1. Here, the best interpretation is that the poll result is being presented as a reason (i.e., a premise) for believing the conclusion that the institution of marriage is in trouble. So:
P1: 70% of Canadians now think a child can be raised well even if she only has contact with one parent.But, if the person presenting this argument thinks P1 should lead us to C, she must be relying on something like the assumption that the main reason people got married in the past was because they thought they had to in order to have children and bring them up well (otherwise, it's not clear why the poll results are relevant to the conclusion). So, the whole argument is something like:
C: The institution of marriage is in big trouble.
P1: 70% of Canadians now think a child can be raised well even if she only has contact with one parent.
MP2: The main reason people got married in the past was because they thought you had to in order to raise children well.
C: The institution of marriage is in big trouble.
2. The argument is not logically strong. Why not? Because logically
strong arguments must be either deductively valid or inductively strong
and the argument given is neither.
You can tell it's not deductively valid because it (more or less) commits the fallacy of affirming the consequent. Even if it's true that all successful businessmen are aggressive, it doesn't follow that all aggressive people are successful businessmen. P1 clearly doesn't tell us only successful businessmen are aggressive. As such, George could be one of those aggressive people who aren't successful businessmen. So, even if P1 & P2 are true, the conclusion could be false. The argument isn't deductively valid.
Is it inductively strong? There's no good reason to think so. Neither P1 nor P2 tells us that most aggressive people are successful businessmen. Hence, even if P1 and P2 are true, it doesn't follow that George is probably a successful businessman. So, the argument isn't inductively strong either.
A common problem with this question was that people would discuss whether P1 was actually true, but that's not relevant. What matters isn't whether P1 or P2 is true, but the relationship between the premises and the conclusion.
Another common problem was forgetting the definition of inductive strength.
The definition isn't that the conclusion is possibly true if the
premises are true, it's that the conclusion is probably true if
the premises are true. There's a big difference.
3. This was a tricky question. You might be inclined to think that the argument can't be deductively valid because whenever all the premises are true, the conclusion will be false (since it contradicts one of the premises). But, it's actually still possible for the argument to be valid because it may be the case that one of the argument's premises contradicts one of the other premises and, if that's so, the argument is valid even if the conclusion contradicts one of the premises. E.g.,
P1: Jefferson was President of the U.S.A.The thing to remember here is that if all the premises of the argument can't be true at the same time, the argument is valid no matter what the conclusion of the argument is.
P2: Jefferson was never President of the U.S.A.
P3: It's Thursday.
C: It's not Thursday.
4. To answer this one, all you need to keep in mind is what the slippery slope fallacy is. It's when an argument makes a dubious case that some relatively minor event will set in motion a chain of events leading to a major event. That is, the s.s. fallacy is committed only by arguments with the form:
P1: If A then BBut notice those are cooperative premises not independent ones. If the premises were independent they wouldn't be telling us about a chain of events. So, an argument with independent premises can't commit the s.s. fallacy.
P2: If B then C
P3: ...
P25: If Y then Z
C: If A then Z
5. This was also somewhat tricky, although the answer to it appeared in the solutions to the sample midterm. Here, you need to remember the definition of soundness. A sound argument is one that is deductively valid and has true premises. Notice that some arguments that beg the question are deductively valid, namely those ones that explicitly rely on the truth of their conclusion in one of their premises. E.g.,
P1: It's MondayThis is a bad argument in that it's incredibly uninteresting, but it's valid because there's no way to make all the premises true without at the same time making the conclusion true.
C: It's Monday
Now, all we need to do with such an argument to make it sound is make the premise true. The best way to do this is to pick a premise that can't be false. E.g.,
P1: Either it's Monday or not.This is deductively valid and the premises of the argument (i.e., P1) are all true, so it's a sound argument.
C: Either it's Monday or not.
6. The answer I was looking for was that the argument commits the fallacy of equivocation. The equivocation is on the word 'discrimination'. When people talk about banning discrimination, they mean people being denied things based on skin colour, gender, cultural membership, etc. But in subsequent sentences, when the arguer speaks of people discriminating he just means making choices. This undermines his argument since even if we agree (as I'm sure we do) that people should be allowed to make choices, we still aren't led to think people should be allowed to deny things to others based on skin colour, etc.
You could also describe the fallacy as a case of the straw man fallacy. As I've just noted, by switching the meaning of discrimination, he misrepresents the position of those who want to ban discrimination. They certainly don't think making choices should be banned.
A few people suggested the ad hominem fallacy, but that doesn't really
work. The arguer's opponents aren't being attacked here. Disagreeing with
someone isn't the same as attacking him.
7. The best answer here is that the arguer has committed a causal fallacy (specifically, the post hoc fallacy). The arguer seems to assume that because the spanking preceded success, it must have caused it. But, by this line of reasoning he could probably prove that getting cavities caused his success.
Another suggestion made by a few of you was false dichotomy. Here, the reason given was that the arguer seems to assume that either a person becomes a success by means of spanking or doesn't become a success at all. As you pointed out, even if spanking does cause success, there may be other ways of becoming a success. There's something to this suggestion, but this answer isn't quite right. The problem is that it's not clear the arguer is relying on this false dichotomy. All the arguer needs to think is that spanking is a cause of success in order for him to think that it's a bad idea to ban spanking.
Yet another suggestion was equivocation. Some of you thought that what
the people who want to ban spanking have in mind is serious physical abuse,
while the arguer probably has in mind an occasional minor slap on the behind.
Again, there's something to this suggestion, but it's not quite right.
The arguer doesn't give us any clear indication of what he means by 'spanking'.
Furthermore, some people really do want to ban all spanking.
8. Here, the best answer is false dichotomy. The argument is:
P1: Either the Bible is what it says it is (the word of God) or it is a horrible evil lie.Some of you suggested the argument begs the question, but that doesn't really work. Nowhere in the above argument is the conclusion assumed in the premises. In fact, the argument is structurally quite sound. P2 & P3 clearly imply that the bible cannot be a horrible lie. If that's so, then P1 clearly leads us to the conclusion that the bible must be the word of God. All of that works without us ever needing to assume that the bible is the word of God. As some of you pointed out, we might challenge P3, but, while that's true, that doesn't prove the arguer is begging the question. Instead, the problem lies in the choice presented in P1. Surely, there are other options. The bible might have been written by people who thought it was true (but were wrong). In that case, the bible is neither a lie nor the word of God. Furthermore, the bible might be a collection of myths and legends that we can learn from. Again, if so, it's neither the word of God nor a horrible lie. In short, the arguer has misrepresented the alternatives given in P1 as though they exhausted all the possibilities. They don't. But once we fix P1 the argument doesn't work anymore. Even if we accept P3, we won't be forced to believe the bible is the word of God.
MP2: The Bible has done a lot of good.
P3: If something has done a lot of good, it cannot be a horrible lie.
C: The bible must be the word of God.