Ex.
1. All laws require a lawmaker.
2. Galileo's principle of inertia is a law.
3. Galileo's principle of inertia requires a lawmaker.

Reasoning.
The arguer is equating laws of dynamics with laws of legality.

Ex.
A recent announcement on our college bulletin board was semantically ambiguous. It simply read: “Personal Security for Women Has Been Canceled for the Rest of the Semester.”

Reasoning.
Given the fact that our campus security chief had just resigned, it was not clear whether one should conclude that there would perhaps no longer be any security provided for female residence halls or that maybe a scheduled class focused on personal safety for women would not be meeting for the remainder of the semester. Without further clarification, one should not draw either conclusion.

Ex.
Suppose you heard the following statement uttered by one of the candidates in a hard-fought gubernatorial race: “If you knew that one of the candidates in this race was receiving money from illegal sources, would that affect your voting decision? Look into the matter and see where the campaign funds of my opponent are coming from. The facts might surprise you.”

Reasoning.
The speaker has made no accusation against the opponent that requires any kind of defense, but the power of suggestion has done its work.

Ex.
If a Catholic bishop were dealing with a situation in which a priest had been discovered to be “taking liberties” with young boys in his parish, he might caution all the priests in the diocese that “it is sinful for priests to take advantage of young boys.” If one reasoned that it is not sinful for priests to take advantage of young girls, it would be fallacious.

Reasoning.
It would be fallacious, since it would be unjustified by the context, to assume that the bishop is suggesting that it is not sinful for priests to relate sexually to young girls.

Ex.
At a faculty meeting several years ago, the president of our small college announced that our student enrollment figure was moving us toward a financially dangerous situation. He then suggested that we might improve our student retention rate if we would show more concern for some of our weaker students, some of whom were dropping out of school because of failing grades. In response to the presidents remarks, one faculty member indignantly exclaimed that he would quit before he would let the president force him to give a passing grade to a student who did not deserve it. The faculty member in this case gave his own specificity to the president's vague request to “show more concern for some of the weaker students.”

Reasoning.
Of course, if previous experience gave the faculty member reason to believe that “show more concern” was a euphemism for “don't fail any students,” then his interpretation would have been justified. In this instance, however, he is not.

Ex.
We must judge this issue by what the Bible says, not by what we think it says or by what some scholar or theologian thinks it says.”

Reasoning.
The radio preacher who made this claim apparently thought he was making an important distinction, but it is no distinction at all. If the Bible requires interpretation, and it does, then all of its readers are interpreters. The Bible or any other text doesn't say anything until it is interpreted by someone—either by a scholar, a theologian, an ordinary reader, or the radio preacher. Therefore, there is no intelligible distinction to be drawn between what the Bible says and what someone says it says. In this particular case, the preacher apparently thinks that he will tell us what the Bible says, but as a matter of fact, he will tell us merely what he interprets it as saying.

Ex.
A sign in front of a restaurant or service station with the words “Under New Management” is usually intended to convey to the passerby that the food or service will be better than in the past.

Reasoning.
However, no reason is given for believing such a claim. If we patronize such a place in the expectation of better food or service, we have committed the fallacy of novelty no less than the person who erected the sign.

Ex.
A person trying to quit smoking says, “surely one more cigarette will not make a difference.”

Reasoning.
The cigarette is not negligible.

Ex.
1. Each player for the Chicago Cubs is an excellent player.
2. The Chicago Cubs are an excellent team.

Reasoning.
Just because the players have talent, it does not mean they work together well as a team.

Ex.
1. The U.S. Congress represents every state in the Union.
2. Each member of the U.S. Congress represents every state in the Union.

Reasoning.
Just because Congress represents every state in the Union, it does not mean that each member of Congress represents every state.

Ex.
A case of treating contraries as if they were contradictories is also seen in one of the well-known sayings of Jesus: “If you are not for me, you must be against me.” A similar instance may be found in the claim that if one is not a theist, then one must be an atheist.

Reasoning.
Neither claim seems to allow for the alternative of neutrality or agnosticism.

Ex.
“But, officer, you shouldn't give me a parking ticket for parking here! People park here all the time and never get tickets. I myself have been parking here for several months. No one pays any attention to the “No Parking” sign in this alley.”

Reasoning.
The fact that it has been the practice not to obey or even to enforce a traffic regulation is not a good reason for concluding that it should not be obeyed or enforced.

Ex.
“My husband has been missing for more than ten years, but I know he is still alive. He just couldn't be dead.”

Reasoning.
It may be true that he is still alive, but this wife's wishing her husband to be alive provides no support for the claim that he is.

Ex.
If the rule with regard to X-rated movies shown at a drive-in theater is that “no one under the age of eighteen will be allowed into the theater,” it would be a misapplication of this rule for an attendant to refuse to allow a couple to bring their sleeping infant with them.

Reasoning.
The rule was not intended to be applied in such cases.

Ex.
Consider the following argument that is sometimes put forth regarding the Israeli-Palestinian conflict. “Both Palestinian and Israeli points of view represent extremes. Therefore, some kind of compromise must be the best solution.”

Reasoning.
Compromise may be the only way that this dispute can be finally settled, but it is a different thing to say that a compromise is the best solution in that conflict.

Ex.
“Smoking cigarettes is just like ingesting arsenic into your system. Both have been shown to be causally related to death. So if you wouldn't want to take a spoonful of arsenic, I would think that you wouldn't want to continue smoking.”

Reasoning.
Although it is true that both the ingestion of arsenic and smoking cigarettes have been shown to be causally related to death, there are some significant differences in the character of those causal relations. A single heavy dose of arsenic poisoning will bring about immediate death, whereas the heavy smoking of cigarettes would be likely to bring about premature death only as a result of a long process of deterioration or disease. In one case, then, death is immediate and certain; in the other, death is statistically neither immediate or certain.

Ex.
“Yes, I have heard that Dr. Reid is a very good gynecologist, but if I were a woman, I don't think I would go to him. I went to high school with him, and he had the biggest porn collection in the school.”

Reasoning.
The arguer here is using his past negative assessment of the doctor during his adolescent life as the grounds for a present assessment of him.

Ex.
After losing a boyfriend to another young woman, Sofia says: “Well, I was going to dump him anyway. It was getting boring having him around. I should have left him long ago; I just felt sorry for him.”

Reasoning.
Sofia is trying to deal with the fact that the relationship with her boyfriend is over. To make that break more personally palatable, she finds fake reasons to justify it to herself and to anyone who cares to listen.

Ex.
“Reporters keep the public informed, and we all know that a well informed public is necessary to bring about any semblance of justice. Besides, reporters keep public officials and others 'honest' by digging out the facts behind their claims and exposing them when they don't tell the truth or when they engage in questionable practices. Therefore, I think that the courts are grossly unfair to newspaper reporters when they force them to go to prison just because they won't reveal the sources of their information.”

Reasoning.
The weight of evidence in this argument supports the view that newspaper reporters perform a very useful and important service for their readers; however, it does not support the claim that the courts have been unfair to reporters.

Ex.
Many critics of gun-control legislation have argued that, because gun-control laws will not prevent criminals from using guns in the course of committing crimes, there is no good reason to pass such legislation.

Reasoning.
Those critics are using the wrong reasons to come to their conclusion against gun-control legislation. The proponents of gun-control legislation recognize that such legislation will probably have only a limited effect on the control of crime. They know that the serious criminal will not be significantly affected by the restricted sale and registration of guns. Since the legislation is proposed with full awareness of this limitation, it would not be fair or relevant for a critic to argue against it on those grounds. The legislation, however, could serve other very important functions, such as making guns less readily available as a means of settling domestic quarrels. Moreover, gun-control might have the effect of the number of accidental killings. Hence, in spite of its limitations, proponents think that there are very good reasons for passing legislation that would control gun use. A relevant argument against or criticism of gun-control legislation would be one that showed that the stated functions of the legislation could not be accomplished by enacting it or that some other more important principle was in conflict with the proposal (such as your second amendment rights).

Ex.
“Senator, if you think that the FBI has been engaging in unauthorized or illegal activities, why don;t we ask the Director of the Bureau and his staff to testify at this hearing so that we can get to the bottom of this matter? Who is in a better position to testify about FBI operations that the Director and his division heads?”

Reasoning.
The appeal to authority here might be proper in most inquiries concerning FBI operations; yet such testimony might be questionable if the inquiry were intended to evaluate charges of wrongdoing within the Bureau that might even involve its Director.

Ex.
“I'm going to buy the new Lady Gaga CD. It's been at the top of the charts for more than a month. It must be a good one.”

Reasoning.
What large numbers of people do or believe tells us nothing more than what large numbers of people do or believe. It tells nothing about the quality of the thing in question, least of all, the quality of a new CD.

Ex.
Student: “Professor Boltwood, why do we have to attend the guest lecture tonight, as it is outside class time and was not listed on the syllabus?”
Professor Boltwood: “Because that is what I require.”

Reasoning.
The student is asking why the class members are required to attend the extra lecture, but Professor Boltwood responds in an authoritarian fashion. He simply appeals to his power over the students to force their compliance. His argument is fallacious, for it implicitly issues a threat instead of defending the requirement with relevant reasons.

Ex.
“When I was in public school, we prayed every day at the beginning of the school session. It was a very meaningful thing for me. I just don't see why my children can't have the same kind of experience.”

Reasoning.
No counterargument is offered here that considers the more important principle at stake, addressed by the Supreme Court ruling that state-required prayer in public schools constitutes an “establishment of religion”; the only appeal made is to the comfortableness of a tradition.

Ex.
“Professor Beamer, are you sure you want to openly oppose this new curricular proposal? You know that both the president and the dean are pushing it pretty hard, and you don't have tenure yet!”

Reasoning.
This arguer is appealing to the self-interest of Professor Beamer, as a means of getting him to withdraw his opposition to the new curriculum. Since Professor Beamer obviously wants to receive tenure and the president and the dean have a lot to do with whether he will get it, it is being implicitly suggested that it would be in this best interest not to risk alienating the president and dean. The more important consideration, however, should be whether the curricular proposal deserves his support or opposition—apart from any consideration of self-interest.

Ex.
“How could you vote for Senator Withers? Every gay and lesbian organization in the state has endorsed him.”

Reasoning.
If the person being questioned is homophobic, this strategy of trying to assign some kind of guilt by association just might work, but it shouldn't. A person who let himself or herself be intimidated by such a fallacious appeal is just as guilty of irrational thinking as the emotional manipulator.

Ex.
“My experience with my ex-wife was so bad that I have no intention of ever marrying again. In fact, I wouldn't recommend marriage to anyone.”

Reasoning.
This reasoning is obviously based on a very small sample. This man's anecdotal experience with his wife is not a large enough sample for the conclusion.

Ex.
“A recent study of how Americans spend their vacations revealed that 52 percent of the people spend five or more days a year at ocean beaches.”

Reasoning.
This study was based on a sample of fifty thousand Virginians, drawn from every relevant subgroup of the population, but it is hardly representative. Most areas of Virginia are close to popular beaches within the state as well as in Maryland and North and South Carolina. For that reason, a disproportionate number of the residents of Virginia, when compared with people from many other states, vacation at a beach.

Ex.
Most of us have encountered the fallacy of the contrary-to-fact hypothesis in claims made about historical events: “If Hitler had not invaded Russia and opened up two 'fronts,' the Nazis would have won World War 2.”

Reasoning.
This is such a highly speculative claim that it is difficult to imagine how sufficient “evidence” for the claim could ever be produced.

Ex.
A typical campus cliché expressed by one student to another the night before an important test is: “Well, if you don't know it now, you never will.”

Reasoning.
No evidence is usually given for such a questionable claim; indeed, there is considerable evidence to suggest that the claim is false. As far as performance on tests is concerned, it is probably safe to say that a conscientious student might learn a significant amount of material during the hours immediately before the test.

Ex.
Jessie and Katrina are college roommates. Let us imagine them engaged in the following brief conversation:
Jessie: “Would you please turn off that music? I want to take a nap.”
Katrina: “I was just listening to a YouTube video of our brass ensemble.”
Jessie: “Listen to it some other time. I want to take a nap.”

Reasoning.
The implicit principle that most roommates accept is that one roommate's interest is not more important than the other roommate's interest, but Jessie is implicitly claiming that her interest is more important than Katrina's. Jessie is guilty of special pleading.

Ex.
“I think I will buy the car my neighbor is selling. He's had it for a couple of years, and it seems to run just fine. I like the color and the style, and he tells me it gets really good gas mileage.”

Reasoning.
These may all be good reasons to buy the car, but one of the key premises in an argument for buying a car is whether the car is in the appropriate price range. And that crucial information is missing.

Ex.
“You said that I would have to run the mile in less than six minutes to be on the track team, and I did. So why did I get cut from the team?”

Reasoning.
The arguer has assumed that meeting the eligibility requirement of being able to run a mile in less than six minutes would be a sufficient condition of being on the track team. Meeting the requirement, however, was only a necessary condition. The sufficient condition for being on the track team would probably include the meeting of other requirements as well.

Ex.
A radio preacher recently argued in the following way: “Marriage would be greatly helped if husband and wife would read the Scriptures together and pray together every day. No wonder divorce has increased so much! Family worship has dropped almost 30 percent in just the past fifteen years.”

Reasoning.
It is not likely that the rise in the national divorce rate could be sufficiently accounted for solely by data on family worship, even if the data were true. Because the reasons for the dissolution of a marriage are usually quite varied and complex, it seems highly questionable to reduce them simply to a change in worship patterns.

Ex.
“It's no wonder that Natalie makes such good grades. She's the teacher's pet.”

Reasoning.
It is much more likely the case that Natalie is the teacher's pet because she makes good grades. Based on our general knowledge of classroom dynamics, if Natalie is indeed the teacher's pet, it would seem highly unusual to treat her as a “pet” for reasons other than those related to her superior performance.

Ex.
Suppose that a college student is both obese and depressed. A typical analysis of such a situation might be that the obesity is causing the depression or that, because of the depression the student tends to overeat.

Reasoning.
A more likely explanation is that some underlying psychological or physical problem is causing both effects.

Ex.
“If we allow the government to limit the number of guns a person can buy each month, what's next? If they can limit guns, they can limit how much liquor, how much food, or even how many cars you can buy. They already tell us how many deer we can shoot. Next thing you know, they will even be telling us the number of kids we can have. They'll keep on until they control us.”

Reasoning.
There is no evidence here that any of these events are causally connected. In fact, it is difficult to imagine how such a connection might be defended. Although it is conceivable that good reasons might be found for putting limits on some of the things mentioned, it is not because they are causally connected.

Ex.
“It's been tails five times in a row. I'm sticking with heads.”

Reasoning.
There is no more likelihood that the next toss of the coin will be heads than that it will be tails, even though some of us would be inclined to believe it would be tails and just as many of us would be inclined to believe it is heads.

Ex.
Senator Winger: “Homosexuality is a learned trait. You don't have to be a homosexual. Your so-called studies that say it is something you're born with were fabricated by the radical left to try to force us to accept the gay lifestyle.”

Reasoning.
Senator Winger not only denies that there is any credible counterevidence to her claim, she also takes the further step of “explaining away” the evidence that is offered by saying that it is the work of leftist radicals. Not only is such an attempt at rebuttal not effective, it seems likely that the senator would not take seriously any evidence brought against her view.

Ex.
“Motorcycles are dangerous; they are noisy; only two people can ride at once; you can't ride them in cold or rainy weather; and in most states you are required to wear an uncomfortable helmet. I can't see why anyone would want to buy one.”

Reasoning.
The arguer has neglected to consider several factors relevant to the desirability of owning and using a motorcycle. A good argument would contain rebuttal premises that address these and other features of the motorcycle/auto debate.

Ex.
Suzanne: “Walking is one of the best kinds of exercise you can get. One should walk rather than drive whenever possible. For example, rather than drive over to the cafeteria to eat lunch, it would be more beneficial to your health to walk.
Sherell: “But I don't eat at the cafeteria.”

Reasoning.
Sherell is attacking an illustration that Suzanne used to make her point. The fact that the specific illustration does not fit Sherell's case is irrelevant to the basic thrust of the argument about the benefits of walking.

Ex.
Freddie: “I think we need to clean up this place tonight, Wayne. The landlord wants it to look decent when he shows it to a prospective tenant tomorrow. He said that he lost a prospective tenant he showed it to las week because it was so messy in here—especially the kitchen. He reminded us that we agreed in our contract that once we gave notice to vacate we would keep the apartment clean for showing prospective tenants.”
Wayne: “What does he know about “clean”? He's been wearing the same shirt for a week.”

Reasoning.
Wayne is not responding to the landlord's argument about keeping the apartment clean during the “show” period; he is using his negative assessment of the landlord's personal habits as a device to avoid dealing with the substantive claim at issue.

Ex.
“You can't believe what Professor Mahaffey has to say about higher salaries for teachers. As a teacher himself, he would naturally be in favor of increasing teachers' pay.”

Reasoning.
The fact that Professor Mahaffey is a teacher should not preclude him from giving an argument that deserves our serious consideration.

Ex.
Suppose that the golf pro at the country club tells you during tour first golf lesson that the first and most important thing to do in learning to become and effective golfer is to “keep your head down and your eye on the ball.”

Reasoning.
It would be fallacious to conclude that you are not being given sound advice, simply because the golf pro doesn't always keep her head down when she plays the game.

Ex.
A very clear case of misrepresentation that involves drawing unwarranted inferences can be seen in this short exchange between a proponent and an opponent of a plan to construct a new power-generating dam.
Marcia: “Unless we build a power plant in this area within the next ten years, we won't be able to meet the significantly growing demand for electrical power.”
David: “What you're saying is that you couldn't care less what happens to the plant life and wildlife in this area or even to human lives that might be dislocated by the building of this dam.”

Reasoning.
David has drawn an inference from Marcia's argument that is clearly unwarranted. In no way could one conclude from her argument that she is unconcerned about the possible environmental dangers and other disruptions that would be created by building the plant.

Ex.
A common way of committing the red-herring fallacy is to draw attention away from an argument or criticism that involves an undesirable situation by claiming that one should be satisfied with such a situation because “things could be worse.” Many of us have had the experience of complaining about the low or unfair wages we receive for our labors, only to be told by a parent or some older person, “Well, you could be making 35 dollars a week as I did when I was your age.”

Reasoning.
Although it is true that “things” could almost always be worse than they are, that is not the issue. Drawing attention to such a notion is simply a way to divert attention from the main point at issue and thus avoid the responsibility for addressing it.

Ex.
When a student noticed that his political science professor had used a questionable contrary-to-fact hypothesis in her analysis of a particular issue in class, he confronted her with it. Rather than examining the charge to determine whether it was a justifiable one, the professor, knowing that the student was a philosophy major, tried to blunt the force of the charge by saying: “Well, Socrates must have slipped into our class while we weren't looking. Now what did you say I did? Used a contrary-to-fact what? I didn't think philosophers were concerned about facts.”

Reasoning.
Since the other class members were amused by her ridicule of the student, the professor was able to avoid facing squarely the charge against the soundness of her reasoning.

Ex.
If thought requires a brain, then brainless creatures cannot think.

Thought requires a brain.
----------
Brainless creatures cannot think.

Ex.
If inland temperatures increase, then crops are damaged.

If crops are damaged, then we all suffer.
-----------
If inland temperatures increase, then we all suffer.

Ex.
If Persia was a mighty kingdom, Then Lydia was a mighty kingdom.
----------
If Lydia was not a mighty kingdom, then Persia was not a mighty kingdom.

Ex.
If there is growth, then the economy is recovering.

But the economy is not recovering.
----------
There is no growth.

Ex.
Either American Dennis Tito or South African Mark Shuttleworth was the first space tourist.

South African Mark Shuttleworth was not the first space tourist.
----------
American Dennis Tito was the first space tourist.

Ex.
Either American Dennis Tito or South African Mark Shuttleworth was the first space tourist.

American Dennis Tito was not the first space tourist.
----------
South African Mark Shuttleworth was the first space tourist.

Ex.
All A are B

No B are C
----------
No C are A

Ex.
Some A are B

All A are C
-----------
Some C are B

Ex.
No A are B

All C are A
-----------
No C are B

Ex.
All A are B

All C are A
-----------
All C are B

Ex.
All A are B

All B are C
-----------
All A are C

Ex.
All A are B

Some A are not C
-----------
Some B are not C