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Old 17th February 2013, 12:52 PM   #1
RichardR
 
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Question about Logical Fallacies

I'm looking for opinions on something from the logicians in the group.

I've been debating someone called David Dilworth about his claim that a sentence in a pro-GMO piece contained six logical fallacies. Here is the sentence:

Quote:
“For the backers of the initiative to claim [ GMOs might be harmful ] as a finding of fact is an outright lie, and an outlandish attack on science.”

That sentence contains half a dozen fallacies : Ambiguity (twice), “Can’t Prove a Negative,” a Non-Sequitur (it does not follow), Contradiction, and “Proof by Assertion.”
The main claims I am interested in here are his claims of two ambiguity fallacies. (I don't accept his other four either, and if you want to discuss those then please look at his explanation of those - but I'm mainly interested in the ambiguity fallacy claim.)

Here is Dilworth's explanation for calling ambiguity fallacies:

Quote:
1. Ambiguity fallacy: His claim of an “attack on science” is ambiguous about what he means by “science.” Does he mean scientific methodology, reasoning or facts derived from experiment – or some combination? It does make a difference. (It is also possible he means GMO scientists – but that would add an additional fallacy of falsely equating scientists with ideas of science.)
2. Ambiguity fallacy: Nor does he define the careless way he uses the word “safe.” (The word “safe” is not explicitly in the offending sentence, however the sentence refers to its earlier use.)
Does he mean “not harmful” or that the harms are only relative to the benefits?
To me, any ambiguity in the meaning of "science" or "safe" are at most examples of careless writing, not fallacies. For it to be a fallacy, in my view, the argument must not support the conclusion due to the ambiguity.

My example of an actual ambiguity fallacy (equivocation) is "you have faith in science, therefore science is a religion." The ambiguity of the word faith can lead you to the wrong conclusion - the first definition (faith in science) is really trust, based on experience. The second definition (religious faith) is blind faith with no evidence. Someone could be fooled into thinking that science was a religion, due to the ambiguity.

I don't see the ambiguity Dilworth is talking about causing a false conclusion (ie that GMOs are safe, when they are not), not least because the words "science" and "safe" are only used once. For a fallacy IMO they need to be used twice, with different meanings in each case, but implying they are the same definition.

Links that seem to agree with me are this, this and this.

But maybe there is another way this could be a fallacy? Opinions? Am I right or am I missing some other way this could be a fallacy?

To be fair, read Dilworth's longer article on this subject.

Last edited by RichardR; 17th February 2013 at 12:58 PM.
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Old 17th February 2013, 10:43 PM   #2
phildonnia
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Just my two cents:

The sentence is certainly very problematic. I don't know what is meant by an "attack on science", and so I would agree that this is ambiguous. I can't tell whether it materially supports some argument without seeing the rest of the context. But I think the intended meaning would be better expressed by replacing "attack on science" with "demonstration of ignorance concerning scientific facts and methods". (Since one does not scientifically conclude that "X might be true" from the absence of evidence for its falsity)
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Old 17th February 2013, 11:15 PM   #3
RichardR
 
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Originally Posted by phildonnia View Post
Just my two cents:

The sentence is certainly very problematic. I don't know what is meant by an "attack on science", and so I would agree that this is ambiguous. I can't tell whether it materially supports some argument without seeing the rest of the context. But I think the intended meaning would be better expressed by replacing "attack on science" with "demonstration of ignorance concerning scientific facts and methods". (Since one does not scientifically conclude that "X might be true" from the absence of evidence for its falsity)
Thanks. Agreed it is ambiguous. But is it a fallacy?
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Old 18th February 2013, 12:06 AM   #4
Beelzebuddy
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Originally Posted by RichardR View Post
Thanks. Agreed it is ambiguous. But is it a fallacy?
No. At worst it's a pathetic fallacy - you're technically anthropomorphizing science, and it hates when people do that - but in context of the rest of the sentence it's pretty clear what you mean.
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Old 18th February 2013, 10:13 PM   #5
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That's it? 250 page views and only two opinions? No one else has a view?
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Old 21st February 2013, 03:15 PM   #6
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First, it's impossible to get an accurate view of whether or not there are any fallacies here, because it's ripped out of context. A random sentence in the most logical argument ever made would, removed from that argument, appear to have a huge number of fallacies.

The "ambiguity" in the word "science" is so pedantic that it's obvious the person you're debating is looking for a reason to dismiss the argument, rather than considering it logically.

The second ambiguity (over the word "safe") shows that the writer is dishonest. You can't claim that a quote contains a fallacy not included in the quote. That's just basic common sense.

I'd love to see evidence that there's any claim that someone can't prove a negative in the sentence mentioned. At best, it's making a specific accusation--presumably supported in that removed context. So this is a lie, at least until someone can demonstrate otherwise.

The non-sequitur may be there, but it's impossible to tell. It's clear, given the sentence, that it's either an opening or concluding statement to some argument. Presumably the connection would be made in that argument. It's simply dishonest to accuse someone utilizing a common and indeed necessary linguistic tool of a non-sequitur.

There simply is no contradiction in the sentence. It may be right or wrong, depending on the data, but the sentence is internally consistent.

The "Proof by Assertion" claim is dishonest as well. Again, it's quite clear that this is either an opening or closing statement intended to summarize a longer argument--to claim that this (again, common and necessary) linguistic tool is a fallacy is simply insane. And again, it demonstrates that the arguer is looking for a reason to dismiss this argument, rather than examining it rationally.

ETA: The arguer is actually committing the Fallacy Fallacy: Because the argument contains fallacies, it is therefore wrong. This is not true--even if there WERE fallacies in the argument (which has yet to be demonstrated) it would merely prove that the conclusions are UNSUPPORTED. There's a world of difference between "unsupported" and "wrong".

Last edited by Dinwar; 21st February 2013 at 03:17 PM.
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Old 22nd February 2013, 06:01 PM   #7
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I recommend just copying Dinwar's post to the person in question. It's spot on.

I would further stress that "you can't prove a negative" is not a logical fallacy, formal or otherwise. In deductive reasoning, you most definitely can prove negatives. For example, if p then not q; p therefore not q. With inductive reasoning, we run into the "there are no black swans" problem. You can disprove the conclusion by finding one black swan, but no number of times failing to find a black swan proves the statement. The latter is a problem with the scientific studies on this subject (see below). When we do safety testing, we never rule out the possibility that something is not safe. We can only gain greater and greater confidence that it's not safe (and perhaps weigh a shrinking risk of danger against other costs and benefits).

Having been in discussions on this same topic, I suspect there's been some goalpost moving. In my case the discussion began with someone's assertion that GMO foods are dangerous for humans to consume. I called for support for the assertion and was pointed to a statement by a non-scientific body that cited a handful of studies on mice and rats. The assertion had already morphed to the one given here in the added in text in brackets--not that GMO foods are dangerous but that they "might be" unsafe. (And there's also the problem of leaping to conclusions about humans from animal studies like these.)

Even ignoring the moved goalposts, that claim in context of these studies is itself dishonest. The studies were designed to look for evidence that the GMO food-fed group would have greater incidence of certain health problems than control groups, but they failed to find that. Yes it's true the studies didn't prove that GMO foods are safe; they only failed to show that they were unsafe. The statement that GMO foods may be unsafe doesn't require any support. That's always a possibility no matter how many studies are done that fail to show they are dangerous. So the claim that these studies point to the conclusion that GMO foods may be unsafe is misleading and dishonest.
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Old 22nd February 2013, 06:10 PM   #8
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Agreed with the above. I recommend:

http://www.fallacyfiles.org/taxonomy.html

In aiding in all your logical fallacy needs
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Old 23rd February 2013, 02:11 PM   #9
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Petty disputes about the number of fallacies in the sentence just seem to be a red-herring. Why not just clarify what the position is, and address the argument, however badly presented?
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