Fallacies of Weak Induction

Fallacies of Weak Induction can be differentiated from appeals to emotions in that they are actual attempts to support conclusions based on citing supporting evidence. However, a basic error in the argument prevents drawing a valid conclusion.
==Sweeping Generalization==
Also known as Accident - concluding that a legitimate generalization necessarily applies to a particular case.
Example:
: The Bible says 'Thou shall not kill', so capital punishment is morally wrong"
Capital punishment may be morally wrong, but the general rule is likely misapplied here.
==Hasty Generalization==
secundum quid, also small sample bias is a conclusion drawn upon a too small or non representative (not randomly drawn) sample. This usually is seen in arguers who overly depend upon Case study a matter of preferring interesting examples over boring statistics - (again, See Rush Limbaugh). It's a truism that one good case study example impresses people more than a book full of statistics - a phenomenon well studied in psychology. But remember - one of the main reasons for the salience of a case study is its uniqueness.
Speaking of psychology, this fallacy is known in social psychology as the availability heuristic. In short, its the overuse of conclusions drawn from what is readily available in memory - which essentially is the small sample bias. It's one of the reasons that good scientists stress the need to consider many hypotheses and the need to examine many sides of an issue.
Example: Consumer's Report may say this radio is the safest, but my brother Irving got a shock when he used it - so I say it's the worst"
One final note: In the 1920s, the people of the city of Chicago began to complain to their mayor about the incredible upsurge in crime in their city. The Mayor investigated the situation and found that, statistically, crime had dropped during his time in office. He presented this information publicly, only to be booed. Finally, he went to the newspapers and asked them to play down their sensationalist style of presenting criminal news. Soon after his public approval ratings sored...
==Anecdotal Evidence==
A specific form of Hasty Generalization. One of the simplest and widely seen fallacies is the belief that one can prove a point based solely on anecdotal evidence. For example: "There's abundant proof that God exists and is still performing miracles today. Just last week I read about a girl who was dying of cancer. Her whole family went to church and prayed for her, and she was cured."
It's quite valid to use personal experience to illustrate a point; but such anecdotes don't actually prove anything to anyone. Your friend may say he met Elvis in the supermarket, but those who haven't had the same experience will require more than your friend's anecdotal evidence to convince them.
Anecdotal evidence can seem very compelling, especially if the audience wants to believe it. This is part of the explanation for urban legends; stories which are verifiably false have been known to circulate as anecdotes for years.
==Fallacy of the Undistributed Middle==
These fallacies occur if you attempt to argue that things are in some way similar, but you don't actually specify in what way they are similar. Examples: "Isn't history based upon faith? If so, then isn't the Bible also a form of history?"
Often the illogic of an argument if made more clear when we substitute. For example, consider the same argument form, with a substitution:
"Islam is based on faith, Christianity is based on faith, so isn't Islam a form of Christianity?"
OR
"Cats are a form of animal based on carbon chemistry, dogs are a form of animal based on carbon chemistry, so aren't dogs a form of cat?"
==Argument from Ignorance==
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: "Of course the Bible is true. Nobody can prove otherwise."
Argumentum ad ignorantiam occurs when it's argued that something must be true, simply because it hasn't been shown to be false. Or, equivalently, when it is argued that something must be false simply because it hasn't been proven to be true. This fallacy is a particularly eggregious because it attempts to move from an admitted state of ignorance to a knowledge claim.
Note that this isn't the same as assuming something is false until it has been proved true. In fact, this presumption is the very opposite conclusion: it assumes that we are unable to make a statement while in a state of ignorance. In science, we assume that an unproven is unproven. In law, this is known as the presumption of innocence.
However, in scientific investigation, if it is known that an event would produce certain evidence of its having occurred, the absence of such evidence can validly be used to infer that the event didn't occur.
Interestingly, this fallacy is often recognized as a fallacy by the very ones who use it - when it is employed by an opponent. circumstances. For example, while an apologist may maintain that a belief in god is validated by a lack of negating evidence, the apologist himself has absolutely no problem whatsoever denying the reality of other gods without his requirement for negating evidence.
See also: "Correct by Default Fallacy"
==Argument from Silence==
The fallacious form of an Argument from Silence is the claim that since a historical personage/document does deny or rule out a claim, that this silence can be taken as consent. This is a form of argument from ignorance unless at can be shown that such a person would likely have taken some position on the matter.
A valid argument from silence, or an evidential argument of silence, can be made. For those for whom this claim appears controversial, consider: if there were no valid arguments from silence, then it would follow that no one could rule out any claim for which there was no evidence!
According to Gilbert Garraghan (A Guide to Historical Method, 1946, p. 149)
: To be valid, the argument from silence must fulfill two conditions: the writer[s] whose silence is invoked would certainly have known about it; [and] knowing it, he would under the circumstances certainly have made mention of it. When these two conditions are fulfilled, the argument from silence proves its point with moral certainty.
An example of a Fallacious Argument from Silence is given by Minicus Felix, a first century Roman writer whoe wrote about early Christians, claiming that they sacrificed infants:
"As for the initiation of new members, the details are as disgusting as they are well known. The novice himself, deceived by the coating of dough (covering a sacrificial infant), thinks the stabs are harmless. Then, it's horrible! They hungrily drink the blood and compete with one another as they divide his limbs. And the fact they all share knowledge of the crime pledges them all to silence. On the feast-day they foregather with all their children, sisters, mothers, people of either sex and all ages. Now, in the dark, so favorable to shameless behavior, they twine the bonds of unnamable passion, as chance decides. Precisely the secrecy of this evil religion proves that all these things, or practically all, are true."
An example of a valid Argument from Silence
Before Ignatius, not a single reference to Pontius Pilate, Jesus' executioner, is to be found. Ignatius is also the first to mention Mary; Joseph, Jesus' father, nowhere appears. The earliest reference to Jesus as any kind of a teacher comes in 1 Clement, just before Ignatius, who himself seems curiously unaware of any of Jesus' teachings. To find the first indication of Jesus as a miracle worker, we must move beyond Ignatius to the Epistle of Barnabas. Other notable elements of the Gospel story are equally hard to find. This strange silence on the Gospel Jesus which pervades almost a century of Christian correspondence cries out for explanation. It cannot be dismissed as some inconsequential quirk, or by the blithe observation made by New Testament scholarship that early Christian writers "show no interest" in the earthly life of Jesus. Something is going on here.- Earl Doherty's case for a non-historical Jesus.
==No True Scotsman Fallacy==
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Otherwise known as the Fallacy of Redefinition. Suppose I assert that no Scotsman likes to play checkers. You counter this by pointing out that your friend Angus likes to play checkers. I then say "Ah, yes, but no true Scotsman likes to play checkers.
This is an example of an ad hoc change being used to shore up an assertion, combined with an attempt to shift the meaning of the words used original assertion; as well as "counting the hits and forgetting the misses" -you might call it a combination of fallacies. Whatever you call it, its a nasty attempt to alter reality to suit one's needs.
The fallacy of redefinition is a key component of the argument style of Chris "Mad Dog" Russo, who can be heard on WFAN radio. A good example can be heard nearly every day. The most recent example was his challenge for fans to find "One small market baseball team that is competitive." Seeing that small market Arizona won the world series last year, and that other small market teams such as Atlanta and San Diego have appeared in the world series within the last four years, fans found this challenge rather easy to meet. They phoned in and listed these cities, as well as other cites such as Seattle and Oakland that appeared in the playoffs only last year.
Obviously, any logical person, so thoroughly refuted, would be compelled to immediately withdraw the ludicrous claim. However, Russo responded by stating that each of those teams had big budgets and therefore they were not small market teams. In other words, Russo re-defined the term "small market" from meaning "a smaller city with a smaller population" (which is what it really means) to mean "a team with a smaller budget." But any sensible person realizes that "small market" indicates nothing more or less than a small market - regardless of what the budget of the team is.
Radio hosts tend to use the logical fallacy of redefinition often, since it allows their arguments to become moving targets, safe from logical rebuttals. With their argument safe from logical debunking, they are free to continue to spout pure idiocy, unchecked. Even more perversely, they can claim that their argument has never been "refuted". The best way to catch such a rhetorician is to insist that he define his terms (he won't) and stick to this one particular issue. (he'll sidestep to some other issue immediately) However, if you can pin him down, he will back off - until the next caller.
==Ad Hoc==
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I'm thinking of putting this in the "Suspect Debate Tactics" section. The Ad Hoc fallacy occurs when we give an after-the-fact explanation to shore up an argument that has been negated by some new evidence and this explanation is made without restoring to an consistent policy, but solely because this explanation rescues the theory!
When new evidence falsifies a conclusion, rational thought requires abandoning a conclusion and clinging to reality. Ad hoc thinking requires abandoning reality and clinging to the conclusion.
The two most common examples in theological discussions are cries of "translation error" and "out of context."
The problem with the cry of "translation error" is that to be consistent, one would need to check the entire document for translation errors, especially points that are not under criticism.
The problem with "out of context" is that "context" is often a subjective claim to begin with. Unless a statement is completely in discord with the immediate passages preceding or anteceding the statement, going back for "further context" is questionable at best.
Often this ad hoc explanation is nothing more than a special plead, dressed up to look like an argument. For example, if we assume that God treats all people equally, then the following is an ad hoc explanation:
"I was healed from cancer."
"Praise the Lord, then. He is your healer."
"So, will He heal others who have cancer?"
"Er... The ways of God are mysterious."
The logical response would be "No... and that doesn't make sense, does it?"
See "Weak analogy".
==Saliency==
Saliency is a fallacy in which a dramatic event is taken to outweigh a significant amount of statistical evidence. This sort of "reasoning" has the following form:
Dramatic or vivid event X is more memorable. 
Therefore events of type X are likely to occur.
This sort of "reasoning" is fallacious because the mere fact that an event is particularly vivid or dramatic only means that an event will be memorable, it does not make the event more likely to occur, especially in the face of significant statistical evidence.
People often accept this sort of "reasoning" because particularly vivid or dramatic cases tend to make a very strong impression on the human mind. For example, if a person survives a particularly awful plane crash, he might be inclined to believe that air travel is more dangerous than other forms of travel. After all, explosions and people dying around him will have a more significant impact on his mind than will the rather dull statistics that a person is more likely to be struck by lightning than killed in a plane crash.
==Weak Analogy/False Analogy/Overextened Analogy==
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Also informally known as the Hitler Fallacy, a weak, overextended or false analogy occurs whenever two entities are considered comparable because of a superficial similarity. A typical analogy is usually drawn in the following manner:
Entity 1 is held to possess the attributes of A and B and C, Entity 2 is maintained to possess the attributes of A and B. Therefore, Entity 2 probably has attribute C.
However, any analogy made without a strong systematic, causal connection between possession of the attributes A and B AND possession of attribute C commits the fallacy of Weak analogy. An example may better clarify:
1) Hitler was a man who spoke German, wore a goofy mustache, and had an irrational hatred of Jews.
2) Einstein spoke German and had a goofy mustache - it follows that he had an irrational hatred of Jews.
This is a weak analogy because no causal connection can be drawn between speaking German and hating Jews (although BEING German and hating Jews might... no... of course not.) Not to sound like a broken record, but to hear fine examples of this, tune into Rush, between rehab visits...
The key element that a keen debater will learn from this entry is that the 'weak' or 'overextended' fallacy is often one drawn between an entity you support and an entity that shares superficial characteristics with your entity, plus one with clearly 'odious elements' that are not essential to the nature of the entity that you support or defend. For this reason, I call the overextended analogy the 'Hitler argument', for Hitler is the most popular historical felon used in the overextended analogy. Here is an example: Arguer: 'I believe in a woman's right to choose, therefore I support abortion.' Opponent: 'Gee, isn't that how Hitler would handle unwanted pregnancies?' Whether or not Hitler would handle the situation in a similar manner is not essential to this argument - after all, Hilter was also nice to dogs, so according to this logic, one would have to be mean to dogs to avoid being 'Hitlerian'. (By the way, just to show how off the mark this argument is, Hitler was AGAINST abortion.)
==Examining Weak/False Analogies==
In an analogy, we explain or define a phenomenon by making a comparison of this unknown entity to a known entity. An analogy is somewhat like a generalization in that it uses a specific, well known example, as its basis. However, whereas the generalization draws a conclusion about the whole class of objects from which the example is drawn, the analogy draws its conclusion about another specific example. The analogy makes the assumption, 'This unknown example is like that known example'. Now, the test of an analogy is this:
Is the unknown example like the known example in the -essential- areas being compared?
As long as the similarities lie in the areas about which the claim is made, argument by analogy constitutes proof. If the analogy draws its comparisons in an area not relevant to the claim, the argument will be faulty. Therefore, this fallacy occurs when a comparison between one phenomena and another is made based on a resemblance so superficial that the analogy clearly is nonsensical - i.e. there is no legitimate reason to claim that the two entities are similar. No logical evidence for the connection is made. Here is an example:
: "Why should we sentimentalize over a few hundred thousand Native Americans who were ruined when our great civilization was being built? It may be that they suffered injustices, but, after all, you | can't make an omelet without breaking a few eggs."
In order to make an omelet, one is required to crack open the eggs. In order to build a nation, it is not required that one rape and slaughter its native inhabitants.
====Incorrectly classifying an analogy false====
====The most common response to a valid  analogy will be to claim it is a false analogy. The argument may go: "The two situations are different because...", and then proceed to list an existing property that the two things in the analogy indeed do not share. However, this response may be a "false charge of fallacy" as analogies by nature compare two different things there are always some properties that A and B do not share, so it is tempting to pull up one such difference to try to disqualify the analogy. For the purposes of the analogy, however, it is important to check if that difference is relevant for the analogy or not.====
Category:Logic
Category:Informal Fallacies