Lecture 3

49 Pages
75 Views
Unlock Document

Department
Philosophy
Course
Philosophy 1200
Professor
Eric Desjardins
Semester
Fall

Description
Welcome to lecture #3! I Review I Beginning of chapter 2: meaning Review: Logical strength I Logical strength: an argument has logical strength to the extent that its premises, if true, support its conclusion. I A feature of whole arguments, not statements I A graded notion I Tip: think of logical strength as “logical flow”. An argument has logical strength to the extent that truth flows from the premises to the conclusion. If you pour truth in the premises (the premises are true), you get truth in the conclusion. Review: Logical strength I Logical strength is independent of the truth of the premises I An argument can have maximum logical strength but false premises I An argument can have false premises but maximum logical strength Review: Logical strength I Logical strength is independent of the truth of the conclusion I An argument can have maximum logical strength but a false conclusion (if its premises are false) I An argument can have a true conclusion but no logical strength Review: Logical strength I Clarification: The truth of the conclusion is not independent of the truth of the premises and logical strength together. Review: Deductive arguments I Deductive arguments are arguments with maximum logical strength Review: Soundness I An argument is sound when 1) it is logically strong and 2) it has true premises I Normally, an argument is good when it is sound: I Its premises are true I They support the conclusion (it has logical strength) I Exception: counterfactual arguments Counterfactual arguments I If Steve Jobs was still alive, the iPhone 5 would have had a universal GSM chip, so it would support Wind’s network. Counterfactual argument I An argument in which the premises are known or assumed to be false by the person making the argument. I The point of such an argument is to demonstrate a fact about some other possible world: in the possible worlds in which Steve Jobs is still alive, the iPhone 5 supports Wind’s network. Example I If you had correctly checked the patient’s file you would have seen that she had recently eaten and not administered anesthetic without pumping her stomach. Had it been the case that you followed proper procedure, the patient would not have died. Example I If you had correctly checked the patient’s file you would have seen that she had recently eaten and not administered anesthetic without pumping her stomach. Had it been the case that you followed proper procedure, the patient would not have died. I If you had set the alarm as I requested, I would not have slept in and gotten fired. It’s your fault if I got fired. Reductio ad absurdum I “Reduction to absurdity” I Absurdity = impossibility I To prove a point by showing that its falsity would have consequences that do not obtain. Reductio ad absurdum I Let’s suppose for a moment that Elvis is still alive. Surely he wouldn’t like all the tacky imitators we see around here. So someone would have stopped the imitators. But no one has, so Elvis must really be dead. Reductio ad absurdum I Let’s suppose for a moment that Elvis is still alive. Surely he wouldn’t like all the tacky imitators we see around here. So someone would have stopped the imitators. But no one has, so Elvis must really be dead. Reductio ad absurdum 1. Elvis is still alive (assumed for reductio) 2. If Elvis is still alive, he doesn’t like tacky imitators 3. If Elvis doesn’t like tacky imitators, someone would stop them 4. Conclusion: Someone would stop imitators The conclusion of this argument is known to be false, but it has excellent logical strength, so we can conclude that (at least) one of its premises is false. Reductio ad absurdum I Suppose he was in Toronto at 8 a.m. Witnesses place him in Vancouver at 6 a.m. local time, the same morning. So he would have to have traveled from Toronto to Vancouver in one hour, which is not possible by any known means of transportation. Therefore, he was not in Toronto. Meaning I For this chapter we depart a little from the textbook. If it’s not in the slides, it’s not on the exam. I In particular, note that sections 2.2.1-2.2.2 of the textbook are not subject to examination Interpretation I Words, sentences, and entire texts are sometimes not easy to interpret. I There are many factors to be aware of, including: I Context I Emphasis I Sentence structure I Function I That is all you need to take home from the “meaning is use” theory discussed in the book Context I “The queen is in a vulnerable position” Context I “The queen is in a vulnerable position” I Said at a chess match Context I “The queen is in a vulnerable position” I Said at a chess match I On the cover of a British magazine Context I “The queen is in a vulnerable position” I Said at a chess match I On the cover of a British magazine I “The president is wrong” Context I “The queen is in a vulnerable position” I Said at a chess match I On the cover of a British magazine I “The president is wrong” I Said out loud in the Whitehouse Context I “The queen is in a vulnerable position” I Said at a chess match I On the cover of a British magazine I “The president is wrong” I Said out loud in the Whitehouse I Said at Loblaws while lo
More Less

Related notes for Philosophy 1200

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit