Register | Sign In


Understanding through Discussion


EvC Forum active members: 65 (9162 total)
2 online now:
Newest Member: popoi
Post Volume: Total: 915,817 Year: 3,074/9,624 Month: 919/1,588 Week: 102/223 Day: 13/17 Hour: 0/0


Thread  Details

Email This Thread
Newer Topic | Older Topic
  
Author Topic:   Probability-based arguments
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 1 of 27 (485073)
10-04-2008 9:13 PM


I am new to EvC Forum, but not new to the debate. I have an idea for an interesting discussion that, in my opinion, is deserving from both viewpoints.
I have seen many arguments which invoke some form of probabilistic reasoning to back a viewpoint.
Example 1: This takes place over tens of millions of years, and is therefore possible (implying a number of trials over which random mutations may operate)
Example 2: The odds of a jawless fish becoming "jawed", with fully operating nerves, etc., are found to be 1:10^some big number, and is therefore not possible
Each of these seem reasonable on the surface, and they are repeated by camp residents over and over. However, there are a number of basic flaws.
There is a vast difference in this discussion between our ability to model something _a priori_, based on first principles (thinking about a six-sided die), and our ability to model a process _a posterior_, based on observations of actual data, preferable of several different experiments (repeatedly rolling that die). Is the die loaded? Does it prefer certain long-term arrangements (is it non-random?)
Since with the evolutionary discussion points, we have, at best, inferential supposition, neither modeling techniques is even marginally well founded. We have some localized data, but certainly not enough to calculate something as momentous as whether or not life could evolve spontaneously.
It would seem then, that we should examine whether any of the probabilistic arguments are even valid at all, mathematically speaking. This is much more difficult than almost all folks consider.
What say ye, people of the discussion?

Replies to this message:
 Message 3 by Blue Jay, posted 10-05-2008 9:13 AM boysherpa has replied
 Message 4 by Modulous, posted 10-05-2008 9:19 AM boysherpa has replied
 Message 5 by Agobot, posted 10-05-2008 10:10 AM boysherpa has replied
 Message 16 by PaulK, posted 10-06-2008 7:23 AM boysherpa has not replied

  
Admin
Director
Posts: 12998
From: EvC Forum
Joined: 06-14-2002
Member Rating: 2.3


Message 2 of 27 (485110)
10-05-2008 8:13 AM


Thread moved here from the Proposed New Topics forum.

  
Blue Jay
Member (Idle past 2698 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 3 of 27 (485115)
10-05-2008 9:13 AM
Reply to: Message 1 by boysherpa
10-04-2008 9:13 PM


Hi, Boysherpa.
Welcome to EvC!
boysherpa writes:
There is a vast difference in this discussion between our ability to model something _a priori_, based on first principles (thinking about a six-sided die), and our ability to model a process _a posterior_, based on observations of actual data, preferable of several different experiments (repeatedly rolling that die).
Modeling is extremely important to science. Models allow you to manipulate variables in a simplified manner that you couldn't manipulate in nature, and they give you a baseline to which you can compare your actual data.
Science uses both techniques you mention above: it starts with an abstract model, then designs experiments to specifically test that model in an unstudied situation. Without the model, we would essentially just be wandering around hoping we found interesting data. It makes much more sense to put up a model to test, because then we just have to look for specific information that would support or reject our model.
Like it or not, this method has led to many discoveries of previously unknown information. There simply isn't a better way to investigate questions about the physical world.
boysherpa writes:
It would seem then, that we should examine whether any of the probabilistic arguments are even valid at all, mathematically speaking. This is much more difficult than almost all folks consider
What say ye, people of the discussion?
If you can think of a better way, let us know.
The simple fact of life is that you really can't get a completely reliable, 100% answer about anything. You could directly observe several thousand crows in nature, and still not be able to prove that all crows are black. So, you have to stipulate that crows are typically black, and leave room open for an albino crow to pop up every now and again.
The failure to reach absolute certainty is not grounds for dismissing the argument. To do so is to say that, if we can't know everyting, we can't know anything.
-----
P.S. You can make quote boxes and formatting by following the "dBCodes" help link on the left-hand column in the "Reply to Message" screen. Press the "Peek" button at the bottom of a message to see the codes used in that messsage.
Have fun at EvC!

-Bluejay
Darwin loves you.

This message is a reply to:
 Message 1 by boysherpa, posted 10-04-2008 9:13 PM boysherpa has replied

Replies to this message:
 Message 7 by boysherpa, posted 10-05-2008 11:14 AM Blue Jay has replied

  
Modulous
Member
Posts: 7801
From: Manchester, UK
Joined: 05-01-2005


Message 4 of 27 (485117)
10-05-2008 9:19 AM
Reply to: Message 1 by boysherpa
10-04-2008 9:13 PM


Welcome to EvC,
Example 1: This takes place over tens of millions of years, and is therefore possible (implying a number of trials over which random mutations may operate)
Since with the evolutionary discussion points, we have, at best, inferential supposition, neither modeling techniques is even marginally well founded.
Are you trying to suggest that natural selection does not have many decades of foundation work. Have you ever heard of the likes of John Maynard Smith and those that followed him?
There are two models
1: Differential reproductive success in a population of beings with heredity leads to individual members of the population on average, becoming better and better adapted to their environment. In the case of biological entities, the means of heredity and the expression thereof is supported by the following...15,000 pages later...and that's how it works.
2: The probability of an event that nobody in the world has ever postulated as a sensible explanation is so very improbable it almost certainly never happened that way.
It seems unusual that you would even suggest that the two models are on the same footing.
Edited by Modulous, : No reason given.

This message is a reply to:
 Message 1 by boysherpa, posted 10-04-2008 9:13 PM boysherpa has replied

Replies to this message:
 Message 6 by boysherpa, posted 10-05-2008 10:47 AM Modulous has replied

  
Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 5 of 27 (485120)
10-05-2008 10:10 AM
Reply to: Message 1 by boysherpa
10-04-2008 9:13 PM


I take it you mean Evolution is true but there seems to be something missing to explain the fast-rate of certain mutations needed for the morphology of living organisms that we've observed.
That's a question that has boggled my mind as well, and in IMHO the environment must have been exerting pressure in a way, so that particluar "directed" mutations would be more prevalent. Of course I could be wrong, this is just my non professional conclusion based on my personal observations.

This message is a reply to:
 Message 1 by boysherpa, posted 10-04-2008 9:13 PM boysherpa has replied

Replies to this message:
 Message 11 by boysherpa, posted 10-05-2008 12:09 PM Agobot has replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 6 of 27 (485121)
10-05-2008 10:47 AM
Reply to: Message 4 by Modulous
10-05-2008 9:19 AM


A good point, modulous
Thanks for the welcome!
I am not I explained my question well enough, but you raise a great point of explanation.
Natural selection and selective breeding are well-documented and explained localized operating mechanisms, both being external operators influencing differential reproductive success. But, these topics are not central to what I was discussing, since they are always observed for a specific species in a specific situation.
Rather, a closer situation would be to monitor, say, several species' morphological mutation rate in response to specific conditions, and attempting to infer a global "probability" (in time terms as well) that such a "successful" adaptation can occur for a generic species. This will prove difficult, but is what is required for the question at hand.
Showing that an adaptation has occurred reveals nothing about its mathematically probability of occurrence except that it is nonzero (not even that it is nonzero, I suppose - God could have created it in violation of probability laws, but that is not what I seek). This is the core of the question.

This message is a reply to:
 Message 4 by Modulous, posted 10-05-2008 9:19 AM Modulous has replied

Replies to this message:
 Message 8 by Modulous, posted 10-05-2008 11:35 AM boysherpa has replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 7 of 27 (485122)
10-05-2008 11:14 AM
Reply to: Message 3 by Blue Jay
10-05-2008 9:13 AM


Modeling is indeed the key
Thanks Bluejay!
I think you have hit on the key points of my question. I am well-versed in modeling, and think that my question involves the apparent lack of a good model or even awareness of modeling rules in the use of probabilistic statements. (BTW - thanks for the dBCodes tip)
I don't believe I am asking for a 100% answer from the model. And, do not misunderstand, I am not dismissing any argument or technique. However, I am asking for rigorous review of statements and models, which I do not see happening.
For example, I often pick on the astrobiologists' "Drake equation", which is a proposed model for the number of current planets with intelligent life. It suffers from the same problems as the "evolutionary probability" statements, and some models.
You ask - "why don't you come up with something better?". That is what Science and constructive criticism does. I point out some of model deficiencies:
1. We have a sample set of one. We cannot infer generalities from this mathematically (i.e. a priori) - how can we expand our understanding to correct this?
2. Specific conditions, in this place and time, may not be applicable to other conditions - What factors should be applied to the model to correct for this potential difference?
3. Randomness or correlation is incorrectly accounted for in these models - Better understanding of phenomena such as self-organization and emergence would lead to better models.

This message is a reply to:
 Message 3 by Blue Jay, posted 10-05-2008 9:13 AM Blue Jay has replied

Replies to this message:
 Message 9 by Blue Jay, posted 10-05-2008 11:42 AM boysherpa has not replied
 Message 10 by Wounded King, posted 10-05-2008 11:48 AM boysherpa has replied

  
Modulous
Member
Posts: 7801
From: Manchester, UK
Joined: 05-01-2005


Message 8 of 27 (485126)
10-05-2008 11:35 AM
Reply to: Message 6 by boysherpa
10-05-2008 10:47 AM


Re: A good point, modulous
Rather, a closer situation would be to monitor, say, several species' morphological mutation rate in response to specific conditions, and attempting to infer a global "probability" (in time terms as well) that such a "successful" adaptation can occur for a generic species. This will prove difficult, but is what is required for the question at hand.
Such experiments as you describe do occur, and are occurring right now. If for instance, a bacteria that evolves a certain adaptation can be compared with a frozen ancestor to see how often those ancestors subsequently evolve that same adaptation. There comes a point where evolving a certain adaptation becomes almost inevitable.
Given what we know about how the genotype becomes the phenotype, we know that it is essentially impossible to derive any general rule about any specific adaption since what happens in the future evolution is highly contingent on where we start.
However, all evolutionary biologists say is that natural selection is a proven way for complex adaptations to arise (one of the only ways known, in fact). Combine that with the fact of common ancestry, and it would follow that natural selection provides an excellent explanation for how populations can change and how new adaptations can arise.
Showing that an adaptation has occurred reveals nothing about its mathematically probability of occurrence except that it is nonzero
Technically, if we have shown that an adaptation has occurred reveals that its probability of occurance is 1. Evolutionary biology does not rest on being able to calculate the specific probability of certain types of adaptation. Certain adaptations can be calculated, usually in the form of 'given this locus's mutation rate, it would likely take about 25,000 years of change before species A can have adaption B and species B can have adaptation b.'. This is only practical at the gene level - when we start becoming more general things get less precise.
So, 'what is the probability that gene x will duplicate itself and have an insertion mutation (leading to increased muscle mass)?' Might be, at least in principle, something that can be reasonably calculated.
However, it would be very difficult to calculate what is the probability that this lineage, within two generations, will evolve to have greater muscle mass. Maybe for animals we know well (such as cows), a 'good enough' calculation might be worked out - but there are many ways muscle mass could increase, not just genetic ones either. And of course, there are many ways it could decrease. Some genes may change to lead to an increase, while others change to lead to a decrease.
You said in the OP
It would seem then, that we should examine whether any of the probabilistic arguments are even valid at all, mathematically speaking
On the one hand, evolutionary biologists don't make the kinds of probabilistic arguments you refer to. They are simply gathering evidence and trying to explain it as best as they can. From what we have learned so far, it is known that all life is related and natural selection is one explanation.
We also know quite a bit about biochemistry, enough to be confident that there are certain conditions out there which will begin proto-life.
On the other, its detractors often use very specific probabilistic arguments that 'prove' evolution false - despite the fact that the necessary information to make such calculations is non-existent.
The biologist's answer is not a probabilistically based one, and nor is it claimed to be. In its entirety it is a tentative explanation for what facts we have managed to uncover, with full admission that not everything has yet been satisfactorily explained.
The creationist's answer is probabilistically based. It composes of assuming a non-existent world of randomly bumping particles with no forces but an even and constant temperature that is never revealed and concludes that such a world cannot create life through random bumping alone. It is true, but the conclusion given is usually accompanied by a hidden premise that we live in such a world, and thus life in this world could not have a non-theistic origin. So while it is mathematically 'valid', it is logically absurd.

This message is a reply to:
 Message 6 by boysherpa, posted 10-05-2008 10:47 AM boysherpa has replied

Replies to this message:
 Message 14 by boysherpa, posted 10-05-2008 11:42 PM Modulous has not replied

  
Blue Jay
Member (Idle past 2698 days)
Posts: 2843
From: You couldn't pronounce it with your mouthparts
Joined: 02-04-2008


Message 9 of 27 (485127)
10-05-2008 11:42 AM
Reply to: Message 7 by boysherpa
10-05-2008 11:14 AM


Re: Modeling is indeed the key
Hi, Boysherpa.
I think I totally misunderstood the point of your question(s). I read "statistical" where you said "probabilistic." You see, I've recently had several discussions in classes (and one here) about the usefulness of models and statistics, and I think I read that into your post because it's been on my mind.
Sorry.
boysherpa writes:
1. We have a sample set of one. We cannot infer generalities from this mathematically (i.e. a priori) - how can we expand our understanding to correct this?
2. Specific conditions, in this place and time, may not be applicable to other conditions - What factors should be applied to the model to correct for this potential difference?
3. Randomness or correlation is incorrectly accounted for in these models - Better understanding of phenomena such as self-organization and emergence would lead to better models.
Are you still talking about the Drake equation here? Or, is this back to probability in evolutionary models?
At any rate, I think your point #1 is crucial. With either evolution/abiogenesis or the Drake equation, there is only one data point available, so modeling for the larger universe is tricky, but, within our set of data, we can find a lot of underlying patterns.
For example, preferential mating on the part of females has led to all kinds of lekking, sparring and displaying ornaments and behaviors in many different lineages of animals.
That's enough to establish a pattern. And, it might be enough to establish the statistical prevalence of sexual selection in the determination of male phenotypes.
But, again, probabilities are tricky in evolution, because of the myriad possibilities, the inherent difficulty in predicting the potential effects of individual mutations (due to the fledgling nature of genomics and again, to the shear amount of data to be studied), and the apparent case-specificity of the selection pressures. Attempts at estimating mutation rates can be successful and informative, but they can also be variable, so correlation with fossil data is important.

-Bluejay
Darwin loves you.

This message is a reply to:
 Message 7 by boysherpa, posted 10-05-2008 11:14 AM boysherpa has not replied

  
Wounded King
Member
Posts: 4149
From: Cincinnati, Ohio, USA
Joined: 04-09-2003


Message 10 of 27 (485128)
10-05-2008 11:48 AM
Reply to: Message 7 by boysherpa
10-05-2008 11:14 AM


Not equivalent
I am with you on being highly skeptical of most probability arguments in the EvC debate. Having said that I think that the failings in argument 1 and 2 are quite distinct and without more context we can't say whether the 1st argument is actually bade or not. As you formulated it it is incredibly imprecise. I can think of a number of circumstances where it would be a sufficient and credible argument precisely because we have got empirically derived mutational rates to base an estimate off. On the other hand if it was talking abut some highly developed complex trait, like the 2nd argument is, then it would probably be little more than pulling numbers out of a hat.
The second case is considerably worse since not only does it suffer from the pulling numbers out of a hat problem, in terms of determining the probability of a complex trait like the jaw and it associated nervous system structures, but it usually assumes that there is only one possible solution how that trait evolves.
To demonstrate the failing in the first case you really need to contextualise it more.
TTFN,
WK

This message is a reply to:
 Message 7 by boysherpa, posted 10-05-2008 11:14 AM boysherpa has replied

Replies to this message:
 Message 15 by boysherpa, posted 10-05-2008 11:55 PM Wounded King has replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 11 of 27 (485132)
10-05-2008 12:09 PM
Reply to: Message 5 by Agobot
10-05-2008 10:10 AM


Ahhh, Evolution
Well, avoiding the potential spears by claiming evolution is true, I would rather just focus on a specific topic.
Our model should be able to account for both internal and external effects. So, yes, external pressures will have some effects, although I don't know that I would use the term "directed". I have always considered mutations as random. They occur. They may occur more frequently due to an external situation. When an external factor provides a long-term reproductive success filter for a particular mutation-based characteristic, we can say evolution can occur, although it may not. However, neither the environment nor the individual directs this change. Also note that this change may not involve "progress" as we normally consider it.
So, you have brought up some elements of a model!
Probability of a selection factor emerging
Probability of mutation occurring
Probability of stable outcome

This message is a reply to:
 Message 5 by Agobot, posted 10-05-2008 10:10 AM Agobot has replied

Replies to this message:
 Message 12 by Agobot, posted 10-05-2008 12:20 PM boysherpa has replied

  
Agobot
Member (Idle past 5530 days)
Posts: 786
Joined: 12-16-2007


Message 12 of 27 (485133)
10-05-2008 12:20 PM
Reply to: Message 11 by boysherpa
10-05-2008 12:09 PM


Re: Ahhh, Evolution
boysherpa writes:
Well, avoiding the potential spears by claiming evolution is true, I would rather just focus on a specific topic.
Well, there is compelling evidence that evolution is in fact true. A creator doesn't necessarily have to invalidate evolution, unless you believe in the holy books' description of the creator and that the earth is 6000 years old, man did not descend fom homo-habilis, etc..
PS. Piece of friendly advice, i see you are new here - don't question the existence of Evolution on this forum, you'll get stomped.
Edited by Agobot, : No reason given.
Edited by Agobot, : No reason given.

This message is a reply to:
 Message 11 by boysherpa, posted 10-05-2008 12:09 PM boysherpa has replied

Replies to this message:
 Message 13 by boysherpa, posted 10-05-2008 11:14 PM Agobot has not replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 13 of 27 (485168)
10-05-2008 11:14 PM
Reply to: Message 12 by Agobot
10-05-2008 12:20 PM


Re: Ahhh, Evolution
Thanks for the friendly advice. I seem to appear to be anti-evolution. What is the word - how droll!
Funny, I am not interested in the least in that debate. Anyone who wants to debate evolution vs creation is in it for neither science nor faith reasons - its about control. A scientist does not attempt to prove truth. Anyone wishing to stomp - have at it, its childish, and you lose scientific respect at an exponential rate. We should, however, hypothesize, test, revise, and move forward.
If we are to truly be scientific, then we must accept all challenges and questions with an open mind and patience. If all we have is name calling, then we are lost.

This message is a reply to:
 Message 12 by Agobot, posted 10-05-2008 12:20 PM Agobot has not replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 14 of 27 (485170)
10-05-2008 11:42 PM
Reply to: Message 8 by Modulous
10-05-2008 11:35 AM


more model details
Modulous, you have elucidated more good details in your replies. Thanks!
Think with me (I am just exploring here):
However, all evolutionary biologists say is that natural selection is a proven way for complex adaptations to arise (one of the only ways known, in fact).
Could display behaviors be separable from other natural selection mechanisms in that is not necessarily due to a factor outside of the species itself? This is simply an attempt to identify the forms of any potential models.
Certain adaptations can be calculated, usually in the form of 'given this locus's mutation rate, it would likely take about 25,000 years of change before species A can have adaption B and species B can have adaptation b.'. This is only practical at the gene level - when we start becoming more general things get less precise.
Excellent - now we can look at a modeling exercise. If a mutation rate is measured locally, and assumed constant (unclear), then we can use this as an independent, separable probability term in the model. However, if it is correlated to another variable, our model is a bit trickier. For example, if environmental radiation is the chief source of mutation, and a burst of radiation modifies the rates as well as exerting other environmental pressures such as a food source deprivation, the relationships may be difficult to ferret out.
I appreciate what you explain about the difficulty of modeling evolutionary processes. I think you raise a good point about trying to keep things simple in the modeling arena.
P.S.
Technically, if we have shown that an adaptation has occurred reveals that its probability of occurance is 1.
I don't believe you meant to say this. If this were true, the fact that there was a lottery win this weekend means there will be a lottery win next weekend, in fact, it means every drawing must result in a winner, simply because there was once a winner.

This message is a reply to:
 Message 8 by Modulous, posted 10-05-2008 11:35 AM Modulous has not replied

  
boysherpa
Junior Member (Idle past 5372 days)
Posts: 19
From: Lomita, CA
Joined: 10-04-2008


Message 15 of 27 (485174)
10-05-2008 11:55 PM
Reply to: Message 10 by Wounded King
10-05-2008 11:48 AM


Re: Not equivalent
Thanks for pointing out my weak posting.
First, case 2 is the hot air balloon which got me on this soap box. So, I am glad to hear that someone else agrees.
Case 1 does need some definition. I think when someone does ask a question like "how did a jawless fish evolve into a jawed fish", the scientist owes a good answer, not just name-calling and deep-diving into Latin ponds. It is not enough to claim that this happened over "hundreds of millions of years" (in many cases, it doesn't seem to have). I give credit to Behe's book "Darwin's Black Box" for asking good questions, although I am not sure his analyses was thorough or that he conferred before release. I would have to give "the scientific community" (TSC) a solid C for its response to the book. Not that they don't know their stuff, but they tried to make him a crackpot. He asked reasonable questions. TSC did not give reasonable responses. They attacked him. Bad form, for scientists, but not unusual.
Creationists, on the other hand, don't really know what Darwin's ideas were, and how it pained him to publish them. Darwin was truly one of the few great minds of the human race.
P.S.
Some of my best ancestors were from Scotland! (Ferguson)

This message is a reply to:
 Message 10 by Wounded King, posted 10-05-2008 11:48 AM Wounded King has replied

Replies to this message:
 Message 17 by Wounded King, posted 10-06-2008 11:26 AM boysherpa has replied

  
Newer Topic | Older Topic
Jump to:


Copyright 2001-2023 by EvC Forum, All Rights Reserved

™ Version 4.2
Innovative software from Qwixotic © 2024