Absence of evidence IS evidence of absence

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What I find most interesting is that you've raised an example about scientists accepting a conclusion without evidence in a discussion that you started about how absence of evidence is sufficient to reject a conclusion.

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It successfully countered your statement that you brought up. That's what counts.

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Which is it, DNA? Are we to follow the model of scientists, who according to you, believe things without evidence, or your own example, who believes that an absence of evidence is sufficient to reject any proposition?

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Tsk tsk Crashfrog, back to stuffing words into my mouthBy the way, which part of the following do you state is false:**********************
For decades, scientists accepted that universal expansion was decelerating even though they had no PROOF (your improper term) that it was slowing nor did they know for sure that it was slowing.
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What I guess we'll never get you to see is that, on the question of the existence of things, a lack of evidence for the positive proposition (that the thing exists) is not evidence for the negative proposition. (There's qualifications to this that I'm willing to make, but they're not relevant here.)

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Aha. A concession, at least of sorts. Looks like even Crashfrog agrees that "absence of evidence is evidence of absence" is not necessarily one of the most fundamental logical fallacies, as someone attempted to mislabel it. (And considering that I have made it abundantly clear that my position is NOT that absence of evidence is PROOF of absence,...)

The part I believe to be false about this is where you present this as a universal conclusion of scientists.The truth is, scientists believed that a decelerating expansion was predicted by their theories. That's a big difference between believing that it's really happening. Though I suspect that's a distinction that's lost on you. No, it is fallacious, because you can't use it to make conclusions.There's no conclusion you can draw from a lack of evidence. That's why we have the word "inconclusive", which you seem to avoid.Now you tell me - what do you think you can prove, or deduct from, inconclusiveness?

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Which is it, DNA? Are we to follow the model of scientists, who according to you, believe things without evidence, or your own example, who believes that an absence of evidence is sufficient to reject any proposition?

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Tsk tsk Crashfrog, back to stuffing words into my mouth

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By the way, which part of the following do you state is false:

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For decades, scientists accepted that universal expansion was decelerating even though they had no PROOF (your improper term) that it was slowing nor did they know for sure that it was slowing.
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The part I believe to be false about this is where you present this as a universal conclusion of scientists.

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You're dodging the actual question I see. Of course you can't simply answer my question honestly because your doing so would support my position and do harm to yours.But of course we all know that what I said is true - that for decades scientists accepted that universal expansion was decelerating even though they had no PROOF (your improper term) nor did they know for sure that it was slowing.So your childish word games - intentional manipulation of words with the goal of making it appear that I alone held a certain position, which you distorted, stuffed back in my mouth, and then implied was dubious or erroneous - fails. What I said was and is correct: I know it, you know it, and everyone else familiar with the topic knows it.

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The truth is, scientists believed that a decelerating expansion was predicted by their theories. That's a big difference between believing that it's really happening.

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Quite irrelevant regardless whether that is correct or not. I am still correct: For decades, scientists accepted that universal expansion was decelerating even though they had no PROOF (your improper term) that it was slowing nor did they know for sure that it was slowing.Here's the context.

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I find it rather puzzling, really, that you're so willing to reach conclusions that you admit have no proof.

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Really? Then you must not be familiar with science.

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First, have you ever heard that "proof is for mathematics and alcohol". Any idea why people say that???

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Second, there are "tons" of conclusions scientists have reached without having proof (obviously) and without knowing for sure that their position was correct. One example that pops to mind immediately....for decades scientists accepted as fact that Universal expansion was slowing over time, yet they had no proof that it was. But did they know for sure that it was? Nope. In fact, somewhere around 1998 multiple evidences by two teams (at least one of which had been studying Type IA supernovae) indicated that universal expansion is doing quite the opposite: accelerating. Another that comes quickly to mind is the dispute over whale evolution: have whales descended from a mesonychian ancestor or an artiodactyl? Back in 1999 (if not still) both sides claimed to have enough evidence to show their position correct and the opposing side's wrong: note that at most, only one of those opposing groups of scientists can be correct: the other team must be wrong.

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If science actually had to hold off drawing conclusions until proof was discovered, as is in line with your comment, then science would come to a practical standstill.

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[This message has been edited by DNAunion, 11-08-2003]

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That I cannot find my car keys on my kitchen table is evidence that they are absent from the kitchen table. It isn't evidence (trust me!) that they aren't in the kitchen, they're probably on the microwave. The absence only becomes meaningful when the whole picture is being looked at.

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I disagree. Looking for them in the kitchen - on the table - and not finding them there is evidence that they are not in the kitchen. It isn't proof, and the evidence may even point towards the wrong conclusion (they very well may be on the microwave), but it is one piece of evidence that supports the position that the keys are not in the kitchen.

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It is specific evidence that they are not on the kitchen table, not that they aren't in the kitchen at all.

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I still disagree (and yes I read your whole post before replying). Looking for them in the kitchen — on the table — and not finding them is one piece of evidence that supports the position that they are not in the kitchen. More below.

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So in the case that involves the entire kitchen where only one part has been searched, absence of evidence isn't evidence of absence. It is evidence of absence as regards the kitchen table, however.

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Yep, and it is also one piece of evidence that supports the position that they are not in the kitchen.

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The keys are either in the kitchen, or they aren't, they are either 100% there, or they are 100% not there. Assume there are five locations in the kitchen where they might be, the table, the drawer, on the microwave, on the shelf, or in my pocket. In eliminating the table, the keys are STILL either 100% there [I assume you mean in the kitchen], or 100% not there [I assume you mean not in the kitchen]. The probability of their existence [sic] hasn't dropped to 80%. It is a binary off/on proposition. Therefore, the fact that that they are not on the table hasn't allowed you to make any tentative conclusions as regards the likelihood that the keys are in the drawer, on the microwave, on the shelf, or in my pocket.

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I disagree. According to your above reasoning, we could search the table, and the drawer, and the microwave, and the shelf, all without finding the keys, yet we would still have NO EVIDENCE WHATSOEVER that they weren’t in the kitchen. In fact, by your reasoning, we would have NO EVIDENCE WHATSOEVER that the keys weren’t in the kitchen until were performed a COMPLETE AND EXHAUSTIVE search and failed. But by that point we’d have PROOF of absence in the kitchen. So you too are equating mere EVIDENCE with much stronger terms like PROOF or INDISPUTABLE FACT, you're just doing so implicitly. Thus, you are not addressing the position I put forward.[This message has been edited by DNAunion, 11-08-2003]

This is getting silly!DNA has stated very, very clearly that absence of evidence is "evidence" not "proof". And it clearly is evidence.All of us, (well maybe not the mathematician ) will decide after enough work that continued absence of evidence IS "proof" of absence. How soon we make that leap will depend on what the totallity of evidence is like.We have not drained Loch Ness to look for the wee beastie have we? However, a variety of reasoning on ecology and the absence of any good evidence leads most of us to conclude that the laddie isn't home doesn't it? We may well accept that it isn't perfect "proof" but we act as if it is. We will not bet our life savings on him being there. We don't finance yet another search. We take the existing evidence including the fruitless searchs as input (i.e., evidence) that he just isn't home. (which I'm sad about actually).Enough already! geez

.[This message has been edited by mark24, 11-09-2003]

No, I'm answering it. That you percieve my answer as a dodge is indicative that you simply don't understand the distinction I'm trying to draw. Perhaps if you concentrated less on acting indignant when you think I'm slighting you and more on the actual substance of my arguments, we might get somewhere. Honestly, for a poster who inserts so much of themselves into the discussion, I've never seen anybody with such a thin skin.The distinction you appear incapable of drawing is the difference between the things we think we know because our models predict them, and the things we know we know because the evidence sugests them. That's what I don't like about your question - it assumes that generalization from evidence and prediction from model are exactly the same, when they plainly are not. The difference of course is in confidence. Again you're mischaracterizing the situation. What they accepted was a prediction based on a model, not a conclusion based on evidence, or no evidence.Is there even a point in talking to you, by the way? Since you apparently can't tell the difference between logic and word games? (Why is it that the only people who ever accuse me of playing games are the people who are most guilty of doing it themselves?)

The problem isn't what is proof and what is not. The problem is that DNA is using this thread to support his actions in another thread, where he equivocated one piece of evidence with enough evidence to draw a conclusion, namely one of fine-tuning. It's this action that he simply won't own up to, or even respond to. Hardly good-faith actions, in my view, but there you are.

I agree with you on the other thread Crash. Misuse of this idea doesn't in the other thread doesn't mean it is wrong though.However, I also agree with you on the distinction you are making in your previous post. Saying absence of evidence *is* evidence of absence isn't really saying all that much really.It doesn't say it is very good evidence. That will depend on the details of the specific case.

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I disagree. According to your above reasoning, we could search the table, and the drawer, and the microwave, and the shelf, all without finding the keys, yet we would still have NO EVIDENCE WHATSOEVER that they werent in the kitchen. In fact, by your reasoning, we would have NO EVIDENCE WHATSOEVER that the keys werent in the kitchen until were performed a COMPLETE AND EXHAUSTIVE search and failed. But by that point wed have PROOF of absence in the kitchen. So you too are equating mere EVIDENCE with much stronger terms like PROOF or INDISPUTABLE FACT, you're just doing so implicitly. Thus, you are not addressing the position I put forward.

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So, we've done a complete and exhaustive search of not only this universe, but all possible universes?I'll put it this way: two weeks ago, I lost my keys. I knew they had to be somewhere in my place, but I couldn't find them. I checked the kitchen table. I checked the ironing board, where I occasionally set stuff. I scoured my purse in and out. I checked the dresser. I checked all of the end tables in the living room. I pretty much gave up, and was going to get a new set. Should I have concluded that they were not in the place (I didn't just search a tiny fraction, but most of the apartment)?A week later, they turned up in a coat pocket.It was an early prediction of Conway's Game of Life that there would be no infinitely expansive patterns ("puffers"). None turned up during Conway's work. Should he have concluded that there were none?There were.The key here is the percentage of the possibilities that you look at. If your sample size is "all possible universes" or even just "this universe", the percentage you're going to look at is virtually zero; thus, an absence of evidence argument is effectively worthless.------------------
"Illuminant light,
illuminate me."

Hang on. What you are asking is: "Is it proof?"We all agree that it is not proof. Therefore a conclusion drawn on absence of evidence could very well be wrong.Is a negative finding evidence for anything at all? Yea, I think we agree on that. Can you always extrapolate from a small set of negative results? Sure you can. Will you be right some of the time? Yes. Will you be wrong some of the time? Yes.The question is: "When can we decide to start using absence of evidence for *good* (ie. useful) evidence of absence?" Can I answer in general? No.As far as the universe case goes, we haven't done much of a search, as you say, and we don't know enough to make other judegements about the likelyhood of what we are looking for. The situation is simply not decideable yet.

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I disagree. According to your above reasoning, we could search the table, and the drawer, and the microwave, and the shelf, all without finding the keys, yet we would still have NO EVIDENCE WHATSOEVER that they werent in the kitchen. In fact, by your reasoning, we would have NO EVIDENCE WHATSOEVER that the keys werent in the kitchen until were performed a COMPLETE AND EXHAUSTIVE search and failed. But by that point wed have PROOF of absence in the kitchen. So you too are equating mere EVIDENCE with much stronger terms like PROOF or INDISPUTABLE FACT, you're just doing so implicitly. Thus, you are not addressing the position I put forward.

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So, we've done a complete and exhaustive search of not only this universe, but all possible universes?

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Nope, which is why we don’t have PROOF of nonexistence.

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It was an early prediction of Conway's Game of Life that there would be no infinitely expansive patterns ("puffers"). None turned up during Conway's work. Should he have concluded that there were none?

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There were.

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Yeah, so? Scientists have drawn many conclusions that turned out to be wrong; science doesn’t require PROOF, despite Crashfrog’s assertion.And quite frankly, I just can't see how Crashfrog (or anyone else) can honestly say

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That's why we have the word "inconclusive", which you seem to avoid.

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I’ve been talking about we don’t know which is true, it’s not proof, it could be wrong, tentative conclusion, and other similar things throughout this thread and the other. My middle name is inconclusive! :-)I'm a fence sitter in general (until sufficient evidence has been supplied to convince me that one position is correct). Now, when someone wonders too far from the fence in a certain direction without having solid evidence to support such a deviation from "inconclusive", I try to pull them back to the fence. Perhaps you guys are misinterpreting the pull from the opposite direction as my being way over on the other side of the fence.[This message has been edited by DNAunion, 11-09-2003]

So, then, you agree that there's no way to argue that the universe is fine-tuned for life?

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So, then, you agree that there's no way to argue that the universe is fine-tuned for life?

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I don't agree with your logic.(1) Position X's status being inconclusive
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(2) There being no way to argue for position X
are not the same thing.In fact, if something IS CONCLUSIVE, then how could one legitimately argue about it?In fact, it is basically only the things that ARE INCONCLUSIVE that can be argued for or against.[This message has been edited by DNAunion, 11-09-2003]

But in fact (2) is exactly what (1) means. When something is inconclusive, it means that one is unable to reach a conclusion about it. How could you argue, therefore, if you cannot conclude? This is simply foolish. An inconclusive proposition cannot be argued because it's impossible to determine which side of the proposition is correct. Just because it's possible to draw a conclusion doesn't mean it's not possible to argue about it.