Chance

[Barry Desborough]

This comes out of an exchange with JM in this_thread

Post# 110
Whats to learn about evolution anyway. Let me in on the jig.

OK JM, let's start with one basic notion that comes into many sciences and many aspects of ordinary life, namely chance or randomness.

A theist may believe that there is no such thing as true randomness in this universe. Every event is just as it is because it is His will and He can see to it that everything happens just as it should according to His plan. I don't want to argue with this, so I'll take the position here that this is so.

There are several instances of casting lots in the Bible, so I can also take the position that the casting of lots, which to us mortals is the generation of seemingly random events, is an instrument of His will.

Let's think about why, nevertheless, we still see certain events as being random. We cannot predict them. Firstly, we cannot second-guess the actions of God. Secondly, even if it were possible in principle to predict, say, the roll of a die, the model we would use to generate such a prediction would be as complex as the natural experiment itself. It would yield no more information than if we hadn't bothered to create the model, other than confirming that the model works.

So, for the purposes of this discussion, I'll define a random event as an event that we cannot discern the cause of, except by an appeal to God. We can, however, recognise random events. There is a lot of sophisticated mathematics on this subject, but we don't need to go into it here. We all intuitively recognise chance. In its simplest manifestations, like rolling a die or flipping a coin, all events from our point of view are equally likely to occur and there is no discernible pattern to the results.

Let me pause here to give you the opportunity to come back with questions or points, but please keep your response directly relevant to this post.

P.S. Sorry about the font mix-up. All looks normal in the edit box, but it won't come out right.

[johnmartin]

[font=Arial]

This comes out of an exchange with JM in

this_thread

OK JM, let's start with one basic notion that comes into many sciences and many aspects of ordinary life, namely chance or randomness.

A theist may believe that there is no such thing as true randomness in this universe. Every event is just as it is because it is His will and He can see to it that everything happens just as it should according to His plan. I don't want to argue with this, so I'll take the position here that this is so.

There are several instances of casting lots in the Bible, so I can also take the position that the casting of lots, which to us mortals is the generation of seemingly random events, is an instrument of His will.

Let's think about why, nevertheless, we still see certain events as being random. We cannot predict them. Firstly, we cannot second-guess the actions of God. Secondly, even if it were possible in principle to predict, say, the roll of a die, the model we would use to generate such a prediction would be as complex as the natural experiment itself. It would yield no more information than if we hadn't bothered to create the model, other than confirming that the model works.

So, for the purposes of this discussion, I'll define a random event as an event that we cannot discern the cause of, except by an appeal to God. We can, however, recognise random events. There is a lot of sophisticated mathematics on this subject, but we don't need to go into it here. We all intuitively recognise chance. In its simplest manifestations, like rolling a die or flipping a coin, all events from our point of view are equally likely to occur and there is no discernible pattern to the results.

Let me pause here to give you the opportunity to come back with questions or points, but please keep your response directly relevant to this post.

P.S. Sorry about the font mix-up. All looks normal in the edit box, but it won't come out right.

Tell me why you defined a random event as an event that we cannot discern the cause of, except by an appeal to God. Here are some examples of random events in which we know many causes

1. The lotto results have a series of balls giving a series of numbers caused by the machine.
2. Man finds treasure when digging a hole to plant a tree
3. A man finds a coin on the pavement by accident.
4. Car accidents.
5. Tossing a coin.

In the examples above we have known causes and known natures. Your definition needs to be revised. You should do this by firstly discussing what an act is, also and event and include the notions of nature and end. I think you will find they are all related to the notion of chance. You can adopt the notion of chance as -

Chance or luck is nothing else than a very rare occasion, or IOW, "when the accident has a connection with the effect, yet not a necessary connection, nor in most cases, but seldom, as the finding of a treasure is connected with digging of the soil".

(Aristotle - In V Metaphysics.).

What happens by chance is an effect which is not explainable from a determinate cause, because such a cause is not ‘per se or of itself’ ordered to it. But rather, this effect is produced ‘per accidens or of other’, that is, owing to the concurrence of some other cause or causes which are not taken into an account; or in other words, owing to a criss-cross of causes which is not considered.

Therefore the finding of the treasure (2 above) arises from the concurrence of two causalities, which are the action of digging and also the action of the man who hid the treasure. Accordingly chance truly exists both in reality, but only through relation to a particular cause, and in the mind of one who takes account only of a particular cause, but on the other hand, absolutely chance does not exist. Because with respect to the universal cause (God) upon which every particular cause depends, also the effects arising from the concurrence of particular causes with each other are foreseen.

Therefore from the notion of chance no conclusion can be drawn against finality in things (and final causation that supposes intellect). As every particular cause intends its own particular effect and the universal cause intends its own particular effect. The universal cause intends not only such particular effects, but also effects derived from the mixing of particular causes, - even though these latter effects considered through reference to some are particular cause alone are known as fortuitous.

Therefore any attempt to explain everything through chance, is absurd in itself, and is not an explanation at all.

JM

[Barry Desborough]

Tell me why you defined a random event as an event that we cannot discern the cause of, except by an appeal to God. Here are some examples of random events in which we know many causes

1. The lotto results have a series of balls giving a series of numbers caused by the machine.
2. Man finds treasure when digging a hole to plant a tree
3. A man finds a coin on the pavement by accident.
4. Car accidents.
5. Tossing a coin.

I'll just take 1) and 5) for now.

1) The proximate cause of of the lotto results is the action of the machine. The cause of the machine operating is someone switching it on. The cause of someone switching it on is....

5) The cause of the result of a coin-toss is someone flipping it. The cause of someone flipping... and so on.

In the examples above we have known causes and known natures. Your definition needs to be revised. You should do this by firstly discussing what an act is, also and event and include the notions of nature and end. I think you will find they are all related to the notion of chance. You can adopt the notion of chance as -

Chance or luck is nothing else than a very rare occasion, or IOW, "when the accident has a connection with the effect, yet not a necessary connection, nor in most cases, but seldom, as the finding of a treasure is connected with digging of the soil".

(Aristotle - In V Metaphysics.).

Chance and luck are closely related, but by the word 'chance', I mean more the lack of a necessary connection rather than rarity. Rarity is not a necessary aspect of chance as I mean it. Lack of a necessary connection is good.

What happens by chance is an effect which is not explainable from a determinate cause, because such a cause is not ‘per se or of itself’ ordered to it. But rather, this effect is produced ‘per accidens or of other’, that is, owing to the concurrence of some other cause or causes which are not taken into an account; or in other words, owing to a criss-cross of causes which is not considered.

And which we may not even be capable of considering (see my OP).

Therefore the finding of the treasure (2 above) arises from the concurrence of two causalities, which are the action of digging and also the action of the man who hid the treasure. Accordingly chance truly exists both in reality, but only through relation to a particular cause, and in the mind of one who takes account only of a particular cause, but on the other hand, absolutely chance does not exist. Because with respect to the universal cause (God) upon which every particular cause depends, also the effects arising from the concurrence of particular causes with each other are foreseen.

Therefore from the notion of chance no conclusion can be drawn against finality in things (and final causation that supposes intellect). As every particular cause intends its own particular effect and the universal cause intends its own particular effect. The universal cause intends not only such particular effects, but also effects derived from the mixing of particular causes, - even though these latter effects considered through reference to some are particular cause alone are known as fortuitous.

OK.

Therefore any attempt to explain everything through chance, is absurd in itself, and is not an explanation at all.

JM

I touched on the universal cause in my OP. The overall, ultimate cause of the action is not of interest at the moment (we may come back to it).

Nowhere have I attempted to explain everything through chance, John. I merely wanted to make sure we could both use the words 'chance' and randomness' in the same sense as one another.

OK. I think we have an agreed notion of chance where there is a lack of a necessary connection between the proximate cause (the imediate action) and the effect (the outcome).

~~~~~~~~~~~~~~~~~~~~~~~~~~

In a die throw, for example, we don't need to know why someone is throwing a die in order to know that the numbers 1 through 6 will come up with equal probability. We can work this out from logic, or we can check it out ourselves with our own dice. OK?

Now, I expect you know where this is leading.

We don't need to know an ultimate cause of genetic mutations occurring to know that there is a lack of a necessary connection between the proximate cause (radiation, chemical interactions etc.) and the result. We see it happen, and we can see that the results happen by chance. We call it random mutation. Is this OK too?

[johnmartin]

I'll just take 1) and 5) for now.

1) The proximate cause of of the lotto results is the action of the machine. The cause of the machine operating is someone switching it on. The cause of someone switching it on is....

5) The cause of the result of a coin-toss is someone flipping it. The cause of someone flipping... and so on.


Chance and luck are closely related, but by the word 'chance', I mean more the lack of a necessary connection rather than rarity. Rarity is not a necessary aspect of chance as I mean it. Lack of a necessary connection is good.

And which we may not even be capable of considering (see my OP).

OK.


I touched on the universal cause in my OP. The overall, ultimate cause of the action is not of interest at the moment (we may come back to it).

Nowhere have I attempted to explain everything through chance, John. I merely wanted to make sure we could both use the words 'chance' and randomness' in the same sense as one another.

OK. I think we have an agreed notion of chance where there is a lack of a necessary connection between the proximate cause (the imediate action) and the effect (the outcome).

~~~~~~~~~~~~~~~~~~~~~~~~~~

In a die throw, for example, we don't need to know why someone is throwing a die in order to know that the numbers 1 through 6 will come up with equal probability. We can work this out from logic, or we can check it out ourselves with our own dice. OK?

Now, I expect you know where this is leading.

We don't need to know an ultimate cause of genetic mutations occurring to know that there is a lack of a necessary connection between the proximate cause (radiation, chemical interactions etc.) and the result. We see it happen, and we can see that the results happen by chance. We call it random mutation. Is this OK too?

The ultimate cause of any secondary cause is God. The empirical sciences do not invoke the ultimate cause as it does not come directly under its ambit.

"there is a lack of a necessary connection between the proximate cause (radiation, chemical interactions etc.) and the result" means you dont know the connection or cause producing the result. This then is not to be included in a theory as a theory moves beyond conjecture to using scientific facts within a model. Accordingly I cannot accept your statement as it relates to the theory of evolution as you currently state it.

Instead of dancing around the points lets see you make a big post that reveals all and then we can dialogue about any small points in your post in depth. These slowly slowly posts dont go anywhere. Chance has been defined and thats it so far. You started this thread to let me in on the big jig of evolution. I'd like you to do that within the next one or two posts, otherwise I will leave. I'm not into playing games on a subject I consider to be a playground of unbelief.
JM

[Barry Desborough]

The ultimate cause of any secondary cause is God. The empirical sciences do not invoke the ultimate cause as it does not come directly under its ambit.

"there is a lack of a necessary connection between the proximate cause (radiation, chemical interactions etc.) and the result" means you dont know the connection or cause producing the result. This then is not to be included in a theory as a theory moves beyond conjecture to using scientific facts within a model. Accordingly I cannot accept your statement as it relates to the theory of evolution as you currently state it.

Instead of dancing around the points lets see you make a big post that reveals all and then we can dialogue about any small points in your post in depth. These slowly slowly posts dont go anywhere. Chance has been defined and thats it so far. You started this thread to let me in on the big jig of evolution. I'd like you to do that within the next one or two posts, otherwise I will leave. I'm not into playing games on a subject I consider to be a playground of unbelief.
JM

I'm not dancing around, JM. I'm proceeding in little steps. I assure you that I'm not playing a game. It is because the purpose is to 'let you in on the big jig', and because discussions with you tend to go down wormholes into strange dimensions that I am doing it this way. A reminder, I am not even attempting to persuade you of the theory, merely check over with you what it says. So let's continue.

~~~~~~~~~~~~~~~~~~

The empirical sciences do not invoke the ultimate cause

Good. Agreed.

you dont know the connection or cause producing the result. This then is not to be included in a theory as a theory moves beyond conjecture to using scientific facts within a model. Accordingly I cannot accept your statement as it relates to the theory of evolution as you currently state it

I'm only talking about the lack of a necessary connection John. A lack of a necessary connection between a cause and a finite range of effects. Think of basic probability. We don't know why on one particular instance a die comes up 3 and on another, it comes up 5. We do know the results will range between 1 and 6 without any necessary connection between any particular throw and the result. We have a theory of simple probability with which we can model the behaviour of a die. We can't use the model to predict the precise sequence of die-rolls, but we can predict the statistics of the overall results of a number of rolls.

This shows you why I'm proceeding slowly, step by step. A die can come up anywhere between 1 and 6. A mutation can occur anywhere in a stretch of DNA. OK?

I'm going to assume you follow that last paragraph and I'll continue with another little step.

A mutation will change a piece of DNA. That's a tautology. The change may affect what the DNA does, or it may not have any discenible effect at all.

All OK so far, John?

[johnmartin]

B- I'm only talking about the lack of a necessary connection John. A lack of a necessary connection between a cause and a finite range of effects. Think of basic probability. We don't know why on one particular instance a die comes up 3 and on another, it comes up 5. We do know the results will range between 1 and 6 without any necessary connection between any particular throw and the result. We have a theory of simple probability with which we can model the behaviour of a die. We can't use the model to predict the precise sequence of die-rolls, but we can predict the statistics of the overall results of a number of rolls.

This shows you why I'm proceeding slowly, step by step. A die can come up anywhere between 1 and 6. A mutation can occur anywhere in a stretch of DNA. OK?

I agree with the dice example but you need to demonstrate the DNA example.

JM- I'm going to assume you follow that last paragraph and I'll continue with another little step.

A mutation will change a piece of DNA. That's a tautology. The change may affect what the DNA does, or it may not have any discenible effect at all.

All OK so far, John?

Its only ok in so far as what you have said is partially true, however it ignores any discussion on causation. You can posit what you say above, but the reality is more complex than this and involves notions that only a philosopher can properly enunciate. I will highlight some problems as we go along.

Regarding chance, the following is to be noted.

1. Chance requires causation to occur.
2. Chance requires an end be obtained that was not intended by an act essentially ordered towards another end.
3. Chance will never be absolutely random as it will always occur within laws of nature
4. Chance ends obtained in any particular act cannot be predicted absolutely but may be approximated according to probability. The chance of any particular act is then only relative chance.
5. Chance requires the action of the four causes to occur.
6. Chance pre-requires the existence of natures and intellect. The intellect may be in the agent acting as when a man acts with intellect to toss a coin. Or it may infer an intellect outside the agent acting and then in another agent, such as the random action of wind infers the divine intellect through the notion of teleology.
7. Chance does not contradict any principle of reason.

If you agree with all the above then proceed, otherwise you can critique any of the above points.

JM

[Roy]

Chance pre-requires the existence of natures and intellect.

Right... so presumably a roughly cubic crystal which is ejected during a volcanic eruption on Io must hover above the surface since it cannot land by chance on any of its 6 sides due to no intellect being involved.

But I see you've added the idea of divine intellect, which would presumably apply in the above case, thus resolving the problem.

So what you actually mean is not that chance requires intellect, but that movement requires a god.

Chance does not pre-require intellect. It may pre-require movement, but then if movement can occur without intellect - which is the case in philosophies other than yours - so can chance.

Roy

[johnmartin]

Right... so presumably a roughly cubic crystal which is ejected during a volcanic eruption on Io must hover above the surface since it cannot land by chance on any of its 6 sides due to no intellect being involved.

But I see you've added the idea of divine intellect, which would presumably apply in the above case, thus resolving the problem.

So what you actually mean is not that chance requires intellect, but that movement requires a god.

Chance does not pre-require intellect. It may pre-require movement, but then if movement can occur without intellect - which is the case in philosophies other than yours - so can chance.

Roy

Yeh right . . .check that principle of teleological ordering that demonstrates an intellect must exist whenever there is something that is limited in any manner whatsoever. I've posted it on two or three threads. I'm 99% sure you've seen it. It was on the Just How Do . . .thread.
JM

[Barry Desborough]

Right... so presumably a roughly cubic crystal which is ejected during a volcanic eruption on Io must hover above the surface since it cannot land by chance on any of its 6 sides due to no intellect being involved.

But I see you've added the idea of divine intellect, which would presumably apply in the above case, thus resolving the problem.

So what you actually mean is not that chance requires intellect, but that movement requires a god.

Chance does not pre-require intellect. It may pre-require movement, but then if movement can occur without intellect - which is the case in philosophies other than yours - so can chance.

Roy

I shoulda put this thread in the Basketball Court. I welcome any comments, but as John and I have a nice little chat going here, I've created an alternative thread for comments. 'Comments: Chance'.

[Barry Desborough]

I agree with the dice example but you need to demonstrate the DNA example.

Its only ok in so far as what you have said is partially true, however it ignores any discussion on causation. You can posit what you say above, but the reality is more complex than this and involves notions that only a philosopher can properly enunciate. I will highlight some problems as we go along.

Regarding chance, the following is to be noted.

1. Chance requires causation to occur.
2. Chance requires an end be obtained that was not intended by an act essentially ordered towards another end.
3. Chance will never be absolutely random as it will always occur within laws of nature
4. Chance ends obtained in any particular act cannot be predicted absolutely but may be approximated according to probability. The chance of any particular act is then only relative chance.
5. Chance requires the action of the four causes to occur.
6. Chance pre-requires the existence of natures and intellect. The intellect may be in the agent acting as when a man acts with intellect to toss a coin. Or it may infer an intellect outside the agent acting and then in another agent, such as the random action of wind infers the divine intellect through the notion of teleology.
7. Chance does not contradict any principle of reason.

If you agree with all the above then proceed, otherwise you can critique any of the above points.

JM



[/size]

John, I probably won't be able to post for a few hours, but I don't think we have any stumbling-blocks here. I'll get back on all these points and continue as soon as I am free to do so.

[johnmartin]

John, I probably won't be able to post for a few hours, but I don't think we have any stumbling-blocks here. I'll get back on all these points and continue as soon as I am free to do so.

Chance your arm when your ready.
JM

[Barry Desborough]

Right. Time to chance my arm (or at least my brain and my fingers on the keyboard).

I agree with the dice example but you need to demonstrate the DNA example.

This Wikipedia entry is a good place to find all the processes and the jargon involved in how DNA gets changed. There are many different processes by which it happens. If you want to get into more detail and look at the mechanics, try googling for mutational mechanisms.

The main points to note are that 1) mutations occur by known physical processes, and 2) there is no evidence that any given instance of a mutation occurs in any way that is directed to a specific result* (more on this below). By 'directed to a specific result', I merely mean that we don't see anything 'fishy' going on like, by analogy with dice, a fair die that only ever comes up with even numbers.

Note also that none of this knowledge about genetics and mutations strictly requires us to assume the theory of evolution!

Its only ok in so far as what you have said is partially true, however it ignores any discussion on causation. You can posit what you say above, but the reality is more complex than this and involves notions that only a philosopher can properly enunciate. I will highlight some problems as we go along.

Regarding chance, the following is to be noted.

1. Chance requires causation to occur.
2. Chance requires an end be obtained that was not intended by an act essentially ordered towards another end.
3. Chance will never be absolutely random as it will always occur within laws of nature
4. Chance ends obtained in any particular act cannot be predicted absolutely but may be approximated according to probability. The chance of any particular act is then only relative chance.
5. Chance requires the action of the four causes to occur.
6. Chance pre-requires the existence of natures and intellect. The intellect may be in the agent acting as when a man acts with intellect to toss a coin. Or it may infer an intellect outside the agent acting and then in another agent, such as the random action of wind infers the divine intellect through the notion of teleology.
7. Chance does not contradict any principle of reason.

If you agree with all the above then proceed, otherwise you can critique any of the above points.

JM

1. Chance requires causation to occur. Yes. To get a score on a die, you've got to roll it. To get a mutation, you need radiation, a mutagenic chemical or any other of the causes mentioned in the Wikipedia article.
2. Chance requires an end be obtained that was not intended by an act essentially ordered towards another end. Whether the act was intended towards another end or not, you can look at a mutation as being towards an end that was not intended, or you can even look at it, if you want, as an act towards an end, but employing randomness.*
3. Chance will never be absolutely random as it will always occur within laws of nature. Yes. There is a good reason you don't get a 7 on a normal die. There are good reasons why mutations only produce different sequences of base pairs. Any other changes are outright damage, analagous to smashing the die.
4. Chance ends obtained in any particular act cannot be predicted absolutely but may be approximated according to probability. The chance of any particular act is then only relative chance. OK. This is similar to 3) I think. We don't say that chance means absolutely anything can happen, and we recognise that it is constrained by the laws of probability.
5. Chance requires the action of the four causes to occur. See *.
6. Chance pre-requires the existence of natures and intellect. The intellect may be in the agent acting as when a man acts with intellect to toss a coin. Or it may infer an intellect outside the agent acting and then in another agent, such as the random action of wind infers the divine intellect through the notion of teleology. See *.
7. Chance does not contradict any principle of reason. I don't plan to propose anything that contradicts the principle of reason.

* Re. notions of proximate causes, ultimate causes and acts towards an end:-

For the purposes of this thread, I've taken the position of a theistic evolutionist. This position assumes that everything that happens in this universe happens towards an end, and that the chain of causation stretches all the way from the unmoved mover to the tiniest crevices of sub-atomic processes. This position is different to that of an ID advocate. The TE sees evolution as being the method by which God's plan unfolds. Either chance events are just part of that method, actually random, or each individual event has a specific purpose, even if we call it chance because we cannot understand it on its own. The ID advoate, at least the ones who propose 'directed evolution', look for evidence of things which cannot have happened by chance. They look for skewed results in the dice-rolls, as it were, contrary to nature, unless one adds in an extra factor.

Now the main point I would want to stress to you about mutations is that, regardless of questions about causality, what we are really interested in here at the moment are it's efects. We are looking 'down' the causal chain. Looking in this direction, the TE and the non-theistic evolutionist see the same things, the effects of DNA getting changed. Like a student of auto-mechanics wanting to understand how a car works, he is not immediately interested in the macro-economics of the auto industry. He wants to look under the hood of this Chevvy.

However, I'm a bit tired and hungry right now. Hopefully the mods will indulge me and allow me to continue this a bit later.

[Barry Desborough]

... Hopefully the mods will indulge me and allow me to continue this a bit later.

So far, we have mutations - changes in the DNA due to proximate physical causes which appear to act at random.

Let's leave mutation aside for the moment and talk about variation, independently of the subject of mutation.

All species show variation. By species, I mean a group of organisms that can interbreed and produce fertile offsping. I know that restricts it to sexually reproducing species - I choose them because they illustrate a number of things more clearly. Variation is undeniable. Unless you have identical twins/triplets etc., every member of a given species is different. If we look down at the level of their DNA, we find differences there. We know that many of the differences between individuals are due to these differences in their DNA.

Different individuals have lives that run different courses. Some are slow and tend to be easy prey for predators. Some are fast, or smart, and tend to live longer. Some are co-operative, and reap the benefits of a social life. Some are uncooperative, get shunned, and don't do very well. And so on, through a whole range of qualities that can influence the course of an individual's life.

The next step on our walk is to recognise that differences in DNA affect these life courses, particularly that they affect the number of offsping individuals are likely to contribute to following generations.

~~~~~~~~~~~~~~~~~~~~

John, if you want me to continue without picking up on anything, please just post an 'OK', but don't do it just to let me lay it all out then hit me with a bag of bricks at the end. I have many necessary and worthwhile things I could be doing. Thankyou.

[johnmartin]

B- * Re. notions of proximate causes, ultimate causes and acts towards an end:-

For the purposes of this thread, I've taken the position of a theistic evolutionist. This position assumes that everything that happens in this universe happens towards an end, and that the chain of causation stretches all the way from the unmoved mover to the tiniest crevices of sub-atomic processes. This position is different to that of an ID advocate. The TE sees evolution as being the method by which God's plan unfolds. Either chance events are just part of that method, actually random, or each individual event has a specific purpose, even if we call it chance because we cannot understand it on its own. The ID advoate, at least the ones who propose 'directed evolution', look for evidence of things which cannot have happened by chance. They look for skewed results in the dice-rolls, as it were, contrary to nature, unless one adds in an extra factor.

When I say the four causes I mean the formal, material, efficient and final causes. When I say acts for an end, every act must do this to comply with the principles of identity, sufficient reason and finality.

Are you a theist? If so its good to know.

B- Now the main point I would want to stress to you about mutations is that, regardless of questions about causality, what we are really interested in here at the moment are it's effects. We are looking 'down' the causal chain. Looking in this direction, the TE and the non-theistic evolutionist see the same things, the effects of DNA getting changed. Like a student of auto-mechanics wanting to understand how a car works, he is not immediately interested in the macro-economics of the auto industry. He wants to look under the hood of this Chevvy.

However, I'm a bit tired and hungry right now. Hopefully the mods will indulge me and allow me to continue this a bit later.

So far, we have mutations - changes in the DNA due to proximate physical causes which appear to act at random.

But do they appear to act randomly or do they really act randomly and if so what are the restrictions on this random behaviour? If there are no restrictions then we should see giant changes from one generation to the next. As we don't see this, then there must be restrictions. The limits then need to be determined and then shown to be compatible with any theory invoked.

B- Let's leave mutation aside for the moment and talk about variation, independently of the subject of mutation.

All species show variation. By species, I mean a group of organisms that can interbreed and produce fertile offsping. I know that restricts it to sexually reproducing species - I choose them because they illustrate a number of things more clearly. Variation is undeniable. Unless you have identical twins/triplets etc., every member of a given species is different. If we look down at the level of their DNA, we find differences there. We know that many of the differences between individuals are due to these differences in their DNA.

Different individuals have lives that run different courses. Some are slow and tend to be easy prey for predators. Some are fast, or smart, and tend to live longer. Some are co-operative, and reap the benefits of a social life. Some are uncooperative, get shunned, and don't do very well. And so on, through a whole range of qualities that can influence the course of an individual's life.

The next step on our walk is to recognise that differences in DNA affect these life courses, particularly that they affect the number of offsping individuals are likely to contribute to following generations.

~~~~~~~~~~~~~~~~~~~~

John, if you want me to continue without picking up on anything, please just post an 'OK', but don't do it just to let me lay it all out then hit me with a bag of bricks at the end. I have many necessary and worthwhile things I could be doing. Thankyou.

The above few paragraphs are broad statements that are substantially true. Nevertheless I can see some problems around the corner. Continue.

JM

[Barry Desborough]

Are you a theist? If so its good to know.

I don't advertise my 'position' because

• I don't apply any of the choices to myself.
• I prefer people to read and consider what I write without viewing it through coloured spectacles.
• I don't think in terms of God as most people seem to mean the word.
• My position is not something that words are very good at communicating.

Do I think there is a point to existence? Yes, but I think it's up to us to work it out. Sorry, but that's the best I can do in answer to your question. I hope you appreciate that it is an aside. As I said, I'm adopting a theistic evolutionist stance in this thread. Theism/atheism is not in itself relevant to evolution. Only certain forms of theism are incompatible with it.

But do they [mutations] appear to act randomly or do they really act randomly and if so what are the restrictions on this random behaviour? If there are no restrictions then we should see giant changes from one generation to the next. As we don't see this, then there must be restrictions. The limits then need to be determined and then shown to be compatible with any theory invoked.~

For the purposes of the theory, it doesn't matter if mutations appear random or actually are random. We are only looking at the effects, which are identical.

It is an essential part of the theory that we do not see giant changes from one generation to the next. The reason is a simple application of probability. Small changes are statistically much more likely than gross ones, and this is indeed what we see. Quantifying this is extremely complicated, but bear in mind, our intuitions about probability are not very reliable when we look at large numbers - when we envisage large populations over large numbers of generations.

If needs be, we can go back over this question when I integrate mutation with the other basic ideas of the theory.

The above few paragraphs [on differential reproduction being influenced by genetics] are broad statements that are substantially true. Nevertheless I can see some problems around the corner. Continue.

JM

Thanks. I see likely problems coming too, but I'll be interested to know when and why they might appear. Do remember though, my posts are for elucidation rather then persuasion. If at some point you find yourself rejecting a step, but you still want me to continue because at least it helps you understand better exactly what it is that you are rejecting, let me know. I'll still be prepared to carry on.

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So, to recap, we have individuals of a sexually reproducing species varying in the number of offsping they leave in subsequent generations. This leads nicely into the technical meaning(s) of biological fitness.

Recall that individual members of a species have differences in their DNA. However, much of their DNA will be the same. The major functional part of DNA is sectioned into genes, which usually code for proteins. The differences between individuals are the results of only certain genes being different between them, while the rest of their genomes remain the same.

Here's an outline of the idea. Each column represents the genome of a different individual. They are different because each one has a different version of 'gene 2'. (Different versions of a given gene are called alleles.)

GENE 1 ------- GENE 1
GENE 2a ------ GENE 2b
GENE 3 ------- GENE 3
GENE 4 ------- GENE 4
......... ------- ..........

If we look at how often we find a certain allele for gene 2 in a population, say gene 2a, then test again in the next generation, we can see if it has increased or decreased. If it has increased, we say it has a high fitness value. If it has decreased, it has a low fitness value. That, very basically, is all there is to the idea of biological fitness - quantifying the value of the attributes contributing to an allele's frequency of appearance in subsequent generations. It doesn't apply to species. Strictly speaking, it doesn't even apply to individual organisms, though we tend to say that a highly fit individual is one that posesses high fitness alleles.

A more detailed discussion of fitness can be found in this Wikipedia article. It has good links to related ideas and the jargon involved.

(Pausing again to check with you, John.)