Checking for Validity with Diagrams

One way to check validity of a claim is using a diagram.  The way you create the validity checking diagram is you choose a claim. My example claim is:

All true sports fans own jerseys of their favorite players. Matt has a Patrick Marleau San Jose Sharks Jersey. So Matt is a true sports fan.

To create the Diagram, you first you see which statements follow under the others. So "all true sports fans" would go under the statement of "fans who own sports jerseys".  So "all true sports fans would be put in a small circle.  Then around that circle you would draw a larger circle and write "Fans who own sports jerseys" inside it.  The in same circle you would "a. Matt" to show that Matt is a both a true sports fan and he is a fan who owns a jersey. 

After making your diagram, draw the areas to represent the premises as true while trying to represent the conclusion as false.  If you can, then the argument is invalid. If there is no way to represent the premises as true and the conclusion as false, then the argument is valid.

So going back to our example we conclude it is false because the claim says matt has a sports jersey but it doesn't mean it is his so we can't know for sure if he is a true sports fan or not.

Understanding General Claims

I think so far in the class, the topic that was least clear to be was the idea of vague and general claims.  I never really knew what parameters they were judged by or how I would know how to identifiy them.  But in chapter 8, Epstein introduced us again to the idea of general claims.  Epstein describes general claims as, “claims that assert something in a general way about all or a part of a collection”. He explained that for us to be able to understand if the general claims made are valid, we first have to understand a few key words used in general claims. These words are:

-All means “Every single one, no exception. ”Sometimes all is meant as “Every single one, and there is at least one.” Which reading is best may depend on the argument.

-Some means “At least one”. Sometimes some is meant as “At least one, but not all”. Which reading is best may depend on the argument.

-No means “not even one” “every single one is not”.

-Only  “Only S and P” means “All P and S”.

To put this idea in a real life situations, I made an examples of my own:

-All students study.

(This is a weak argument because not all students are motivated enough to study so this claim is false).

-Some teachers have good teaching methods.

(This argument is also weak because there isn’t a very good way to prove that only “some” teacher have good teaching methods because different teaching methods are good for different people.)

-No cats bark.

(Even though this is a true statement it is a weak claim because this is already a well-known facts and would not be very useful in any argument.)

-Only alcoholics like the taste of alcohol.

(This is a weak claim because there is a good possibilities that there is an alcoholic out there who doesn’t like the taste of some kind of alcohol or there is a non-alcohalic who likes the taste of an alcohol.)

The Usefulness of Assignment #1: Critical Thinking in News and Politics

The reason I found the first group assignment we had, assignment #1: Critical Thinking in News and Politics, very useful was because this paper allowed me to see the ideas we were learning in the class used in a way other than blogging and it also let me see topics that I had learned and perceived in one way in other people’s point of views.

            When doing our weekly posts I always explain a topic in a way that makes sense to me and then think on an example off the topic of my head, using the easiest example I can think of. But with this assignment it made me force myself to understand a topic, infuse it into a topic we had already chosen (for this assignment we had to do it on an article and I never tried this idea before), and write it so it would work fit in to a paper that was being composed of four other people’s ideas and points of view.  I also liked this assignment because when I read our final paper that was composed of all our ideas and view on particular parts of the assignment it made me realize how many different ways these topics could be used in a written assignment.

            An example of this is when I read one of my group-mates individual responses and compared it to my own. In theirs they described that after using all the ideas we learned, they decided the writer of the article we read used very weak claims and arguments and after reading it, it changed their perspective negatively against the view point given.  But in my personal response, I explained completely different reasons of why I thought the articles argument was weak and even though I thought the authors claims were bad my perspective of the issue still didn’t change. So It was cool to see our two different ideas and outcomes from this assignment.  

Refuting Arguemnts Directly versus Indirectly (Chapter 7)

 In Chapter 7, I learned how to refute arguments both directly and indirectly.

First Epstein explained how to refute and argument directly by explaining three direct ways of refuting and argument:

Direct ways of refuting an argument:

-show that at least one of the premises is dubious

-show that the argument isn’t valid or strong

-show that the conclusion is false

Knowing how to refute and argument is useful because after seeing all the ways we can refute an argument may lead us to see that an argument is unrepairable.

To refute an argument indirectly means that you may not be able to find one single premise that is false or dubious but you notice that the premises overall to the conclusion may be false or dubious. A way to refute indirectly is using the idea of reducing the absurd, meaning, to reduce to the absurd is to show that at least one of the several claims is false or dubious, or collectively they are unacceptable, by drawing a false or unwanted conclusion from them. One thing to remember when refuting indirectly is that you have to be sure the argument you use to refute the dubious and false conclusion argument is strong or valid and that it doesn’t use any other dubious claims or your refutation will be as useless as the argument you are refuting.

Reasoning with “or” Claims

In chapter 6, Epstein describes how we can often determine that an argument is valid or weak by if we look at what role the compound claim plays in it.  There are two different main sequences for compound claim arguments. The first is, sometimes called the disjunctive syllogism that consists of A or B, not A, So B is valid or A or B + not A= B valid. An example is:

“Either my roommate took my book on mistake (A) or I lost it (B). My roommate said she doesn’t have my book (not A), so I must have lost it (B=valid).”

This form can also be extended to more claims such as A or B or C, not A, not B, therefore C.

Another type of sequence for compound claim arguments is: where you can only reduce the possibilities, not exclude all but one. Meaning: A or B or C or D, not A. not C, therefore B or D. An example Epstein gave is:

Either all criminals should be locked up forever (A), or we should put more money into rehabilitating criminals (B), or we should accept that our streets will never be safe (C), or we should have some system for monitoring ex-convicts (D). We can’t lock up criminals forever (A), because it is too expensive. We definitely won’t except our streets will never be safe (C). So either we should put more money in rehabilitating criminals (B), or we should have some system for monitoring ex-convicts (D).

Coumpound Claims and the Contradictory of a Claim

In Chapter 6 of the Epstein text, I learned what a compound claim is and what the contradictory of a claim is.

            To understand what a compound claim is, you first need to know the definition.  Epstein defines compound claims as: A compound claim is one composed of other claims, but which has to be view as just one claim. An example of a compound claim is: “I’ll return your hairbrush or ill buy you a new one.” In this claim, he promises to do one or the other, either return the hair brush or buy a new one, not do both which makes it just one claim.

            To understand the idea of contradictory claims, you first need to know what “contradictory of a claim” means.  Epstein described contradictory of claims as: the contradictory of a claim is one that has the opposite truth-value in all possible circumstances.  Sometimes a contradictory is called the negation of a claim. An example of a contradictory claim is:

Claim: Daisy is barking.

Contradictory: Daisy is not barking.

            To be able to connect the two ideas I have learned this chapter, Epstein described "the contradictory of an or claims", which means that A or B has contradictory not A and Not B. So the contradictory to my first example would be. “I will not return your hairbrush and I will not buy you a new one”.

The Principle of Rational Discussion

 So far in the semester we have discussed the idea of violating the principle of rational discussion but we have never discussed the idea rational discussion. Epstein described rational discussion as:

The Principle of Rational Discussion

We assume that the other person who is discussing with us or whose arguments we are reading:

1.    Knows about the subject under discussion.

2.    Is able and winning to reason well.

3.    Is not lying.

So the main thing you consider when evaluating a discussion a rational or irrational is if the person actually know what they are talking about, if their argument is in reason, and also if you think they are telling the truth. One other idea Epstein mentioned was the idea of irrationality. He described it as:

The mark of irrationality:

If you recognize that an argument is good, then it is irrational not to accept the conclusion. 

So when it comes to rational discussion, also remember that you need to be thinking rationally, like the idea he gave above that if argument is good than that most likely means the conclusion and premises are good too.

Concept of Repairing Arguments

In chapter 5, Epstein gives us a guide to repaing arguments which is provided below:

Given an (implicit) argument that is apparently defective, we are justified in adding a premise or conclusion if it satisfies all three of the following:
1.  the argument becomes stronger or valid
2.  the premise is plausible and would seem plausible to the other person
3.  the premise is more plausible than the conclusion
If the argument is  then valid or strong, we may delete a premise if doing so does not make the argument worse.

If we go back to Chapter 11, Epstein describes what it means to violate the principle of rational discussion.  He describes how sometimes it seems the other person does not understand what is invloved in rational discussion or is intending to mislead and sometimes there is not even an argument. Some ways one can violate the principle of rational discussion is to beg the principle, using a strawman, shifting the burden of proof, irrelevant premises, slanters (concealing claims that are dubious by misuse of language), and ridicule (making someone or something the butt of a joke in order to convince). Now let put both ideas to work in an example.

Example:  Mrs. Geary is  my professor.  Therefore Mrs. Geary is a good teacher.
Analysis: "Mrs. Geary is good at explaining topics in a way that everyone can related to and remember" is the only premise that will make the argument valid or strong. So I added it. Than, since that is true and the argument doesnt violate the principle of rational discussion, the argument is now good.