Link-Tested, Keanu-Approved

Here's a trio of links. The first one is a guide to reading philosophy that might help you if you're having trouble understanding the assigned readings.

Jim Pryor's Guide to Reading Philosophy

The next two relate to epistemology and skepticism. The first is about the philosophical implications of the movie The Matrix. If Neo read it, he'd say "whoa."

The Matrix: Dream Skepticism

The last link is an interesting take on skeptical scenarios (or what our textbook fancily calls universal belief falsifiers). Most of us think it's pretty unlikely that we're in a computer simulation like the Matrix. After all, these skeptical scenarios seem so weird. But Nick Bostrom provides some compelling reasons to think that these scenarios may be highly probable, after all.

What's the Probability that We're Living in the Matrix?

(A more advanced version of Bostrom's argument is available here.) By the way, if you have any links you think I or others in class might find interesting, let me know. And feel free to comment on any of these posts.

Review: Soundness

DEFINED: A deductive argument is sound when:
(1) the argument is valid; and
(2) all the premises are true.

WHAT IT MEANS: This is the gold standard—as good as it gets for a deductive argument. Sound deductive arguments are PERFECT. From the start, a sound argument has to be valid. But on top of it, each premise must also be true.

So to test for soundness, we first do our validity test. We do the imagine-a-world test. If the arg fails this test, then it's invalid, and automatically unsound.

If it passes the validity test, then we need to check the actual truth of the premises. So we forget about the imaginary world, and come back to the real world. Are all of the premises actually true in the real world, or is one or more false or questionable (opinionated)? If they're all true, then the argument is sound. If one or more is false or questionable, then the argument is unsound.

An argument is unsound if it is not sound. (duh) But remember, it’s easy for an argument to be unsound. Only one of many things has to go wrong for an argument to be unsound. One false premise, and it’s unsound. One false move in an argument that makes it invalid, and it’s unsound. Any deductive argument that isn't PERFECT is unsound.

Review: Invalidity

DEFINITION: A deductive argument is invalid when the truth of the premises does NOT guarantee the truth of the conclusion.

WHAT IT MEANS: If an argument isn’t valid, it is invalid. This means that you can’t draw the conclusion from the premises – they don’t naturally follow. Invalid arguments do not preserve truth.

EXAMPLES:
1) All humans are mammals.
All whales are mammals.
All humans are whales.

2) If it snows, then it’s below 32 degrees.
It doesn’t snow.
It’s not below 32 degrees.

3) All humans are mammals.
All BCC students are mammals.
All BCC students are humans.

4) Either Yao is tall or Spud is short.
Yao is tall.
Spud is short.

Even though arguments 3 and 4 have all true premises and a true conclusion, they are still invalid, because their form is bad. Argument 3 has the same exact structure as argument 1—a bad structure (it doesn’t preserve truth).

Even though in the real world the premises and conclusion of argument 3 are true, we can imagine a world in which all the premises of argument 3 are true, yet the conclusion is false. For instance, imagine that BCC starts letting whales take classes. The second premise would still be true, but the conclusion would then be false.

The same for argument 4: even though Spud is short (Spud Webb is around 5 feet tall), this argument doesn’t guarantee this. The structure is bad (it’s either this or that; it’s this; therefore, it’s that, too.). We can imagine a world in which Yao is tall, the first premise is true, and yet Spud is tall, too.

Review: Validity

Here's a review of the tricky term "valid" as it refers to deductive arguments:

DEFINED: A deductive argument is valid when the truth of the premises guarantees the truth of the conclusion.

WHAT IT MEANS: Validity focuses on the form or structure of the argument. If an argument is valid, then it has good form – truth preserving form.

Basically, if we assume that all the premises are true, then the conclusion must also be true for an argument to be valid. Notice we are only assuming the truth of the premises, not checking to see whether they are actually true. Again, this makes sense, because we’re truth-preservers: if the premises were true, the conclusion that follows would have to be true.

EXAMPLES:
(1) All humans are mammals.
All mammals have hair.
All humans have hair.

(2) If it snows, then it’s below 32 degrees.
It snows.
It’s below 32 degrees.

(3) All humans are mammals.
All mammals have wings.
All humans have wings.

(4) Either Yao is tall or Spud is tall.
Yao is not tall.
Therefore, Spud is tall.

Even though arguments 3 and 4 are ultimately bad, they are still valid—their form is good. The second premise of argument 3 is false—not all mammals have wings—but it has the same exact structure of argument 1—a valid structure. Same with argument 4: the second premise is false (Yao Ming is about 7 feet tall), but the structure is good (it’s either this or that; it’s not this; therefore, it’s that).

To evaluate validity, then, assume that all the premises are true. Imagine a world in which all the premises are true. In that world, MUST the conclusion also be true? Or can you imagine a scenario in that world in which the premises are true, but the conclusion is still false? If you can imagine this situation, then the argument is not valid. If you cannot, then the argument is truth-preserving (inputting truths guarantees a true output), and thus valid.

IMPORTANT: Individual statements are true or false. Arguments are valid or invalid.

Reading Response #1

Reading Response #1 is due at the beginning of class on Wednesday, September 19th if you're in the Holy Cross class, or Thursday, September 20th if you're in the Mt. Laurel morning class. In a 250- to 500-word essay response, answer the following question:

What does Descartes say he cannot be certain of? What does Descartes say he can be certain of? What are his arguments for this? Do you agree with Descartes? Why or why not?

The response is based on the Descartes reading from pages 58-71 of the textbook.

More on Understanding Args

Some students asked for more arguments that they could practice converting into a formal premise/conclusion format, so here they are. These are a little easier than the ones we did in class--more like what you'll see on the quiz. To check your answers, email me or write your answers in a comment to this post, and I'll let you know how you did.

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1. Fairdale will win the championship because they have the best team.

2. Since the housing market is depressed and interest rates are low, it's a good time to buy a home.

3. China is guilty of extreme human rights abuses. Further, they refuse to implement democratic reforms. Thus, the U.S. should refuse to deal with the present Chinese government.

4. The revocation of the 55 mph speed limit has resulted in an increased number of auto fatalities. So we must alleviate this problem with stricter speed limit enforcement.

5. We may infer that the U. S. military is both capable and competent from the results of the Persian Gulf War.

6. Scientific discoveries are continually debunking religious myths. Further, science provides the only hope for solving the many problems faced by humankind. Hence, science provides a more accurate view of human life than does religion.

7. Jesse is one year old. Most one-year-olds can walk. It follows that Jesse can walk.

8. I deserve a raise. After all, I'm very good at my job.

9. We must resist all effort to allow the government to censor entertainment. Freedom of speech and expressions are essential to a democratic form of government. As soon as we allow some censorship, it won't be long before censorship will be used to silence the opinions critical of the government. The next thing we know, we will have no more freedom than the Germans did under Hitler.

10. Maebe is probably sick today, since she did not show up for work. And she has never missed work unless she was sick.

11. The United States, as the most powerful nation in the world, has a moral obligation to give assistance to people who are subjected to inhumane treatment. The ethnic Albanians were being persecuted in Kosovo. This is why it was proper for the U.S. to become involved in the air campaign against Kosovo.

12. The last person we hired from Bayview Tech turned out to be a bad employee, so I'm not willing to hire anybody else from that school again.

13. Since love and fear can hardly exist together, if we must choose between them, it is far safer to be feared than loved. For of men it may generally be affirmed that they are thankless, fickle, false, studious to avoid danger, greedy of gain, devoted to you while you confer benefits upon them, and ready, while the need is remote, to shed their blood, and sacrifice their property, their lives, and their children for you. But, when danger comes near they turn against you. (from Machiavelli's The Prince)

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Hat tip: I took examples 1-8 (with some revisions) from Beth Rosdatter's website, and examples 9-13 (with some revisions) from Jon Young's website.

Holy Cross Class Relocation

To the Wednesday night Holy Cross class (Tuesday/Thursday morning students can ignore this):

I just found out that BCC classes cannot meet at Holy Cross on Wednesday, September 19th due to Back-to-School Night. Instead, our class is going to be held at Room 121 of the Willingboro Center. We're only going to be there for the one night.

The Willingboro Center is located at 300 Willingboro Parkway in Willingboro, NJ 08046. Their number is 609-877-4520. Directions and a map are below.

Directions
From the North
Take U.S. Route 130 south until you see the Willingboro Town Center on your left (Merck Medco Facility and BCC building). Proceed to the next jughandle and use it to make a left turn across Route 130. Make the first left into the Willingboro Town Center and follow the signs to the BCC facility.

From the South (Delran, Cinnaminson, Palmyra, etc.)
Take U.S. Route 130 north to the Willingboro Town Center. Turn right into the Center and follow the signs to the BCC facility.

From Mt. Holly, Lumberton & Hainesport
Take Beverly-Rancocas Road to U.S. Route 130. Turn tight into Route 130 north until you reach the Willingboro Town Center. Turn right into the Center and follow the signs to the BCC facility.

Click on the map below to enlarge it:

My Prerogative

Nothing says 'philosophy as a worldview' like 1989 Bobby Brown:

Bobby Brown - My Prerogative