This reference provides some of the basic points made in Chapter Three. But it doesn't include everything of importance! Please spend the time working through all the tutorials! Often details for working homework problems -- the only good preparation for exams! -- is available in the tutorials. Even if you can do this weeks homework without doing them all, there may be material in later units that will be very hard without a clear understanding of all that going on in the tutorials.
Contents: Section 1: "Ampliative" Reasoning and Inductive Argument Types; Section 2: Informal Argument Diagramming; Section 3: Informal Fallacies of Relevance; Section 4: Informal Fallacies of Presumption; Section 5: Informal Fallacies of Ambiguity
1. "Ampliative" Reasoning and Inductive Argument Types
Informal reasoning typically leads to a conclusion by means of some educated guess-work. Maybe we should call this something like detective work. It takes evidence and amplifies it. (Think CSI, if you watch TV.) Let's review what we know from chapters one and two.
Formal reasoning (of deductive logic) manipulates the statements of evidence and performs something of a calculation on them in virtue of their form or sentential structure.
(Think about the simple "process of elimination" argument for Chris's B grade: "Either A or B but not A, so B".)
Informal reasoning (of inductive logic) interprets the evidence to form a conclusion. This thinking amplifies the evidence -- often by generalizing, predicting, or uncovering the best account of this evidence.
(Think about figuring out that Chris is in love. This may be a "best guess" but it may be a reasonable one.)
Think about all the arguments we symbolize in SL as good examples of deductive arguments. Keep in mind, say, the arguments about Bush (e.g., If he's US president, then he is a US Citizen. He is US president, so...). Then:
Another little diagram
to keep in mind, then, is this.
For a deductive argument:
Sound = Valid + No false premises.
Let's compare this to our inductive concepts:
Inductive arguments are just as common. The example about our conclusion that Chris has fallen in love is an example. It's an attempt to give the best account of the evidence...it could be wrong, maybe Chris is faking it, but we're trying to give the likely cause of his behavior here, not the only possible one. That's the big difference between inductive and deductive. And we can picture it this way:
So, for an inductive argument:
Cogent = Strong + No false premises.
Inductive Argument Types
There are various sorts of informal, inductive arguments. Here are six kinds.
All argument by these informal, inductive means is holistic. One attempts to render the best all-things-considered judgment. One might call this the best account or best interpretation of the data. Sometimes this is called "abductive" thinking = inference to the best explanation. But I think that "best interpretation" is more general. So, when rendering a conclusion, it may be best to have an 8th, overall category:
2. Informal Argument Diagramming
In order to analyze and evaluate an informal argument, we need tree diagrams as a tool to spatially represent complex interconnections. Let's look just a bit more at that tool.
First, here's that old argument attributed to me...and maybe I give it too much weight? Maybe we should be more skeptical about this claim that this is good, cogent reasoning?
I just claimed that my argument was cogent. That would mean the it's a strong one with true premises. But is it really? I'm not so sure. Let's start considering potential problems...just like you should for any real-life reasoning.
To begin, I don't know if there are other factors for quality food besides the ones of taste and health. Maybe some would say that chocolate is not such a great food for humans because it is a bit expensive for most of the world. Others would say that we exploit the third world growers when we force them to harvest the cocoa bean.
But, at least for today, I'm going to deny all of this. In fact, I've just been assuming (and you have too?) that health and taste are the only important factors for assessing the quality of a food. This is a kind of missing premise. It may not be true, but for this reason it's good to try and make our hidden assumptions explicit. Then we can examine them!
Try this...we add the missing premise with the button (just type in what you think is missing and you'll get the missing premise in gray:
But, I'm still not ready to evaluate this argument. We need to think some more. (So, I've taken away my claim that it is cogent.)
In fact, I suspect you'd come up with problems with this argument and conclusion if you had to....Let's see:
Argument and Rebuttal
We have had our fun with the chocolate argument. But you may well want to object before it is taken too seriously.
Let's go back to the earlier strong claim about the cogency of this argument. Look, you may say, some California journalist and some OU philosophy prof argue about the importance of eating chocolate. But they are not the experts on health. I am! (Let's suppose you're a nurse or otherwise have expertise in this matter.)
You may want to suggest a counterargument...
Objection: It may be that chocolate contains some health promoting antioxidants, but as well its high fat content can contribute to migraines, acne and obesity.
Point-Counter Point, Argument-Rebuttal
Suppose that you and I are arguing a bit about my old chocolate argument. Here's "my" argument and "your" contrasting one.
Notice that your conclusion (blue) is more or less the opposite of mine.
Your argument, a rebuttal to mine, has a conclusion that is a counterpoint to my point.
(Also notice that I choose two different argument schemes to represent your argument. I don't think the decision matters much. I'd count either as correct.)
Araucaria allows you to mark counterpoints in rebuttal arguments. Here are the directions. First, drag an arrow from your counterpoint to the original point (as though your rebuttal gave a reason for my point rather than its opposite). You'll get this:
Funny, the program doesn't make this look so good. But you clean that up when you make your point the counterpoint to my conclusion.
Second, click on your counterpoint and then on the rebuttal button: and you will get this:
Notice that my argument just got switched to the right and yours to the left. (I didn't program A3...don't blame me!)
Best Overall Interpretation of the Evidence?
We need to be able to analyze and evaluate the various sorts of inductive arguments. Our Araucaria Tool is just a way to illustrate this analysis and evaluation. But it can be useful. Here's a way to see the bottom line.
So, sadly, it's not very clear that this argument is cogent.
3. Informal Fallacies of Relevance
|Fallacies of Relevance|
|Arguments that give the illusion that premises support a conclusion while instead only making irrelevant assertions. Often the assertions are relevant to some related matter. (I try to use fairly generic terminology and description here so that the reader can utilize Web resources to greatest benefit.)|
|Appeal to Force||The arguer threatens some kind of harm to those not accepting his or her conclusion. The threat may be implicit.||"Believe me or I'll flunk you."|
|Appeal to the People||The arguer attempt to "support" a conclusion but bases this only on sentiments of popularity and the need to belong. There are two important subcategories. We use Teall's lingo here:|
|Bandwagon Appeal...the appeal to join in with "everyone" (arouse the passions, mob mentality, us v. them--we all should hold together in our thinking)||"Buy Ajax, most everyone does."|
|Snob Appeal...the appeal to the "in crowd"||"Shop Rochester Villiage...where the posh browse and buy"|
|Appeal to Pity||elicit pity in lieu of reasons||"I deserve a passing grade because otherwise I won't be able to graduate."|
|Argumentum ad hominem||An attempt at counterargument or rebuttal, but fallacious because the counter is against the person rather than against the reasons he or she adduces.|
|Abusive ad Hominem: A Character Attack in lieu of evidence against the alternative position.||"Hah! He's a philanderer so his views on logic are all wrong."|
|Circumstantial ad hominem: Dismissive of someone's claims because of their circumstances. It's fallacious because the claims themselves are not rebutted.||"She's a professor, so her defense of the U. is no good. She's just biased."|
|Tu Quoque ad hominem: claim of hypocrisy in lieu of reasons. "You too" are doing it; so don't give me reasons against the thing.||"You say don't do drugs. But I've seen you smoke. Thus drugs are fine."|
|Ignorance||Some claim is not proven true, so it's denial is accepted.||"Ha! I'm right. You can't prove me wrong."|
|Red Herring||Irrelevancies presented to throw one "off the scent"--always an attempt to counter another argument. Usually there is a "subtle" change of subject making the it appear that the issues at hand are being addressed.||Student to Instructor: "Halpin, you say we should spend more class time reviewing homework. But think about the importance of spending time at home on homework. You need to do homework on your own to really learn."|
|Straw Man||The misrepresentation of another's position in attempt to unfairly discredit it. (This seems to be the normal mode of political discourse in the U.S.)||Instructor to Student: " You say we should have fewer problems assigned. So you really think that you should just be able to sit around all day and night, drink away your lives and amount to nothing. That's just wrong. So, I'll assign the problems."|
|Unqualified Authority||An argument based on "authorities" who really are not trustworthy in the circumstances. Perhaps they are biased, outnumbered, or just out of their area of expertise.||"Halpin tell us to eat chocolate. Therefore, we should."|
4. Informal Fallacies of Presumption
|Fallacies of Presumption|
Arguments that give the illusion that premises support a conclusion by leaving important aspects of the reasoning unspoken and mistaken.
|Begging the Question||Assuming one of the mains points at issue, while trying to hide this fact.||Circular Reasoning: "God is real because the bible says so; and the good book is all true because it is divine inspiration."
Hiding the main Point: "Harming sentient beings is wrong so we shouldn't eat shrimp." (hidden assumption about sentience of shrimp)
|Complex Question||A question which conceals a presumption...best to see these as two part questions.||"So have you finally stopped partying away your life?"|
|False Dilemma or False Dichotomy||Premises presume that there are only a few possibilities when there are many.||"You study all day or you'll flunk."|
|False Cause||Using mere correlations or other weak evidence for causality.||"You made it rain, I saw you scream at the heavens minutes before the storm!"|
|Hasty generalization||Generalizing without enough evidence, perhaps based on an unrepresentative sample.||"The first two time the die came up 6. Therefore it always does."|
|Suppressed Evidence||An inductive argument is "all things considered". If an arguer knowingly and deceptively keeps relevant considerations out of the argument, then the reasoning is fallacious.||"It's a beautiful island, great views, great swimming, you should buy it" says the agent, neglecting to mention that the island is submerged by the tides every week or so...|
|Unreliable or Unqualified Authority||An argument based on "authorities" who really are not trustworthy in the circumstances. Perhaps they are biased, outnumbered, or just out of their area of expertise.||"Halpin says that we should eat chocolate; he must be right he's an OU prof."|
|Weak Analogy||Presuming that a few minor, similarities can mean complete similarity. We have discussed many reasons for the failure of analogical reasoning: The main ones are relevance of similarities and disanalogies. See 3.1 and 3.2 for details.||"The university is like an army, so when the philosophy professor says 'believe me about what is good', I should say 'yes sir or yes ma'am'!"|
5. Informal Fallacies of Ambiguity
|Fallacies of Ambiguity|
|Arguments that give the illusion that premises support a conclusion only because of unclarity in their meaning. (I try to use fairly generic terminology and description here so that the reader can utilize Web resources to greatest benefit.)|
Fallacies of Meaning
|Amphiboly||An ambiguous premise misleads due to faulty grammar.||"Headline: 'Zoo Staff Mothers Abandoned Chimp'. So, clearly, their staff should be punished."|
|Equivocation||Misleading reasoning based on a word or phrase with different meanings.||"Socrates is a man, so too is Plato. Socrates is man, so Socrates = man. Plato is man, so Plato = man. Therefore, buy the properties of identity, Socrates = Plato, indeed we all are one."|
Parts/Wholes Reasoning Problems
|Composition||Mistakes properties of the part as properties also of the whole.||"My brain can't really think, because my neurons don't think, they just electro-chemically signal."|
|Division||Mistakes properties of the whole as properties also of the parts.||"The table is visible, so all its parts are. Therefore, the atomic theory of matter must be wrong."|