Hi Granny Magda
then that would be an argument from incredulity? That's fascinating. I'm sure glad that no-one around here has written anything like that recently.
yes that would be an argument from incredulity.
similar is argument from ignorance:
quote:
It must be {x} because I do not know of any other explanation
A different explanation could already exist in our knowledge base, but the author of the argument is unaware of it (or chooses to be ignorant of it).
Learning about logic is fun
Indeed, and one of the things that I have learned more about on this site.
A good reference I use is
http://onegoodmove.org/fallacy/toc.htm
While it does not cover all logical fallacies (if that is conceivable), it does present them in the format of the op: definition, examples, ways to show the fallacy is not valid in the particular argument.
For instance:
quote:
Appeal to Authority
(argumentum ad verecundiam)
Definition:
While sometimes it may be appropriate to cite an authority to support a point, often it is not. In particular, an appeal to authority is inappropriate if:
- the person is not qualified to have an expert opinion on the subject,
- experts in the field disagree on this issue.
- the authority was making a joke, drunk, or otherwise not being serious
A variation of the fallacious appeal to authority is hearsay. An argument from hearsay is an argument which depends on second or third hand sources.
Examples:
- Noted psychologist Dr. Frasier Crane recommends that you buy the EZ-Rest Hot Tub.
- Economist John Kenneth Galbraith argues that a tight money policy s the best cure for a recession. (Although Galbraith is an expert, not all economists agree on this point.)
- We are headed for nuclear war. Last week Ronald Reagan remarked that we begin bombing Russia in five minutes. (Of course, he said it as a joke during a microphone test.)
- My friend heard on the news the other day that Canada will declare war on Serbia. (This is a case of hearsay; in fact, the reporter said that Canada would not declare war.)
- The Ottawa Citizen reported that sales were up 5.9 percent this year. (This is hearsay; we are not n a position to check the Citizen's sources.)
Proof:
Show that either (i) the person cited is not an authority in the field, or that (ii) there is general disagreement among the experts in the field on this point.
References:
Cedarblom and Paulsen: 155, Copi and Cohen: 95, Davis: 69
:: Note that the "argument from hearsay" listed above is also known as the
appeal to anonymous authority. Curiously, citing the fact that a paper has passed peer review means an appeal to anonymous authority (the reviewers).
:: Note further that appealing to "the majority of biological scientists" as validation for the theory of evolution is also treading into the
Appeal to Popularity (argumentum ad populum).
The real test of validity of a conclusion lies in the evidence - objective empirical evidence - that substantiates the premises and in the proper construction of the logical deductions.
If the structure is valid, then the conclusion follows from the premises, and then (and only then) the truth of the conclusion is based on the truth of the premises: if the premises are true then the conclusion is true.
Normally, in science, we cannot be guaranteed that the premises are true, only that they approximate truth to the best of our (current) knowledge, and thus the conclusion/s are equally tentative as approximations of truth.
invalid vs false
There is frequently confusion between invalid and false in these debates (and I think this is a large part of the issue in the proceeding debate over the appeal to authority).
A logical argument that is flawed in the structure is invalid, and this is essentially the problem with logical fallacies.
Invalid means that the conclusion is not properly derived from the premises, but it does not mean that the conclusion is necessarily false.
Strip away the invalid structure and premises, and you are left with an unsubstantiated guess rather than a derived conclusion.
If it cannot be shown that this guess is actually false (ie -- objective empirical evidence shows the earth to be billions of years old, and this falsifies any unsubstantiated guess that the earth is less than 10,000 years old), then it is possible that the guess is correct, even though there is no evidence for it. This could range from the possibility of guessing heads or tails on a flipped coin to the possibility of guessing the winning ticket to win a lottery from millions of tickets available.
Enjoy.
Edited by Zen Deist, : enlgis
™ Version 4.2
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