If an analogy is appropriate–if the logic is legitimately transferable–such a “backfire” should be fair. Desirable, even, from the perspective of clarifying the underlying principles.
Or we’re just accustomed to the break down, because language is inherently “abstract” and an analogy usually is attempting to use concrete imagery to lessen the abstraction. Because we can “see” a concrete analogy better than an abstraction, it becomes easier to argue over what we’re seeing than to deal with the initial abstraction. This is the beauty and the pain of imagery.
So - are you all saying that a debate needs an analogy like a fish needs a bicycle? 
If you think of a debate as an oyster, then analogies could be the grain of sand or grit that produces a pearl…
Debate on the SDMB is like an ogre…they often stink and make you cry, but if you leave them too long in the sun they shrivel up and turn brown.
Analogies are the only debate tools.
Rules of logic are forms of analogy that we call by a different name. Modus ponens is just a fancy name for a particular analogy.
“If something is a human, it is mortal.
Socrates is human.
Therefore, Socrates is mortal.”
is analogous to
“If x is an integer that is evenly divisible by 4, then it is evenly divisible by 2.
16 is an integer evenly divisible by 4.
Therefore, 16 is evenly divisible by 2.”
One is about people and finite lifespans. One is about numbers. Their subject matter could not be further apart. Nevertheless, they clearly have something in common. What they share is the relationship among their parts. They share an arrangement of parts that we call “modus ponens”. (Most possible arrangements of parts don’t have names, but some of them do.)
The key point in working with an analogy is determining what features are relevant and what features are irrelevant. Consider two analogies to same-sex marriage that have been used on this board:
- Changing marriage laws so that two men can marry is analogous to changing marriage laws so that a black person can marry a white person.
- Changing marriage laws so that two men can marry is analogous to changing marriage laws so that a person can marry a washing machine.
The first analogy illuminates, because in the most relevant ways the two situations are similar, and there are no significant relevant ways in which the two situations are dissimilar.
The second analogy fails to illuminate because in the most relevant ways the two situations are dissimilar.
HOWEVER, the first analogy was not the end of the argument. Setting it forth is a claim that must be defended, and that can be attacked. It so happens that this analogy has proved persuasive in court case after court case in which judges have referenced Loving v. Virginia in striking down laws banning same-sex marriage.
The second analogy, technically speaking, wasn’t the end of the argument, although it was so terrible that it should have been; eventually people stepped forward to explain the relevant ways in which the situations are dissimilar.
I think that the value of an analogy is not in ending a disagreement; rather, it gives an arena in which to hash out the disagreement. A good analogy provides a good arena, a bad analogy a bad arena.
I agree. If you reject forced pregnancy, for instance, on the grounds that a person is entitled to complete bodily autonomy no matter the stakes, then there’s no obvious reason this principle shouldn’t carry over to the draft. Rejecting one while supporting the other thus reveals a lack of internal consistency and it’s valid for a debate opponent to pounce on it. Is one’s belief about a subject based on an biased emotional response? Or does it derive from sound reason?
In my case, I was against both mandates. But in considering the analogy, it made me see the bias in my stance towards forced pregnancy.
There’s a fair amount of confusion in this thread about analogical reasoning. Arguments from analogy are inductive arguments, not deductive arguments. Deductive arguments are valid or invalid: if the presumed truth of the premises guarantees the truth of the conclusion, then they are valid; otherwise, they are invalid. A valid argument with premises that are in fact true is sound.
Validity, invalidity and soundness do not apply to inductive arguments, including analogical arguments. These concepts refer to a necessary relationship between premises and conclusion, whereas inductive arguments reason from premises to probabilistic conclusions. If the premises of an inductive argumeent are assumed to be true they do not thereby guarantee the truth of the conclusion. Rather, we say that an inductive argument is strong—not valid—if the presumed truth of the premises makes it likely that the conclusion is true; otherwise, the argument is weak. The stronger the premises, the greater the likelihood that the conclusion is true. If a strong inductive argument contains premises that are in fact true, then the argument is cogent.
So, for example, *modus ponens * is a valid form of deductive argument, not an inductive argument. If the premises If p then q and p are true, then the conclusion q must be true. An argument from analogy is different. It reasons that if A and B share properties a, b and c, and if A also possesses property z, then it is likely that B shares property z as well. The more similar A and B are in relevant ways—that is, the more relevant a, b, and c are to the inference being made—the greater the likelihood that the conclusion B possesses property z is true. A strong analogical argument makes use of shared properties that are relevant to the comparison and conclusion, whereas a weak analogical argument does not.
A strong analogical argument: Wolves are furry, social canines that bear their young live; dogs are furry, social canines; thus, dogs probably bear their young live as well. The conclusion is not guaranteed by the presumed truth of the premises, but is simply more likely to be true. The argument is strong because the analogy makes use of shared properties that are relevant. A weak analogical argument: Joe’s iPhone is a black 4S with a purple case and a cracked screen; Mary’s iPhone is also a black 4S with a purple case; thus, Mary’s iPhone probably has a cracked screen too. The argument is weak because the analogy is weak: the shared properties are irrelevant to the inference.
So arguments from analogy are perfectly good inductive arguments when the premises refer to shared properties that are relevant to the inference one is trying to make. But they are inductive arguments, and so they at best make the conclusion likely to be true. They are not deductive arguments, and so their premises do not guarantee the truth of a conclusion, even if they are in fact true.
Well firstly I think you’re misusing the term “inherent”. If analogies are only flawed when used incorrectly, then that is not an inherent property.
OK, so why is that not useful in a debate?
Debates are not some separate realm of the universe which is always adversarial.
In theory at least people are trying to get a point across to each other and that is a form of education – both parties are trying to explain something (usually…I will concede that some of the times a debate can be merely cheering one side and booing the other). So, why not use analogies to help in that aim, if, as you say, they are an effective learning tool?
I think that this is the important point. Analogies can be extremely useful to explicate a point in a debate; they simply fail to prove any point.
Again: arguments from analogy are inductive arguments that are as strong or as weak as the premises adduced for their conclusions. The analogical argument is a staple of inductive reasoning—and thus of science—and as such can indeed “prove a point” in the probabilistic manner of all inductive arguments. To assume that it is somehow illegitimate because it is not deductive is to miss not only the proper place of analogical arguments, but to miss the very nature of inductive reasoning generally.
Yes. I would go as far to say as they never prove anything. What they do is explain and clarify, a useful aspect of communication. So yes, use analogies - but don’t rely on them.
Cross-post: Subterraneanus: Show me a non-trivial valid argument wholly reliant upon analogy. (Hey, maybe I’m wrong.)
And some people like teddy bear like bodies, some like svelte, some like them all and and some are asexual and find all of them inappropriate. What one person finds a travesty of an analogy will cause another person to say “oh, now I see what you were getting at.”
Again: analogical arguments are inductive, not deductive, so they are neither valid nor invalid. Rather, they are strong or weak, depending on how well their premises support their conclusions probabilistically.
This topic is usually covered in the first week or two of any introduction to logic class. I know, as I’m a logician (and philosopher of science), FWIW.
In my view (though it seems to be controversial) science itself is built on arguments from analogy. You can’t do science unless you assume that certain similarities between things will make other similarities between those things more probable.
[waves]
Not a logician here, also very small fry in the field (no publications or nothin’) but I do teach intro to logic and my dissertation involved philsci stuff.
Thank you. I backpeddle. I was going to say that as inductive arguments go, a solid factual grounding will almost be more compelling than an approach using analogy. But I think some of this might be confirmation bias: the best analogies are simply swallowed and not recognized as such.
This freshman level philosopher recommends this article on analogies, or at least the first few paragraphs: I’ve only read the beginning. Analogies can be vital during the discovery phase of scientific investigation, but they also play a justificatory role. The strength of the latter arguments vary widely.
I’m still inclined to recommend that analogies play a supplemental and supportive role in debate, based on experience if no longer categorical characterization. As for scientific investigation, yeah I’m a big fan of intuition and analogy.
Also, if anybody would like to cite a good intro text on logic, I’d be interested.
Subterraneus, thanks for a very interesting series of posts!
I do think it’s a good question MfM asked, slightly modified: can you give an example of a strong non-trivial argument that is wholly reliant on analogy?
Excellent thoughts, but it seems like you want opponents to argue in good faith, and with logic and reason, rather than rhetoric, and any other weapon available. Whilch is another topic of course.
Yes, but you are simply describing what happens, that isn’t an argument against the tactic.
Exactly, that is exactly right. But your argument that it is a poor debate tool is just pointing out that it is an awful tactic, it doesn’t actually convince that it should not be used.
It’s like (and yeah, I know exactly what I am about to do), it’s like your opponent in a fight just hit you in the nutsack with a frozen herring, which really hurt, and the crowd is cheering, and you point out that a frozen herring, especially with combined with an illegal groin hit, is a poor tool to use in a fight. The problem with this, is you are saying it through clenched teeth, while on the ground in pain.
This assumes there even exist a neutral bystander. Or even a bystander at all. Or that your opponent is interested in an actual debate.
So very very true. An analogy, or anyting really, can be used against you.
But math actually has real value, math is useful, math is valuable.
But Schrödinger’s cat isn’t an analogy at all! It has nothing to do with quantum mechanics, much less is it an analogy to explain QM!
But, by using it as an example you have actually opened the door to a chance for real understanding, of why analogies are a poor tool at times.
Schrödinger used the illustration of a cat being dead and not dead at the same moment to debunk the current view put forth by the Copenhagen interpretation. It wasn’t an analogy to explain it, and yet now that is the common view of what he intended. How ironic. (and if you ever thought, that dead/not dead at the same time thing is absurd, you would be right)
Now that is funny because it’s true.
Exactly. Unless one assumes that where there are relevant similarities between events there are likely others, one cannot even begin to frame a coherent view of the world as a unity of causal connections, and so one cannot even begin to do science. Hume of course argued famously—and to many persuasively—that this unity of causal events is not a necessary connection between events—the unity of the world is not logical—but merely the habitual expectation that the future will resemble the past, for no other reason that that it always has.