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A discussion on weighing up two sides of an argument

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  • #46
    Originally posted by Wickerman View Post

    Years back, like in the late 90's, I was on a forum with a NASA scientist. The groups ended up on this topic of what is Theory and what is Speculation, and how we arrive at 'truth'.

    See if I can remember how it was explained.
    - A Theory is one interpretation of a set of facts.
    - One fact does not make a Theory.
    - Each fact must be provable.
    - There can be many interpretations of the same group of facts, but only one interpretation (the Theory) is the correct one.
    - If you have 10 facts (an arbitrary number) on any subject, the resultant interpretation is a Theory. However..
    - If one of those facts turns out to be incorrect, the resultant Theory is now mere Speculation.
    - It only takes one false fact to degrade a Theory into Speculation.

    So, where we read of theorists who have a Jack the Ripper suspect, just be aware you need evidence comprised of a set of facts. And each fact must be provable, for you to have a genuine Theory, otherwise what you have is just fantasy (Speculation).

    Hi Wickerman,

    That would have been an interesting conversation. I have suggested that research be viewed as 3 separate "spaces", if you will. Theoretical space, which is a collection of truth statements, which can be subjected to evaluation via the rules of logic. A theory is a collection of truth statements. For a theory to be "true", all statements must evaluate to true. If one is shown to be false, the theory is false, although it may not be fatal to all other statements, and only requires a revision. There is also methods space (the things we do, so what the police did in their searches, or how an inquest was held, for example) and data space (what resulted from what was done; what evidence did they find in their search, what did people testify to, etc).

    While that set up is easy with experiments, where things set in methods space (how you set up the experiment) lead to values in data space (what you do determines what you find) and then one compares what was observed with what was predicted within theoretical space. If the observed values do not match the predicted values, that creates the paradox allowing experimental observations to falsify the truth statements where one states the observed values will equal the predicted value. Since they don't, that's false, setting up a chain of disconfirmation in theoretical space.

    With JtR, the methods are less controlled situations, and would include things like what a witness was doing when they observed a situation, which they later testify to in the context of the inquest or interview.

    This shows up a lot in discussions, where people wonder if the witness was paying sufficient attention to identify the person (i.e. Lawende's identification of Eddowes via her clothes). If that's a poor method of identification (which of course it is), then does the data (him deciding the clothes are similar and testifying as such) matching the predicted value (if he saw them he has a chance of recognizing them -> he may recognize her clothes) and that last statement matches his testimony. The problem, of course, is that there are all sorts of theoretical bits that come into play, such as failures of memory, he might have seen her but not recognized her clothes (that didn't happen of course), or he might not have seen her and misidentified her clothes as the ones he saw (which also fits the data).

    It is always a theoretical claim that "this data is wrong", because the data is what the data is, it's the explanation that is being questioned. If someone argues "Lawende's statement is invalid" they don't mean his words are invalid, they are adding in theoretical space "but he misidentified Eddowes clothes as the clothes he saw but which were of another person", which is just a complicated way of saying Lawende didn't see Eddowes. But it puts statements into theoretical space.

    Theoretical space, however, has to tie into observations. So, to make that claim, one needs to tie it to data somehow. Generally, the Lawende identification type thing starts to point to "similarity of dress among Victorian women of the day in that area", and other things to point out that misidentification is highly probable. While it doesn't prove misidentification hadn't happened in this instance, it does question whether the data arises from actual recognition.

    Speculation is just the filling in of theoretical space without ties to data space (i.e. we don't have evidence for these statements). Generally, theoretical space is an attempt to explain the observed, and we expand the observations by investigation. Speculation is just the filling in of theoretical space with statements without ties to data space. That can be useful because it may suggest what needs to be done for an investigation, and if the data space fills up with values that those speculative statements made, they become supported and integrated into the overall collection of statements (into theory), but until they do, they are considered weak points and can be removed at will and replaced with any set of speculations that do not conflict with observed data.

    To compare various "speculation fills", then one can use things like "Your speculation involves very rare events, mine involves highly common events", in which case the latter is considered the better option (it is logically more sound to go with the more common events until data space indicates those events did not happen). Also, explanations that "fill in the gaps" with the fewest number of unsupported statements are better, simply because unsupported claims are to be avoided.

    I guess it's a similar idea, that theoretical statements are ones that have at least some ties to data space, and speculations are statements without ties to direct observations.

    - Jeff


    • #47
      Where did most people cease reading that,if they started in the first place?

      that that is is that that is not is not is it
      My name is Dave. You cannot reach me through Debs email account


      • #48
        Originally posted by DJA View Post

        I meant "fact" in the circumstances we are discussing.
        Ah, ok, I thought it might be 'game time'. As if my interpretation of what is factual might be different than what is given when we Google it - no difference.

        Not really.Quite unpopular here.
        I think you mean the reception of a cover-up theory is unpopular here, yes it would appear so. It's my view that many posters see it for what it is.

        What I meant was the originators of a 'who was JtR' theory here on Casebook seem to want to include 'the cover-up', - can you think of some-one's who doesn't?

        Certainly not. I respect your views and usually agree with them.In fact most of your "likes" are mine.
        Well, thankyou much for the vote of confidence, though I must admit I don't look at anyone's 'like' box, least of all my own.

        Regards, Jon S.


        • #49
          Originally posted by DJA View Post
          Where did most people cease reading that,if they started in the first place?

          that that is is that that is not is not is it
          I had a crack at it, I really did.
          Thems the Vagaries.....


          • #50
            The Hammster's piece or my line that requires punctuation which is much more fun?
            My name is Dave. You cannot reach me through Debs email account


            • #51
              Originally posted by DJA View Post
              The Hammster's piece or my line that requires punctuation which is much more fun?
              Sorry Dave, after Jeff's marathon post, I was all funned out.
              Thems the Vagaries.....


              • #52
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                My name is Dave. You cannot reach me through Debs email account


                • #53
                  I fear we may have derailed this thread...
                  Thems the Vagaries.....


                  • #54
                    The Fugitive 20th Anniversary | Bus Train Crash | Warner Bros. Entertainment - YouTube
                    My name is Dave. You cannot reach me through Debs email account


                    • #55

                      Ok, it appears that I've jumped too far into the topic for it to make sense. And, due to the nature of philosophical discussions, they often result in lengthy posts.

                      Here's sort of the crux of what I'm trying to get at.

                      Logic, or reason, operates on proving things by indisputable combinations of truth statements.

                      For example, given the following:

                      All swans are white.
                      Yesterday I saw a swan.

                      If both of those are true, we can create the new statement:

                      The swan I saw yesterday was white.

                      That has to be true beyond all doubt provided the first two statements are also true.

                      The problem we face, is that we never have statements of the "All swans are white", we have statements like "Most swans are white." And, given there are black swans, we know that first statement is not true (some swans are black).

                      That means, while both of these statements can be true:

                      Most swans are white.
                      Yesterday I saw a swan.

                      We cannot say that beyond all doubt "The swan I saw yesterday was white" because the first premise is not of the "all swans" construction.
                      Through the application of pure reason, it doesn't matter how rare non-white swans might be. There could be only 1 in a billion swans that are not white, and we still cannot, through the application of the rules of pure logic and reason, draw that conclusion beyond all doubt. But can we get to "beyond reasonable doubt"?

                      What if we knew that 99.9999999% of all swans were white (1 in a billion), and that I saw a swan yesterday. With no other information to work with, what would we consider the weight of evidence towards the conclusion?

                      So in this situation (call it Situation Minimal data), Rationally, we should consider that the swan I saw was, in all probability, one of the white ones. It's not proven, but that would be the safe bet which would satisfy "beyond reasonable doubt" given the information we have.

                      What if we add more information to work with (Situation more data)? Can we change that level of doubt? (given it's not 100%, it should, rationally, be open to change, either increasing or decreasing that level of confidence).

                      What sort of information might change our view on that? Well, if you had evidence that I was in a location known to have those extremely rare swans yesterday, and you knew I had some sort of interest in swans, or birds in general, or even just animals in general, then now you have new information, still not sufficient to meet the strict rules of pure logic and reasoning, but information that you could argue increases the likelihood I would have gone to specifically see that black swan. You don't know for sure I did go, but you would have grounds (based upon knowledge of how humans make choices) to argue there is a high probability that I would take the opportunity to satisfy my interest in animals by going to view an extremely rare example.

                      So, now, despite how rare our black swans may be, we then have an argument that could very well lead to the conclusion that it is more likely that the swan I saw was, in fact, not white. But it's still not proven 100%, but this would probably at least meet the criterion of reasonable doubt.

                      While none of it leads to the kind of "proof" in the absolute sense, reasoning based upon statements of the "Most X are Y" formulations can still follow rational rules of reasoning, with the end result not being of the "beyond all doubt" conclusion (which we could do if All swans were white) but it shows how probabilistic premises (Most swans are white) can be used rationally to weigh two possible conclusions despite the two possible conclusions ever being ruled out entirely beyond all doubt).

                      What is important to notice, however, is that to shift the weight of evidence from our conclusion of a white swan in the "situation minimal" example towards our opposite conclusion of a black swan in "situation more data", requires we have more data, not simply emphasizing that 1 in a billion swans are black. That emphasis alone is not an argument, it's just restating why the evidence is in favour of the safer conclusion in the first place.

                      None of the above limits what arguments we can consider, or put forth, or debate over. What it does, however, is focus us as to what sort of evidence we might need to provide when we're suggesting that a rare option is the one to consider as the most likely conclusion. We need to find and present evidence that shifts the weight of evidence towards to the more improbable side of that "Most X and Y" side of the equation. We can't just say "But not all X are Y therefore the answer is not Y despite X being the case. If most X are Y, then the safe conclusion is Y, unless something evidential comes into play that shifts the probability that we are, in fact, dealing with an example of the more unlikely situation of "not Y".

                      - Jeff

                      Oh, by the way, black swans are pretty common in New Zealand and Australia. I had never seen or even heard of one before I moved here, and often wondered why examples in logic lectures often used things like "All swans are white" in their examples. It was never actually pointed out that this starting premise was wrong, so the first time I saw one I was pretty surprised. I've called them "logic swans" ever since, but that, perhaps, is a level of geek too far.
                      Last edited by JeffHamm; 04-04-2021, 09:49 PM.


                      • #56
                        Ok, why I think the above post contains some useful points with respect to JtR type discussions.

                        First, beyond the trivial, in a murder case, historical or current, we are never in the situation where we have starting premises of the "all X are Y" type. Rather, we have statements of the "some X are Y", where some might be replaced with "most" or some other description indicating a probability. Things like "the vast majority of murders are committed by someone known to the victim". But that, of course, means that not all murders are committed by someone known to the victim.

                        We see this come up in suspect focused debates, where if a known link can be made between the suspect and the victim this is put forth as positive evidence for the case. Barnett comes to mind for example (just introducing a concrete example, with no desire to debate the merits of any individual case here, there are threads for that). Despite that, I'm going to just stick with Barnet in my example here, but the focus in on where I think such a debate would be most fruitful in terms of getting us somewhere.

                        So yes, as a starting point, that would be a fair argument, there is often a link between a victim and their murderer, and Barnet has such a link with the last victim. Other examples, such as Kemper, can even be pointed to illustrating that very point. For those arguing against, they need to bring arguments as to why, in this particular case, they believe the JtR cases are more likely to be an example of either the less common "stranger murder" (and so arguing against any theory that posits a relationship) or, the more focused situation of bringing in evidence against the specific link between Barnet and the murders. But it is not sufficient to just say "but some murders do not have that link.", that's just restating the "some X are Y" in a reverse statement of "some X are not Y", and in this case the weight is in favour of the first formulation (more are related than that not related).

                        Now, for other aspects of a discussion, we get into more subjective areas of the weight we might assign to that "some X are Y" type starting point. I might argue "it is highly likely that X are Y", but if I can't show some objective data to support that indeed "most X are Y", the counter argument should focus on my claim of "high probability". One could simply say "well, in your opinion most X are Y, but unless you can demonstrate that is the case, it could be that few X are Y".

                        But we now reach a point where neither side can claim they are right because neither side is presenting evidence of the underlying probability X are Y. What it does, though, is focus us both on what evidence we need to be looking for. Because, if we are both rational, then knowing the relative probabilities between "X are Y" and "X are not Y", would then lead us both to agreement. Rationally, we should end up both coming to a common conclusion once that weighting is determined.

                        Of course, if upon determining that weighting we see that both conclusions still have a high support (let's say half of X are Y and half are not Y), then we we would rationally have to agree that "hmmm, it appears knowing X is not the important piece of the puzzle we thought it was", again leaving us without a rational conclusion to choose in the bigger topic.

                        None of this limits what we can or cannot put forward for consideration. Rather, knowing how rational arguments "work" when dealing with probabilistic premises can make us focus on how to bolster our case, and also how to recognize when someone has pointed out where our case is weak and needs work. We always have in a murder case probabilistic premises, and even a match with DNA evidence is always testified as having a probability of being "not the suspect", it's just so very small we reject it as unreasonable to consider.

                        And, of course, it's also totally fine if people want to stick with their idea, despite it being the case that their idea falls on the less probable side of the final evaluations. By keeping in mind how rational decisions are made using this type of information, it can guide people to look for evidence that would end up changing the balance (such as finding out I was interested in rare birds, and was in the area of the 1 in a billion black swan example I used in the post above; combine that with information about how people will do things that reflect their interests, and suddenly we're building a case that makes it more and more reasonable to suggest the swan I saw was indeed a rare black swan).

                        The more and more specific a case gets, meaning the more and more suspect focused it gets, the more it becomes important to have that sort of evidence, that only has a high probability of leading to that rare case because there are more people that are not Barnet than are Barnet, so the probability (without any other information to guide us) is that JtR was not Barnet (again, only used as an example; put anything other name in there if Barnet is your chosen favorite suspect. I'm not suspect focused myself, but if I were, I would have used my own personal top choice).

                        Anyway, as I say, nothing about understanding how rational argument "works" in any way limits the topics one can discuss. But I believe it can greatly benefit everyone to take a moment to consider it because it will aid one in choosing what aspects of their case need the most focus of improvement.

                        The case isn't solved, after all, so any and all solutions could be wrong. So finding how to rationally tip the balance towards or away from a given solution is a useful thing to know. It's about knowing the tool, not limiting what what builds with them, but how to build that thing more easily and creating a sturdier item.

                        - Jeff


                        • #57
                          Hmmm, I suppose there is one other aspect of debate and discussion that I should mention.

                          Rational approaches to debate and argumentation, which is what I've been focusing on above, is not the only approach available. The underlying goal, however, of reason is to get to the "truth." This is why pure reason focuses on those "All X are Y" ideals, because from those situations one can absolutely derive a true statement. Again, with the swans, if it were true that All swans are white, and it were true that I saw a swan yesterday, I never have to tell you that the swan I saw was white. You do not need my statement to that effect to prove the swan I saw was white. It had to be, purely through logical reasoning.

                          Those "some swans are white" type constructions don't allow for absolute truth to be derived at purely through logical reasoning, and because rare events do happen sometimes, pure reason throws a hissy fit and says we can't get to pure truth. The approach about how to deal with those is uncomfortable to the extremist of pure reason because of that - the objective can never be reached, similar to Achilles and the tortoise. However, just as calculus solved that paradox, philosophers have worked on rational rules for probabilistic premises in a similar way (while one cannot reach pure truth, one can try and estimate which limit of true/false is being approached by the asymptote).

                          In contrast, debates and discussion can introduce techniques from the school of sophistry. The goal of sophistry in a debate is not to discover truth, but rather only to persuade others to one's way of thinking. Eloquence, for example, is a technique emphasized by sophistry. See, the truth value of a statement doesn't change just because it is phrased awkwardly. It might not be clear, or easy to understand, but that doesn't necessarily make it any less true (or false, if you prefer). Granted, poorly phrased statements often introduce unintended meanings, which in turn would impact the truth value, but it does not have to. Sophistry emphasizes presentation techniques to win over listeners without adding any truth value to the statements. As such, in a debate where the rational argument is true, but presented awkwardly might fare more poorly by an elegant, but false, counter argument.

                          While eloquence is beneficial to the presentation, as it makes it easier to evaluate the truth values, it can also be used as a technique to persuade listeners to false conclusions.

                          Other sophistry techniques involve the use of pejorative language, particularly directed at the other speaker rather than their arguments per se. The idea is that if one can make the listeners view the other speaker more poorly, then the reasoning behind their arguments will be ignored. (Pointing out spelling or grammatical mistakes, for example, is a great distraction from the truth content of a statement) Again, the goal of sophistry is not to persuade by the strength of one's arguments, but rather to persuade through techniques of speech that do not contain or contribute to the truth value of what is said.

                          I am not a proponent of this form of counter-argument, although I recognize that clarity of presentation is beneficial I only recognize that provided it is the truth aspect of the statement that is clarified. When eloquence is used to mask a false statement as true, then it because a bad thing, in my view.

                          However, those of the sophistry school of debate do not agree with that last comment, because sophistry has a different set of "winning conditions", if you will. The objective is not to be true, but to convince, regardless of the truth.

                          So, while it is my opinion that sophistry should be avoided, I'm not espousing that the boards prohibit someone whose approach is of the sophistry school of debate. Indeed, I know for a fact I have entered into sophistry styles of debating on occasion, and while it can be emotionally satisfying, I also recognize it does not advance our progress in understanding what happened in 1888. Only fools would disagree with me there! (That, for example, is sophistry).

                          - Jeff

                          P.S. And to the great relief of what I suspect is not an entirely small number, I think I'm done.

                          P.P.S. I've been wrong before about that though.


                          • #58
                            Most swans hereabouts are black.Last white swan I saw was in the Melbourne Zoo 40 years ago.

                            We learnt most of this soon after reading "John and Betty" (and Fluff and Scottie).

                            Not really.

                            Crikey though,keep this thread running.Winter is not far away.
                            My name is Dave. You cannot reach me through Debs email account


                            • #59
                              Originally posted by Al Bundy's Eyes View Post
                              I fear we may have derailed this thread...
                              Meh,it's back
                              My name is Dave. You cannot reach me through Debs email account


                              • #60
                                Originally posted by DJA View Post

                                Meh,it's back
                                Hi DJA,

                                You do realize that you are not obliged to read a thread you're not interested in.

                                - Jeff

                                P.S. Yes, as I noted, black swans are common in Australia and New Zealand. Quite possibly elsewhere as well, but I had never even heard of them when I lived in Canada.