Talk:Cogency

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Factual Accuracy Dispute[edit]

This article has the definitions for "cogent" and "strong" backwards. A strong argument is one in which the premises, if true, would make the conclusion probable. A cogent argument is one that is strong and has all true premises. When compared with a deductive argument, "cogency" is analogous to "soundness." I'm a bit busy right now to make the necessary changes, but will revisit the article tomorrow if no one does it first.Simoes 02:37, 2 November 2005 (UTC)

Since the Wikipedia article on Inductive logic does not specify, I would be interested to see a source on this. --Jdz 04:52, 28 December 2005 (UTC)
I finally got around to making the changes. I googled for sources and came up with a page from Carnegie Mellon University's philosophy department website [1]. --Simoes 21:27, 28 December 2005 (UTC)
That link gives me an 404 error. So I cannot verify what you say. --Deleet (talk) 22:09, 1 November 2009 (UTC)

Hurley's (2000) 'A Concise Introduction to Logic' 7th ed. (a long-time standard) defines 'cogent' as "an inductive argument that is strong and has all true premises". A 'strong inductive argument' is an inductive argument such that it is impossible that the premises be true and the conclusion false. Laymen's 'Power of Logic' gives the same defn for cogent.

There are deviants. For example, Govier's 'A Practical Study of Argument' requires "acceptability" instead of truth in the defn of 'cogent'.

Re. the sourced definition of "cogent" as "an inductive argument that is strong and has all true premises". This was what was in the article before I edited it. I shall put it back in the light of this source on one condition: That you cite a page number.

The definition above for "strong inductive argument" is wrong. The definition cited is the one for a deductively valid argument ("it is impossible that [all] the premises be [sic] true and the conclusion false"). It seems that the author is confused or, more probably, that you quoted him wrongly. It is definitely not a mainstream definition of "cogent". --Deleet (talk) 22:10, 1 November 2009 (UTC)

Jcblackmon 23:28, 11 June 2007 (UTC)J. Blackmon

There does not seem to be a single standard usage for this. See for example Reason and Argument (1999) by Richard Feldman. There he defines Cogency as the property an argument has such that the truth of the premises would make the truth of the conclusion probable. But an inductive argument is there defined as being a cogent argument whose premises one has good reason to believe (so like the acceptability standard mentioned above). I don't know enough to know whether one of these readings is more common than another. —Preceding unsigned comment added by 72.195.138.143 (talk) 13:51, 1 July 2008 (UTC)
The definition offered by R. Feldmen is identical to the one that I added to the article just 2 mins. ago. Do you have a page number? Otherwise I will not add it as a reference. Also, R. Feldman is not a logician but an epistemologist (I happen to have read a book of his by chance), so he is not a terrible good authority on logic. Even though he is/was a professor of philosophy. The author of Fallacyfiles, the source that I cited, is better qualified. http://www.fallacyfiles.org/aboutgnc.html --Deleet (talk) 22:10, 1 November 2009 (UTC)

Begging the Question[edit]

  1. Water freezes at 0 degrees Celsius
  2. Therefore, water freezes at 0 degrees Celsius

"is a sound argument, because it is a valid argument, all of its premises are true, and it has a true conclusion, but it isn't good, because it doesn't prove anything and is a case of begging the question."

How is this "begging the question"? It's just a tautology (A implies A). --Jdz 04:52, 28 December 2005 (UTC)

I nixed this material because question begging is a feature of a deductive argument, not an inductive one. However, the fallacy of begging the question is where an argument contains in its premises the conclusion. This, of course, involves a tautology.--Simoes 22:22, 30 December 2005 (UTC)


"question begging is a feature of a deductive argument, not an inductive one" this is probably not true.

(A & B) implies A ... this is deductive
(A & B) implies B ... this is (also) deductive
So question begging is a feature of a deductive argument, not an inductive one.
Kmarinas86 06:00, 2 January 2007 (UTC)


Marble Choice[edit]

As far as I can tell, the marble pulling example is not a cogent argument. Without any prior information about the contents of the bag, I do not see how what has already been pulled out has any barring on what is most likely to be pulled out next. If 100% of the marbles pulled out were red, then it would seem to be more and more likely that all the marbles are red, thus making it more and more likely with each pull that the next marble will be red. But once it is established that not all marbles are red, then I don't think we can make any probabilistic determination of what the next marble is most likely to be, unless we know how many marbles were in the bag to being with, or what the distribution of red to non-red marbles was.Northern Bear 09:16, 4 May 2007 (UTC)

Eh? What did you do to that brought you to that conclusion? Simões (talk/contribs) 10:20, 4 May 2007 (UTC)
Do? I didn't do anything. It is what I think.
But lets consider the example. You pull out 100 marbles, 95 of them are red and 5 are white.
Supose the bag originally contained exactly 95 red marbles. The chance that the next marble will be red is zero.
Supose the bag originally contained exactly 5 non-red marbles. The chance that the next marble will be red is 100%.
Supose the bag contained 100 billion marbles, half of them red, and half of them white. The probability that the next marble pulled will be red, is essentially 50%.
There is litteraly an infinte number of possible combinations of marbles in that bag. Having pulled 100 does not help us to make any predictions about what is left, unless we know how many there were to start with, or what the distribution was, or what the probability of different starting bags was. Northern Bear 15:42, 6 May 2007 (UTC)
OK. Sorry. Never mind. I was wrong. My first gut instinct was that you can't predict what is left, based on what has been withdrawn, unless you know how many marbles there were to start with. After doing the math though, and with some help, I now realise that regardless of how many marbles are in the bag to begin with, pulling 95 red marbles indicates that there is a very high chance that the majority of any remainging marbles would be red. So the example is valid. —The preceding unsigned comment was added by Northern bear (talkcontribs) 14:25, August 20, 2007 (UTC).

Good argument[edit]

Why does this redirect here? A good argument is either a cogent (strong + true) inductive argument or a sound (valid + true) deductive argument. Logical argument would probably be the best place for both good and bad arguments. Richard001 (talk) 06:11, 26 January 2008 (UTC)

There was a section on what a good argument is, but it was unsourced and so I removed it. And by the way, there are no true or false arguments. That's a category error. --Deleet (talk) 15:51, 2 November 2009 (UTC)

Edit 1. Nov. 2009[edit]

I removed a lot of unsourced text. I found a definition of "cogent" and replaced the one in the article by the one I found. I added a reference for this and added a reference section. --Deleet (talk) 21:58, 1 November 2009 (UTC)