PHLA10 Reason and Truth Exercise 1

Transcription

1 Y e P a g e 1 Exercise 1 Pg When is an idea or statement valid? (trick question) A statement or an idea cannot be valid; they can only be true or false. Being valid or invalid are properties of arguments, meaning that only they can be valid or invalid. Arguments can still be valid even if the premises or conclusions are obviously untrue, or if the premises and conclusion are all false. 3. Invent an example of a valid argument that has false premises and a true conclusion. Invent an example of an invalid argument that has true premises and a true conclusion. Valid argument: All dogs can fly. Jack is a dog. So Jack can fly. Invalid argument: If the dog is running, then the dog has four legs. The dog has four legs. The dog is running. 5. Which of the following argument forms is valid? Which is invalid? For each of the invalid ones, construct an example of an argument with that form in which the premises are true and the conclusion false: (a) Valid (b) Invalid If Sam lives in Wisconsin, then Sam lives in the USA Sam lives in the USA Sam lives in Wisconsin Converse (c) Invalid If Sam lives in Wisconsin, then Sam lives in the USA Sam doesn t live in Wisconsin Sam doesn t live in the USA Contrapositive

2 Y e P a g e 2 (d) Valid 7. What does it mean to say that an argument is circular, that it begs the question? Construct an example of an argument of this type different from the ones presented in this chapter. When an argument is circular or that it begs the question, it does not give you a good reason to accept the conclusion even if the premises and conclusion are true. If the premise was not accepted, then the conclusion would not be accepted either. The Earth is a planet. Therefore, the Earth is a planet. Pg What is the difference between deductive validity and inductive strength? Deductive validity is either valid or invalid, there is no middle ground. An argument of this type is based on whether the premises are true, which in turn indicate whether the conclusion is true. Furthermore, deductive valid arguments cannot introduce new information in the conclusion that wasn t already there, while inductive strength arguments can conclude on things that are beyond what was in the premises. Inductive strength can either be stronger or weaker depending on the sample size and the unbiasedness of it. 2. What is the difference between induction and abduction? Induction is taking a description of a sample and extending it to things outside the sample, for example sending out polls to figure out what the country s preference of political parties are Abduction is reaching the best explanation possible based on evidence and reasoning. 3. What factors affect how strong an inductive argument is? The factors affecting how strong an inductive are the sample size and the unbiasedness of the sample. Exercise 2 1. Here's a little logical puzzle: you are in a strange land where everyone is either a knight or a knave. Knights always tell the truth; knaves always lie. You meet two of them, A and B. A says "we are both knaves". What are A and B? Prove it. If A is right, then he has to be lying because he said that he is a knave as well. A cannot be a knight because they cannot both be knaves or that would make his statement true. As thus, B must be a knight. A is a knave and B is a knight. 2. What are the four main characteristics of God as Aquinas understood it?

3 Y e P a g e 3 Aquinas characteristics of God are that he is a personal God, omnipotent (all-powerful), omniscient (allknowing) and omni-benevolent (all-good). Aquinas concept of God is also known as PKG. 3. What is the primary difference between the conception of motion that Aquinas accepted and Newton's conception of motion? Aquinas conception of motion was that there needed to be an outside force acting on it for it to be moving and that that force had to be kept for the object to continue being in motion. Newton s law of motion says that an object s acceleration will not change unless acted on by a force so it could remain in uniform motion. 4. Explain why the "Birthday Fallacy" is a fallacy. The Birthday Fallacy is considered to be a fallacy because the second premise does not necessarily follow the first. While the first premise, every person has a birthday a day on which he or she was born, is true, the second premise, there is a single day that is everybody s birthday, does not mean that everybody was born on the same day. The fact that there was a cause for the beginning of events does not mean that it was the same cause for all the events. 5. What is the valid deductive logical form of a reductio ad absurdum argument? If P is false, then A is true. A is false. P is true. 6. What is the difference between necessity and contingency? Necessity means that an object exists in all possible worlds while contingency means that an object doesn t exist in all possible worlds. 7. What is a "necessary being"? Explain in terms of possible worlds. A necessary being is something that exists in all possible worlds. It does not depend on anything for its existence at any time from the past to the present to the future. 8. Why does Sober say that certainty is in the subjective realm while necessity is objective? Certainty is about how sure the person is of themselves about a particular statement and is as such subjective. However, necessity has nothing to do with what a person thinks or believes and is therefore objective.

4 Y e P a g e 4 Exercise 3 1. Explain the structure of arguments from analogy. Arguments of this sort compare two things together, the analog and the target. There must be similarities between the two for the analogy to be good. Features from the analog are compared to the target. For example, the intricate design of the universe compared to one of a watch. 2. Why might the argument from design be a very weak inductive argument? An inductive argument relies on sample size and extrapolating data from it to the broader view. In the argument that the universe was created by an intelligent being says that that data must have been seen in other universes, and then applied to ours. 3. What is the difference between theistic evolutionism and creationism according to Sober? Theistic evolutionism states that it is God who set the evolutionary process in motion. Creationism denies that evolution is able to give rise to new species and that God plays a direct role in shaping organisms. 4. What is the 2nd Law of Thermodynamics? A closed system will move from states of greater order to states of lesser order. 5. Roughly explain how natural selection works. Amongst a population, mutations will arise in the genes at random which may or may not be advantageous. This affects the fitness of the organism. If it is advantageous and allows the organism to better survive, its chances of reproduction improve and these genes are thus passed on to the next generation. 6. An important concept in the theory of evolution is that of fitness. What is fitness? Fitness is an organism s ability to survive and reproduce. 7. Give a new example of a correlation with a common cause. A dog starts to bark and then a few minutes later the doorbell rings. When the dog doesn t bark the doorbell doesn t ring. There may be a correlation between when the dog barks and when the doorbell rings.

5 Y e P a g e 5 8. What is "the tree of life"? All living things are related to each other, being descendent of a common ancestor. Exercise 4 1. Why does Sober say that proving existence from a concept or definition is "very surprising"? A definition of concept only explains what characteristics something would have if it existed, not that it does in fact exist. 2. What is the difference between conceivability and possibility? Possibility is an objective point of view. It does not matter whether people believe it or think it to be true. Conceivability is a subjective point of view. 3. Why is the "perfect island" a problem for the ontological argument? The perfect island is showing that the ontological argument is wrong through reductio ad absurdum. By replacing God with P-island and being for island, Gaunilo tries to deduce that: A P-island is by definition the greatest possible island. An island that fails to exist in the actual world (while existing in other possible worlds) is less perfect than an island that exists in all possible worlds. Hence, a P-island exists necessarily. The existence of a perfect island cannot be determined a priori and as such, neither can the existence of God through the ontological argument. 4. Try to give three clear examples of analytic truths and three of synthetic truths Analytic truths are a priori statements and are definitions or its deductive consequences. All monkeys are animals. All boats are able to float. All apples are fruits. Synthetic truths are a posterior statements and does not follow from definition but from experience. The orbit of the earth is elliptical. Men are more likely to be colour blind than women. The shoulder blades of a cat sit in muscle only.

6 Y e P a g e 6 5. Are all falsifiable statements false? Explain your answer. A falsifiable statement does not mean that it is false. Such a statement means that it must be able to prove that some observations are not true. It can also be refuted through valid deductive arguments if the observations are false. 6. What is the difference bewteen prudential and evidential reasons for belief? A prudential reason is when someone believes for their self-interest. Evidential reason is when someone believes because there are facts that can back up the claim. 7. Consider this situation: you are rolling a single die and you get paid $1.20 if you roll either a 1, 2, 3 or 4 but you have to pay $1.50 if you roll a 5 or 6. What is the expected utility of this game? [(Payoff/utility) x (Chance)] [(Risk) x (Chance)] = (Expected Utility) (1.20 x 2/3) (1.50 x 1/3) = 0.30 The expected utility of this game is $ Try to explain Clifford's objection against Pascal's (and James's) argument. Clifford says that people should not believe things when there is insufficient evidence to support them, His argument is consequentialist, as he is saying that it is wrong to perform this action because it has bad consequences, such as regressing into barbaric times and losing the will to test and inquire. Exercise 9 1. What is the difference between dualism and materialism? Dualism states that the world is composed of physical things (such as the brain) and mental things (such as the mind). Materialism says that there are only physical things in the world and not mental things; to materialism, the mind and the brain is one. 2. What is Leibniz's Law? What is it good for? Leibniz s Law states that if X = Y then any property of X is a property of Y and vice versa. Likewise, even if one property is amiss, then you can prove that the two objects are different. This Law defends the theory of dualism saying that the mind is immortal while the brain is not.

7 Y e P a g e 7 3. Explain what is wrong (according to Sober) with the first Cartesian argument for dualism. Leibniz s Law has holes. If someone were to have a double identity, people could believe that there are differences between what they believe are two people. However in this case, the mistake is that we think a property of the observers is a property of the person with the double identity. As such, if Descartes can doubt that he has a body but not a mind does not show a difference between the two. 4. What is the second Cartesian argument for dualism? This argument says that there is a difference between the mind and brain because the brain has spatial properties while the mind does not. How would you define the mind as having spatial properties though? 5. What is analogical argument which supports the claim that we have knowledge of the mental states of other people? In my case, I notice that I produce behaviour B, I usually am in the mental state M. I observe that other individuals O are now producing behaviour B. So, O are in the mental state M. 6. What is the circularity (Sober calls it "incompleteness") problem facing logical behaviourism? If someone believes it is raining outside, they will take an umbrella when they go outside. However, what if that someone wants to get wet from the rain? Mental states depend on each other. 7. What is a "dispositional analysis" of some concept? Give a new example. The analysis explains a certain behaviour of something when it is placed in a certain situation. 8. What does Sober mean by saying that there is a "physical basis" for any disposition? The basis is the internal mechanisms of something which causes it to behave in a certain way. Exercise 6 1. Try to explain Sigmund Freud's explanation for why people believe in God.

8 Y e P a g e 8 Freud said that people believe in God for the psychological benefits. To make sense of the universe, instead of saying that it is impersonal to us, we make it seem so that it has an interest in humans. 2. Outline the argument against the existence of God based on the presence of evil in the world. (1) If God exists, then he is PKG. (2) If God is PKG, then there would be no evil (If God is omniscient, he knows that there is evil. If God is omni-benevolent, he detests evil. If God is omni-potent, he can rid the evil. God is omniscient, omni-benevolent, omni-potent.) (3) There is evil. (4) Thus God does not exist. 3. Explain the distinction between "theodicy" and "defense" in the philosophy of religion. Theodicy rejects the second premise and accepts the first and third one. Just because God is PKG does not mean there is no evil in the world. Defense rejects the first premise. 4. Is the argument from evil against the existence of God a deductively valid argument? Why or why not. The argument is deductively valid since the form can be used for other arguments. 5. What is "soul improving evil"? Soul improving evil help us become better people as we go through hardship and strengthens our character. 6. Outline the "free will defense" against the problem of evil? God made humans free, meaning it is up to humans to decide whether they do good or evil. However, human decide to do evil. 7. Even if there are soul improving evils and even if some evil is the result of the free will of creatures other than God, does that show the argument from evil fails?

9 Y e P a g e 9 No, because God could have made it that humans could always freely choose good. Free will does not equate goodness. People could have the free choice of doing good. God is after all a free being who does good. 8. What is "natural evil"? Natural evil are evils that do not result from any kind of free will, such as earthquakes or tornadoes. Exercise 6 1. What is the difference between "know how knowledge" and "object knowledge"? Know how knowledge is when the subject s behaviour knows what to do according to certain principles and having certain abilities. Object knowledge requires that the subject directly knows the object. 2. Give some new (not from Sober) examples of necessary and sufficient conditions? Necessary condition: If and only if (1) it has a screen, (2) it has a keyboard, and (3) it has a central processing unit, for any object, the object is a computer. Sufficient condition: An object is a computer if and only if (1) it has a screen, (2) it has a keyboard, and (3) it has a central processing unit. 3. Outline the three conditions that make up the JTB theory of knowledge. The theory says that a subject knows a proposition if and only if: 1. The subject believes that proposition 2. The proposition is true 3. The subject is justified in believing the proposition. 4. Try to think up your own counterexample to the JTB theory (an example that is of the same kind as Sober produces). A person s dog has always been very mild and gentle, so they know that it will knows and believes that it will not bite any strangers. However, that day, the dog got stung by a bee as a stranger was passing by and startled the dog, causing it to bite a stranger. 5. What does Sober mean by the philosophical term "skepticism"?

10 Y e P a g e 10 Skepticism is the conclusion that we do not know anything. Knowledge means that it is impossible for it to be wrong and is known through a posteriori. However, that relies on experiences which rely on sense which can very easily be deceived. 6. What is the difference between the "axioms" and the "theorems" of a theory (such as for example geometry)? Axioms are self-evident, meaning they cannot be false and are absolutely certain. Theorems follow the axioms on pure logic. 7. Outline the core idea of the foundationalist theory of knowledge. Foundationalism says that there is a foundation of beliefs which are solid and true, then superstructural beliefs which are also knowledge because they are resting on the solid foundation. 8. How does Descartes's "method of doubt" discover the foundations of knowledge? The method of doubt asks if there is any doubt at all for any proposition that can be thought of. If it s possible to doubt a proposition, it isn t foundational. If it isn t possible to doubt it, the belief is foundational. However, it does not mean that the belief is false, just not absolutely certain.