASONING AND CRITICAL THINKING 01 10 2013 Deep Analysis and Argument Evaluation Reconstructing arguments Often it is up to you to reconstruct an argument based on what someone else has written or said What does reconstruct mean here o Usually arguments are listed in standard form o Why Often ppl go on tangents and even present red herrings when an arguer intentionally distracts you from what is important and throws you off track deceiving you Red herring o People frequently assume more than they say What is a argument called prior to reconstruction that assumes but leaves some of the premises suppressed ENTHYMEMATIC an incomplete syllogism in which one or more premises are unexpressed as their truth is considered to be self evident What is the principle of Charity o Putting the argument in the best light possible o What is a STRAW MAN reconstruction weakening someones argument Argument can easily be pushed over o DON T STRAW MAN BE CHARITABLE o Reconstruct an argument the best that u possibly can Clarifying crucial terms Ambiguity Vagueness It is often necessary to eliminate ambiguity and reduce vagueness before we can give an argument a fair assessment p 109 when a word or phrase has multiple meanings unclear Occurs when it is not clear what counts as an instance of the word There are borderline cases matter of opinion bald example pile of sand example Argument Evaluation Once you have reconstructed an argument it is time to evaluate whether it is good or bad An argument is bad if o 1 A non starter one or more of what the arguer is taking to be the premises are not true example of non starter arguments 1 all squares have four sides 2 all rectangles are squares C all rectangles have four sides why is this a non starter 2 is not true so why is the argument bad Because you shouldn t be convinced of C based on this argument o 2 Circular one or more of the premises are true only if the conclusion is true before the argument or example of circular argument 1 what is written in the bible is true because it is divinely inspired 2 God s existence is affirmed in the bible C God exists why is this argument circular This could not show the conclusion more probable since 1 depends on the conclusion Does this mean the conclusion is false NO Called begging the question circular reasoning o 3 Weak regardless of whether or not the premises are actually true even assuming that they are true does not make the conclusion any more plausible than before the argument Example of a WEAK argument Why is this argument weak 1 Last Tuesday you failed an exam 2 The Tuesday before that you sprained your ankle C Bad things always happen to you on Tuesdays Two Tuesdays out of the entire course of your entire life is a very small portion of the number of Tuesdays you ve lived through Not enough evidence to prove conclusion as true arguments BEST The o An argument is good if its not a non starter circular or weak o Of the good arguments some are still better than others Which are best Deductively sound arguments arguments with true premises What is a valid argument deductively valid An argument is valid if it is impossible for the premise to be true and the conclusion false Ex Of a sound argument 1 All humans are mortal 2 Socarates was a human C Socarates was mortal Why is this sound 1 and 2 are true and the argument is valid it is not possible for the conclusion to be false if the premises are true o look at the form of this argument 1 All H are M 2 S is H c S is M Next BEST Arguments the o though sound arguments are the best there is another type of argument that is also good Cogent argument inductively cogent Inductively strong arguments arguments with true premises than before the argument but not absolutely un doubtable given the premises invalid though conclusion is made more probable Example of a strong argument 1 the lottery tickets you ve purchased account for 75 of the possible outcomes c You will win the


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FSU PHI 2100 - REASONING AND CRITICAL THINKING

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