PHIL M9 Chapter 1.1 to 1.4

Premise Indicators

terms that usually signals a particular reason or piece of evidence to support the conclusion.

Conclusion Indicators

Words or phrases that can help you identify which statement in an argument is the conclusion.

Euthanasia should be considered only in extreme cases. We can conclude this for the reason that some people in even the deepest coma states occasionally regain consciousness. This conclusion must also be true since widespread euthanasia would create a model of murder for convenience. And finally, the conclusion follows inasmuch as the costs of keeping a person alive in a vegetative state for 10 or 20 years would unnecessarily burden those responsible for their care. - Which are the premise indicators?

for the reason that, since, Inasmuch as

What is a conditional statement?

"If...then...." statement form. Its not an argument but they are similar. One part is the antecedent, a sufficient condition. Other part is the consequent, a necessary condition. In the conditional statement , the antecedent is sufficient to ensure the consequent is also true.

Invalid deductive argument

A DEDUCTIVE argument that the conclusion does not follow from the premises with necessity even it it follows.

Unsound argument

A deductive argument in which one of the premises are false and is also INVALID.

Sound argument

A deductive argument that is valid and all true premises.

Cogent argument

An INDUCTIVE argument that is STRONG, TRUE premises, and has not ignored an important piece of evidence for a different conclusion.

Syllogism

An argument consist of 2 premise, 1 conclusion. Also called deductive arguments.

Categorical syllogism

An argument with 2 premises dealing with relationship between categories of things. A deductive argument

Causal inference

An inductive argument that draws a conclusion about the effect of a cause or an effect. Causal relations can only be known with probability.

Generalization

An inductive argument that draws a conclusion about the whole group based on a small sample of that group.

Argument based on signs

An inductive argument that draws a conclusion based on a message produced by an intelligent being. Messages can be in error.

Prediction

An inductive argument that makes a conclusion about the future based on past facts. Can never be certain about the future.

Argument from Analogy

An inductive argument whose conclusion is based on a comparison between 2 similar objects or states of affairs. The matter of the degree makes comparing several things with probable reasoning.

Argument from authority

An inductive argument whose conclusion is based on an expert or witness testimony. They could be lying or mistaken.

As indicated by the fact that many great works have stood the test of time, it follows that future great works will also display similar staying power. This is because the future tends to resemble the past, and given that great books all have certain qualitative characteristics in common. - Which are the premise indicators?

As indicated by, because, and given that

How to check the strength of an inductive argument?

Assume premises are true even though they are conceptually false, then determine if the conclusion would be true. If the premises are true, then the conclusion is likely true so it is a strong argument. If the conclusion does not follow from the premises with likelihood, then it's a weak argument.

A conditional statement: If Bob Marley was a famous reggae star, then Bob Marley was a Rastafarian. - Which is the consequent?

Bob Marley was a Rastafarian.

Which is the necessary condition in this conditional statement: If Bob Marley was a famous reggae star, then Bob Marley was a Rastafarian.

Bob Marley was a Rastafarian.

A conditional statement: If Bob Marley was a famous reggae star, then Bob Marley was a Rastafarian. - Which is the antecedent?

Bob Marley was a famous reggae star.

Which is the sufficient condition in this conditional statement: If Bob Marley was a famous reggae star, then Bob Marley was a Rastafarian.

Bob Marley was a famous reggae star.

A starfish is either an echinoderm or an anemone. Thus, it follows that a starfish is an echinoderm, because a starfish cannot be an anemone. - What form of argument is this?

Deductive Argument since its a Disjunctive syllogism as it uses the form "either....or...." statement. We can assume this item must be something so if its not a particular thing then it must be true that its something else.

If Friedrich Nietzsche suffered from a syphilitic infection, then he was killed by a stroke. Since it is well documented that Nietzsche suffered from a syphilitic infection, it follows from this and from the preceding conditional statement that Nietzsche was killed by a stroke. - What form of argument is this?

Deductive Argument since its a hypothetical syllogism as it only 2 premises with the form "if...then..." statement. Since we conclude something happened as both pieces of evidence are definitely true.

If aliens exist, then we must fear an invasion. Aliens do exist. Therefore, we must fear an invasion.

Deductive since its a hypothetical syllogism since it uses the form "if...then..." statement. Since something did exist then we must do something.

A shopper buys a product for $7.78 and pays with a $10 bill. Therefore, the shopper should receive $2.22 in change. - What form is this argument?

Deductive since the argument is based on math.

Strength

Determines the reasoning of an INDUCTIVE argument. The evidence that do give reason the conclusion is true is a strong inductive argument. If the conclusion does not follow from the premises with probability it is a weak inductive argument.

What makes a Valid argument?

If premises are true even if in context it's not, then determine whether the conclusion would therefore have to be true. All True Premises and True Conclusion. If conclusion is false even though premises are True, it's invalid.

The Odyssey and the Iliad were both written by Homer. Since the Odyssey is heavily laden with Greek mythology, it follows that the Iliad is probably also laden with Greek mythology. - This type of argument is?

Inductive argument from Analogy since it depends on a comparison between 2 similar things.

Abraham Lincoln's top hat is on display at the Smithsonian Institution in Washington, D.C. But the hat is tattered and worn. It can be inferred from this that the hat was handled and mistreated before it came to reside in its protected environment at the Smithsonian.

Inductive argument from a causal inference since the conclusion depends upon a causal connection drawn between an effect and its supposed cause. Based on the conclusion there is a comparison of the caused past and the effect today.

I have eaten at Cafe La Bouffe three times and ordered three different main courses. Each time, the main course was overcooked and dry. Every main course at Cafe La Bouffe is probably served overcooked and dry. - This type of argument is?

Inductive argument from generalization since it makes a conclusion about a whole group based on using a smaller sample of that group.

Riding a motorcycle is similar to riding a bicycle. Since it is important that you wear a helmet while riding a bicycle, it is also important that you wear a helmet while riding a motorcycle.

Inductive since it's based on an argument from analogy.

Bob is a skydiver. Every time Bob has jumped from a plane, his parachute has opened. Therefore, his parachute will also open on his next jump. - What form is this argument?

Inductive since its based on a prediction

Since all apples are blue in color, and navel oranges are a variety of apple, it follows that navel oranges must necessarily be blue in color. - Is it a deductive/inductive argument? Check Validity/Soundness or Strength/Cogency

It is deductive, valid, and unsound. It is deductive as it is a categorical syllogism. It is valid since if the premises are true, the conclusion is true. It is unsound since the premises are not all true even though the argument is valid.

An aardvark is either an insect or a bird. Since an aardvark is certainly not a bird, it follows that an aardvark is an insect. - Is it a deductive/inductive argument? Check Validity/Soundness or Strength/Cogency

It is deductive, valid, and unsound. It is deductive since it is a disjunctive syllogism. It is valid since assuming premises are true, conclusion is true. The premises are not all true so it would make it unsound.

Because Alaska is south of California, and California is south of Mexico, it follows that Alaska is south of Mexico. - Is it a deductive/inductive argument? Check Validity/Soundness or Strength/Cogency

It is deductive, valid, and unsound. It is deductive since its from definition. Its valid since the premises are true, the conclusion has to be true. It is unsound because even though the argument is valid, the premises are not true as they are all false.

An atomic clock is extremely accurate. Therefore, if you read a clock that gets its time from an atomic clock, then the time will be accurate.

It is inductive, strong, and cogent. It is inductive since its a casual inference. It is strong since the premise is true the conclusion would also be true. It is cogent since the argument is strong and all premises are true.

There is a large crack in Philadelphia's Liberty Bell. From this, we can conclude that there was a defect in the bell's craftsmanship. - Is it a deductive/inductive argument? Check Validity/Soundness or Strength/Cogency

It is inductive, strong, and cogent. It is inductive since its a causal inference. It is strong since the premise is true the conclusion would also be true. It is cogent since the argument is strong and all premises are true.

All positive whole numbers are rational numbers. Since -2 is a rational number, it follows that it is a positive whole number.

It is invalid since the premises are both true but the conclusion is false by definitions of positive and negative numbers. Since its invalid its also unsound.

Since there have never been any major earthquakes in the San Francisco Bay Area, it is unlikely that there will be a major earthquake in the San Francisco Bay Area anytime soon.

It is strong and does not have all true premises. It is uncogent. It is uncogent since the evidence in actuality is false. It must be sound and all true premises.

In the world of technology, Moore's Law is a generally accepted principle that states that the maximum number of transistors per given area on a circuit board will double every two years. Therefore, in six years it is likely that we will be able to have eight times as many transistors on a circuit board as we are currently able to produce. - What is the strength and cogency?

It is strong and has all true premises. Is it is Cogent. The premises make the conclusion likely to be true. it is strong. Since all premises are true its Cogent.

Diet Coke and Diet Sprite are both sugarless soft drinks. Since Diet Coke is sweetened with an artificial sweetener, and since Diet Sprite is made by the Coca-Cola company, it follows that Diet Sprite is probably sweetened with an artificial sweetener also. - What is the strength and cogency?

It is strong and it has all true premises. So it is Cogent.

Since Texas is a northern state, and Texas is south of North Dakota, it follows that North Dakota is a northern state. - What is its Validity and is it Sound?

It is valid and does not have all true premises. So, it's unsound. Even though the argument is valid, the argument is unsound since the premise is not true.

If Alaska is part of the contiguous United States, then Alaska borders another state. Alaska does not border another state. Therefore, Alaska is not a part of the contiguous United States. - What is its Validity and is it Sound?

It is valid and has all true premises. So it is sound. The argument is valid and all of the premises are true which makes it a sound argument.

Since the moon takes fewer than 28 days to orbit the earth, it follows that the moon must make at least one full orbit around the earth every month. - What is its Validity and is it Sound?

It is valid and has all true premises. Therefore it is sound. The conclusion follows by its necessity from the premises.

After the First Transcontinental Railroad was completed, a golden railroad spike was driven to commemorate the feat. Since railroad spikes often last for many years, it is likely that the golden spike still remains where it was originally driven. - What is the strength and cogency?

It is weak and has all true premises. It is uncogent. It does not seem likely something to be stay there for many years. The evidence does not makes the conclusion seem probable. It is uncogent since the argument has to be strong with all true premises.

Boise is a city in Idaho, and Idaho is a province in Canada. It follows that Boise is a Canadian city.

It's Valid despite the content being false. But the statements makes sense leading the premises guaranteeing a True conclusion.

Since x minus y equals 8, and y equals 7, it follows that x equals 15.

It's Valid since the conclusion follows from the premises with math necessity.

There are 33 states in the United States of America. Therefore, the United States has an even number of states. - Is this Valid or Invalid?

Its invalid since it is impossible for the premises to be true and the conclusion false. Let's assume it is true, the conclusion that there is an even number would not be allowed since the premise states it is not even.

All elephants are fish, and all fish are tigers. Therefore, all elephants are tigers. - Is this Valid or Invalid?

Its valid since if the premises are true, the conclusion has to be true. Even though the context is false, the form makes it true and valid.

Types of Deductive Arguments

Math, Definitions, Categorical syllogism, hypothetical syllogism, and disjunctive syllogism.

If you are using tobacco, then you are using a additive substance. What kind of condition is using an additive substance?

Necessary condition as if you are using this, you must be using something else.

If you are drinking a Coca-Cola, then you are drinking a soft drink. What kind of condition is drinking a soft drink?

Necessary condition as the conditional statement is expressed by the consequent/result.

Hypothetical syllogism

Syllogism with an "If....then...." statement as 1 or both premises. A deductive argument

Either Mt. Dana or Mt. Lyell is the tallest peak in Yosemite National Park. But the tallest peak in Yosemite is not Mt. Dana. So we know that the tallest peak in Yosemite has to be Mt. Lyell.

The argument is a disjunctive syllogism.

If our flight is on a Boeing 747, then it is not on a Boeing 737. Since our flight is indeed on a 747, we know that it is not on a 737.

The argument is a hypothetical syllogism.

If rainwater has flooded the driveway, then we will have to take a shortcut to get to the house. Rainwater has flooded the driveway. Therefore, we will have to take a shortcut to get to the house.

The argument is a hypothetical syllogism.

There were four assignments in the course. Madeline received scores of 8, 7, 10, and 9 points out of a possible 10 points per assignment. It follows that Madeline received a total of 34 points toward her grade in the course.

The argument is based on math.

deductive argument

The conclusion are purported/does seem to follow from their premises with necessity/"has to happen." They reason based on necessary results/consequences.

Inductive argument

The conclusions are intended to follow/come after from their premises with probability.

The United States has been a world superpower for more than 400 years, due to the industrial revolution and due to the victorious outcome of the United States' involvement in the world wars of the twentieth century. Based on this history, it is likely that the United States will also be a major world superpower into the next decade.

This argument is strong although the premises are conceptually false. The conclusion can still be false, but the good evidence given shows that we have a reason to believe this argument making it strong.

The town of Riverside, Iowa, has a large sign indicating that this town will be the future birthplace of Captain James T. Kirk from the popular science-fiction television show Star Trek, and that his birth will occur sometime in the twenty-third century. Based on this sign, we should conclude that Captain Kirk will be born in Riverside approximately 200 years in the future.

This argument is weak even though there is a presence of a sign. The sign does not make it likely for something functional to be born later on since the conclusion is likely to be false.

Harry has always had an aptitude for history, geography, and social sciences, but he has always struggled with abstract concepts such as mathematics and physics. But Harry must take a college physics course to fulfill a general education requirement for his degree. Based on his academic track record, it is likely that Harry will be one of the top students in his college physics course. - Would this conclusion be true? Would it be a strong or weak argument?

This argument is weak since based from the conclusion, the premises doesn't seem to follow through.

Whales and trout are both multicellular organisms. So, from the fact that trout can breathe underwater, it follows that whales can probably breathe underwater also. - Would this conclusion be true? Would it be a strong or weak argument?

This argument is weak since the conclusion does not follow from the premises. They are not similar enough to allow the conclusion to follow through.

Science fiction encourages a healthy imagination. This imagination can help you envision different ways the world could be. Moreover, science fiction often presents an optimistic vision of the future. We may infer that science fiction is healthy for the development of your worldview. - Which is the Conclusion Indicator?

We may infer that

Conclusion Indicator Examples

thus, therefore, hence, consequently, as a result, so, accordingly, clearly, must be that, shows that, conclude that, follows that, for this reason.

Valid Deductive Argument

A DEDUCTIVE argument in which the conclusion TRUELY follows from the premises with a necessity.

Validity

Determines the internal reasoning of DEDUCTIVE argument.

Since the Constitution of the United States has been ratified by every state in the union, it follows that the constitution has been overturned.

It is deductive, invalid, unsound. It is an argument from definition. It is invalid since even though the premise is true doesn't mean the conclusion is true. It is unsound as argument is invalid.

Examples of Inductive Argument forms

Prediction, Argument from analogy, generalization, argument from authority, argument based from signs, causal inference.

Science fiction is healthy for the development of your worldview. Science fiction presents an optimistic vision of the future. Imagination can help you envision different ways the world could be. Science fiction encourages a healthy imagination. - Which is the best described as the conclusion of the argument?

Science fiction is healthy for the development of your worldview.

How to check if an argument is cogent?

See if the Argument is STRONG, if its weak its UNCOGENT. If its STRONG, ALL premises are TRUE and Conclusion is TRUE.

Disjunctive Syllogism

Syllogism with an "Either...or...." statement as one of its premises. A deductive argument.

Premise Indicator Examples

because, since, for, for example, for the reason that, in that, given that, as indicated by, due to, owing to, this can be seen from, we know this by