Is using analogies a bad logic reasoning?

Question

When discussing with someone, I like to take the argument they use and put it in another context, to see if it works, and if it doesn't, ask why the argument should be valid in one context but not in the other.

For example, recently someone told me that a particular party was against gay marriage because they were christians and they believed that the only valid marriage should be a christian (or religious) marriage. I told him that if they thought that, they also should stand against civil heterosexual marriages, as they are not a christian or a religious ritual. The usual response I get is something like "they are not the same". Of course I know they are not the same, the point I'm making is why the argument should be valid when talking about gay marriage, but not about civil heterosexual marriage.

My point is never about these analogies being the same, but about extrapolating paradigms to other situations so the argument is not set in fire through the context they desire.

Three questions about this:

1. Is my reasoning wrong?

2. If it is not, is there a name for this kind of reasoning?

3. Is it a fallacy to respond "the cases are not the same" but without pointing out what the differences are that make the argument not applicable in the other context?

My English is kind of poor, so if there is something not clear enough just ask in the comments and I'll try to make myself clearer.

Answer 1

I believe your argument strategy can be understood without thinking about analogies at all, assuming your example conveys well your general idea. I will show why and my answers will rely on that.

From your example, the person claimed the strong statement of the form "the only thing that satisfies property X is Y" (namely that the only marriage that is valid is christian marriage)¹. You were simply testing the person if they really believe in that strong statement, by checking other things beyond Y that perhaps could also have property X, in which case the person would be forced to admit that their original premise is flawed, forcing them to look for another argument. Looks OK to me.

Just don't forget that this is a strategy to counter the person's argument, but it doesn't mean you're right either. They can find another argument, perhaps by fixing their premise, replacing it with a weaker claim.

Answering your specific questions:

1. Is my reasoning wrong?

No. It's valid. You took the premise of "your opponent", which is a sentence of the form "For every X, P(X)", and tried to prove it is false by checking some specific X and seeing if "your opponent" backs down from this strong claim.

2. If it is not, is there a name for this kind of reasoning?

I'm not sure, but you could call it "disproving the premise by counterexample".

3. Is it a fallacy to respond "the cases are not the same" but without pointing out what the differences are that make the argument not applicable in the other context?

Recall that "the cases are not the same" is just a statement, and statements can't be fallacies (only arguments can). But clearly this sentence is being mentioned with an implicit reasoning that "therefore I should not have to agree with that". And now, it's still not exactly a fallacy in my opinion, but definitely a bad argument for several reasons:

a. "the cases are not the same" is a trivially true statement if taken at face value: as you said, obviously they are not the same, strictly speaking. But that they are not the same is irrelevant, given that they basically claimed that "every marriage except a christian one is invalid", so it should still apply to that as well.

b. Considering the above, most likely the person meant something else, implicitly, such as "when I said 'the only one', I meant 'the only one among the ones in a certain group'" and "they are not the same" is implicitly saying that your suggested counterexample is (conveniently) not in that group. Too many implicit ideas and definitions (what exactly is that certain group?)

In short, "they are not the same" is irrelevant if taken at face value and too imprecise, full of implicit ideas, to be convincing. I'd suggest replying "what do you mean?" until they either change their premise to exclude your suggested counterexample (at which point you can follow up with 'why are you excluding that?' or trying another counterexample) or they find a way to convert that sentence in an explicit argument.

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¹ I used the term "strong statement" because it is a statement that claim something about many things (namely every type of marriage, claiming that it is either christian or invalid).

Answer 2

There is nothing right or wrong about the use of analogy as such. It is really only a statement. It says A is to B as C is to D. There is no argument, no logical inference. The analogy is valid, correct, persuasive, illuminating depending on whether (as a matter of fact, not of logic) A really is to B as C is to D.

An analogy always depends on some respect, or aspect, or feature by virtue of which it holds or fails.

So I might say that in respect of political power President Putin (A) stands to Stalin (B) as President Xi (C) stands to Mao Zedong (D). Putin is an autocrat and Stalin was a absolute dictator'; Xi is an autocrat and Mao was an absolute dictator. (This is not a statement of personal politics, be aware.)

Or I might say that in respect to the intake of oxygen gills are functional to a fish as the nose is functional to animals.

In your own example : in respect of religious status, a gay marriage stands in the same relation to a religious marriage as a civil heterosexual partnership stands to a religious marriage.

Whether this analogy is valid, correct, persuasive, or illuminating depends on whether the relevant claim can stand up against criticism. But the mere use of analogical reasoning as such is not 'bad logic'. As such it contains no logical error since it simply states or claims that a relationship holds good; it involves no argument, though it could be used in an argument if joined to other statements or claims.

Answer 3

Use of analogies is a great way to explain your argument to someone. But it leaves you open to exactly this counter argument : Your analogy is flawed. Whether your analogy is flawed or otherwise.

In this case your analogy is flawed, because religious weddings, and civil weddings are different things. Civil weddings are (usually) secular.

But a lot of Christians are against civil weddings of any kind. They consider them illegitimate. But then, Christians are against a lot of things, I find.

Answer 4

Yes it's a bad way of reasoning.

I think it depends on how skilled the person is in using Logic. Or how far fetched the example is. So I tend to say no it isn't a good way. Don't we sometimes get convinced by the beauty of the example instead of the logic. As we overestimate our logic skills and think the example checks out.

Averroes says in his Fasl al Maqal that there are 3 common ways of reasoning and one should explain in the way the other party finds best.

One of them comes to assent through demon­stration; another comes to assent through dialectical arguments, just as firmly as the demonstrative man through demonstration, since his nature does not contain any greater capacity; while another comes to assent through rhetorical arguments, again just as firmly as the demonstrative man through demonstrative arguments.

Logic is a skill. So if the other person isn't skilled in using Logic I would say analogies are a bad way to "convince" or "question" people. What I sometimes say is we are discussing my example. But the crux of the matter is and you explain the "hidden" or obscured thing you wanted to say within your example. (and then you switch to another way of reasoning). It happens often that examples is a dot so far away people can't connect it to the thing your talking about.

that said I thing this isn't the case in your discussion.

A christian marriage doesn't mean both parties have to be christian. When a jew marries a christian for example. This marriage would be "a christian marriage" or "mixed marriage" even tough both parties are not christian. You could ask the person when isn't it an christian marriage anymore. Once one party claims he doesn't believe in God? When both parties are of the same gender?

If someone dislikes joining "unchristian marriages" but joins "Muslim weddings" it might seem weird, until the person tells you he sees all wed Muslims as legitimate "christian" weddings. In your case you hinted to religious weddings being okay. So therefore atheist are in the same boat as gay weddings yet are treated differently. Maybe there are other reasons then only it not being "christian" why the person doesn't wanna go.

Which means your example has shown the person can't base it solely on gay marriages being "unchristian" onless he says non-religious weddings are more christian and there are shades to weddings and there "christian-degree" and he stops going at certain shades.