Accused of a fallacy? Suspect a fallacy? Ask Dr. Bo and the community!

Quickly register to comment, ask and respond to questions, and get FREE access to our passive online course on cognitive biases!
Register!

one moment please...


Welcome! This is the place to ask the community of experts and other fallacyophites (I made up that word) if someone has a committed a fallacy or not. This is a great way to settle a dispute! This is also the home of the "Mastering Logical Fallacies" student support.


Dr. Bo's Criteria for Logical Fallacies:

  1. It must be an error in reasoning not a factual error.
  2. It must be commonly applied to an argument either in the form of the argument or in the interpretation of the argument.
  3. It must be deceptive in that it often fools the average adult.

Therefore, we will define a logical fallacy as a concept within argumentation that commonly leads to an error in reasoning due to the deceptive nature of its presentation. Logical fallacies can comprise fallacious arguments that contain one or more non-factual errors in their form or deceptive arguments that often lead to fallacious reasoning in their evaluation.

Contact Form



Send me a copy of this message
Send Message sending message...

Q&A Home Question

0

votes

image loading...
Guest

Unregistered

#fallacy
#logic
generalization
Fri, Feb 01, 2019 - 10:42 AM

modus tollens wrong conclusions

If it is the Holy Shroud (p) then it is ancient (q)
The shroud under examination is not ancient (not q)
So there is no Holy Shroud (not p)

Looks like modus tollens, but it is wrong, since the fact that one shroud is not ancient does not imply that there are no ancient shrouds, one of which could be the Holy one. Is this a "faulty generalization"?
Thanks.



Quick Comment On This Question (no login required):
Your comment below will be anonymously sent to the question owner, it will not be posted, and you will not get a response.

Send Comment sending comment...

3 Answers

0

votes

image loading...
Michael Chase Walker
Screenwriter, producer, mythoclast

Master Contributor

image loading...

Michael Chase Walker

Screenwriter, producer, mythoclast

Master Contributor

About Michael Chase Walker

Michael Chase Walker is an actor, author, screenwriter, producer, and a former adjunct lecturer for the College of Santa Fe Moving Images Department, and Dreamworks Animation. His first motion picture was the animated classic, The Last Unicorn.
Michael was an in-house television writer for the hit television series: He-Man, She-Ra, Voltron, and V, the Series. In 1985, he was appointed Director of Children's programs for CBS Entertainment where he conceived, shaped and supervised the entire 1985 Saturday Morning line-up: Wildfire, Pee Wee's Playhouse, Galaxy High School, Teen Wolf, and over 10
Print Fri, Feb 01, 2019 - 11:25 AM
I'm not seeing the Modus Tollendo - only the non sequitur.

Non Sequitur (also known as: derailment, “that does not follow”, irrelevant reason, invalid inference, non-support, argument by scenario [form of], false premise [form of], questionable premise [form of], non-sequitur)

Description: When the conclusion does not follow from the premises. In more informal reasoning, it can be when what is presented as evidence or reason is irrelevant or adds very little support to the conclusion.

The premise is faulty because it assumes there is only one holy shroud by stating it is "the holy shroud".
There could be many holy shrouds from many various faiths - both ancient and neoteric.
Now, If it was referring specifically to The Shroud of Turin that might be another claim.

But then we'd have to agree on what constitutes ancient, as well as what exactly is holy.

The Shroud of Turin has been determined to be a forgery from the Middle Ages. So, it's possible it is neither ancient nor
holy. That is if one dismisses frauds and hoaxes as unholy and that the Middle Ages are not ancient enough.
It's possible it could be an antique, but not ancient.

There are just too many factors here that do not follow logically.


2

votes

image loading...
Rich McMahon
Ye Olde Logician

Seasoned Vet

image loading...

Rich McMahon

Ye Olde Logician

Seasoned Vet

About Rich McMahon

Retired Chemist, Fortune 500 Co. Exec., and Wall St. i-Banker. Now a fledgling Playwright & lyricist. Currently living la Vida Meditativo on a mountain in CO.
Print Fri, Feb 01, 2019 - 12:47 PM
To simplify:

If it is the Holy Shroud (p) then it is ancient (q)
The shroud under examination is not ancient (not q)
So there is no Holy Shroud (not p) {WRONG!}

If it is the Holy Shroud (p) then it is ancient (q)
The shroud under examination is not ancient (not q)
So, the shroud under examination is not the Holy Shroud {CORRECT!}

Thus, this syllogism begs the question whether the Holy Shroud exists.

0

votes

image loading...
Michael Chase Walker
Screenwriter, producer, mythoclast

Master Contributor

Print Fri, Feb 01, 2019 - 01:59 PM
Much better!


Registered User Comments

former student
Friday, February 01, 2019 - 12:31:28 PM
@Michael Chase Walker: Actually I am referring to the onyl Holy Shroud (in case it existed of course) which was used to bury Christ.
So if the one being examined is more recent, it is not that. But it does not mean it does not exist. My point is not prove that the one in Turin is old or not, we could use any other example:
The corpse of Hitler must be 74 year old (or so). This corpse is 20 years old. So Hitler did not exist. A more general conclusion than: this is not the corpse of Hitler.

login to reply
2 replies
0 votes
 
Reply To Comment
working...
 

Michael Chase Walker
Friday, February 01, 2019 - 04:43:24 PM
Your premise certainly is a petitio principii (Loaded or begged) because it assumes (a lot!) that needs to be proven.

For instance, you claim:

"I am referring to the onyl (sic) Holy Shroud (in case it existed of course) which was used to bury Christ."

So, this is an Appeal to Common Belief fallacy.

You're not just assuming (ad hoc) that there is only one shroud and that it was holy but that it was specifically used to bury Christ.

Who knows? It could have been someone else's shroud, or as evidence suggests the greater probability of it being a proven hoax. Since there is no mention of a burial shroud in the gospels we have no idea whether there was one, two, three or none at all.

You're also assuming there was a Christ. Christos is Greek for the savior or messiah. Any survey of mythological literature would reveal there were many such christos, heroes, and messiahs throughout history and myth. Even in Jewish messianic traditions, there were many such candidates, such as The Persian emperor Cyrus who is the only foreigner in the Bible to be identified as the Messiah or anointed one of Yahweh, the Israelite God. So you're assuming we all know and agree whom you're referring to.

So your original premise is based on assumptions, common beliefs or more than one Special Pleading.

BTW, The Shroud of Turin was debunked and discredited by the Catholic Bishop Pierre d’Arcis as early as 1322 and Carbon Dating has shown it to be a relic from the Middle Ages since 1988. Since Rich McMahon correctly restated your syllogism in its proper logical form, I would simply reject the premise altogether as a special pleading.

Your reference to Hitler is very different (Weak analogy) since it is dealing with a proven historical figure and not mythological figures and dubious reliquary.

login to reply
 
0 votes
 
Reply To Comment
working...
 

former student
Thursday, February 07, 2019 - 03:00:57 AM
@Michael Chase Walker:
You are assuming that I am some sort of believer, which I am not.
You check my English, but not your Latin (modus tollendo??).
You have no idea of what logic is: an example of modus tollens with Santa Klaus would be perfectly fine.
Ignorance and arrogance often go together.

login to reply
 
0 votes
 
Reply To Comment
working...

former student
Friday, February 01, 2019 - 01:17:54 PM
@Rich McMahon: thanks Rich , that is what I meant. But I do not see a petitio principii here:
p is q; e is not q. Therefore there is no p at all.
How would you call this ?
The modus tollens correctly imply not p but in the sense that the observed evidence e is not p, not that there is no p at all

login to reply
6 replies
0 votes
 
Reply To Comment
working...
 

Rich McMahon
Friday, February 01, 2019 - 03:41:46 PM
Davide,

I think this boils down to proper application of Modus Tollens syntax:

If it is the Holy Shroud (p) then it is ancient (q)
The shroud under examination is not ancient (not q)
A. So there is no Holy Shroud (not p) [Improper]

If it is the Holy Shroud (p) then it is ancient (q)
The shroud under examination is not ancient (not q)
B. So, the shroud under examination is not the Holy Shroud

Syntax of MT: If p, then q. Not q. Therefore, not p.

Per above: 'A' is not consistent with proper MT syntax "not p"..... only 'B' is consistent with the "not p" syntax.

Illustration: Correct MT Syntax:

If Marie was born in France (p), then she is French (q) .
Marie is not French. (not q)
Therefore, Marie was not born in France (correct not p).

Illustration: Incorrect MP Syntax:

If Marie was born in France (p), then she is French (q) .
Marie is not French. (not q)
Marie was not born (Incorrect not p)

What do you think? Also, to your point about p not existing, there is no requirement I'm aware of that a MT premise must be true; in other words, "if P is True than Q is True" says nothing about falsehoods. However if P & Q are bivalent (both can be either true or false) and P can only be true if Q is true, than I believe the MT holds.

login to reply
 
0 votes
 
Reply To Comment
working...
 

former student
Friday, February 01, 2019 - 04:37:40 PM
@Rich McMahon: Thanks Rich.
I agree with last part on p not existing which is not a requirement but it was for Michael who pointed that out.

I understand the example about Marie. Let’s say that in MT not p in the conclusion should be particular and not general. But is there a name for this fallacy? Thanks a lot.

login to reply
 
0 votes
 
Reply To Comment
working...
 

Rich McMahon
Friday, February 01, 2019 - 04:56:30 PM
@Davide: I'm generally better at recognizing fallacies than naming them; it might be an example of "the fallacy of the undistributed middle". (Not sure whether this fallacy exists in Bo's lexicon.)

login to reply
 
0 votes
 
Reply To Comment
working...
 

former student
Friday, February 01, 2019 - 05:36:30 PM
@Rich McMahon: thanks Rich but would you agree it is a problem of inferring a general conclusion (no Holy Shroud) from a particular (this shroud is not ancient) premise (which is not acceptable)?
Could it be a sort of non sequitur?

login to reply
 
0 votes
 
Reply To Comment
working...
 

Rich McMahon
Friday, February 01, 2019 - 10:52:36 PM
@Davide: The non-sequitur is my favorite fallacy, meaning IMOP it is the closest thing to a Universal Fallacy that exists. Thus when in doubt, a reasonable fit can often be had when applying the NS. So, I really can't disagree. However, when dealing with syllogisms, or more precisely with MT syllogisms, I think it is better to cite a fallacy that deals with these specifically. Thus I encourage you to research the " Fallacy of the Undistributed Middle" and decide for yourself whether it applies.


login to reply
 
0 votes
 
Reply To Comment
working...
 

former student
Saturday, February 02, 2019 - 01:34:48 AM
@Rich McMahon: I checked it of course but I do not see it here because it happens in syllogisms which have a general premise like All p or every p. In our case it is a particular premise like one p is q; one x is not q so no p. Of course p and x have something in common (they are both shrouds) but x lacks q.
Thanks for your comment

login to reply
 
0 votes
 
Reply To Comment
working...



About Archieboy Holdings, LLC. Privacy Policy Other Books Written by Bo
 Website Software Copyright 2019, Archieboy Holdings, LLC.