NOTE: To change the image on this slide, select the picture and delete it. Then click the Pictures icon in the placeholder to insert your own image. INFORMAL LOGIC Chapter 2

Our Expectations, we will be able to:  Demonstrate our understanding of the form & components of philosophical arguments  How arguments are different from other forms of communication  Describe critical thinking skills & habits of mind that support philosophical argument, and use them  Correctly use the terminology of logic (formulating and analyzing arguments)  Identify & explain common fallacies of reasoning  Use philosophical reasoning and critical thinking skills in daily life in various contexts

Informal Logic  Found in everyday contexts: conversations, editorials, political debates, philosophical passages  Informal arguments should be logical, if only to avoid violating the principle of non-contradiction  Arguments are cogent:  Meanings are clear & appropriate  Premises are accepted as true  Premises judged as strong support for conclusion  Definitive support only required in deductive arguments, i.e., criterion of validity

How do we judge the cogency of an argument?  How much strength do the premises have as support for the conclusion?  If an argument is not cogent:  It is likely that an informal fallacy has been committed.

Do you accept this reason for a failed exam?

Dissecting an argument 1.Identify premises and conclusions, including sub- arguments (arguments with arguments) hidden premises 2.Examine the relevance or truth of the premises and the connection between premises & conclusions. Consider the example on pages 44 & 45.

Fallacy: seems cogent but isn’t Examples from the “Fallacy Toolkit”  The fallacy of the Problematic Premise  Accepting as true a premise that is doubtful  We can always ask if we should accept the premises as true  The premise cannot contradict other propositions held as true (principle of non-contradiction)  If the premise asserts “facts” they should be in agreement with own experiences/observations  If premise based on something heard or read, is the source credible?

The Hasty Generalization & the Principle of Charity  Applying the truth of one (or a few) experiences to argue that the truth happens in general.  I had a bad experience with a person who ______________,  Therefore, all people who are _________________ will result in the same bad experience.  When interpreting text, or the argument of another, make a sincere effort to reinterpret in a way that is true (i.e., consistent with) the author’s intent  When one recreates an argument consistent with the author’s intent, the fallacy committed, STRAW MAN

Informal Fallacies A Focus: people or groups, not the issue at hand  Attack on the person (ad hominem)  Attacking the arguer, not the argument  Instead of discussing the issue and the argument being made, one attacks the arguer’s personality “U.S. President G.W. Bush may have had reasons for invading Iraq, but he is nothing other than a nationalistic, simple-minded war-mongerer bent on bullying the world with his powerful military toys. He should not be taken seriously.” If Bush had reasons: look at them carefully and rebutted if not cogent.

Appeal to Tradition  Using the existence of the past practice to justify the continuing of the practice. Father to daughter: “It is our tradition for a bride’s family to provide a large dowry to the groom. I know that you want to argue gender equality is changing all this, but it is our tradition.”  We can recognize a practice as traditional, but we can question it  It is helpful to provide reasons to continue the tradition

Attack on the motive  Attacking the credibility of a person or group on the grounds that the person or group has biases or motives perceived as the real reasons. “Economist Milton Friedman has argued in favour of reducing federal income taxes, but his argument should be discounted. Friedman is a millionaire who would benefit greatly from a reduction in taxes. Also, Friedman has no need for government social programs, which are provided through higher taxes.”  He may have good reasons, other than his personal gain, examine them

Bandwagon / Appeal to popularity  If everyone likes it, you should too!  Appealing to what many, if not most accept. (but majority can be wrong!)  Consider most ads highlighting their product as being the “number 1 selling….”

Straw Man  Misrepresenting another’s argument  Making it “weaker” and therefore easier to “knock down”  Look at page 50