Phizzy Said this......And I am afraid I disagree (page 9)

cofty

That's ok.

There are thousands of other things I am certain of if you want to play some more.

Oubliette

No thanks. I'm not interested in going off on absurd tangents.

cofty

Neither am I.

I am simply pointing out that complete uncertainty is not a virtue.

We know lots of stuff for certain.

Earnest

cofty : A computer programme was written that simulates natural selection and it created text from Shakespeare in a very few generations.

Of course the computer programme had some intelligence behind it and I would be interested to know how accurately it simulated natural selection. Do you have any references with which I could verify this please.

cofty

Earnest - It was described by Richard Dawkins in "The Blind Watchmaker".

Take the line from Hamlet, "Methinks it is like a weasel".

The chances of monkeys with typewriters producing this phrase exactly is 1 in 10,000 million million million million million million.

This is what we might call single-step selection

However if we apply a cumulative-selection process it becomes very easy to produce this phrase.

First the computer produces a random line of 28 characters.

Next it "breeds" from this first generation by producing multiple copies of it but with a certain amount of random error or mutation built in.

Now the computer selects the second generation that is closest to target phrase.

and so on...

The programme wasn't trying to create the target phrase it was simply producing random mutations and then selecting the one that looked the most promising.

It turned out the phrase "Methinks it is like a weasel" in just 48 generations.

It illustrates quite well how evolution by natural selection works.

Genes suffer mutations which cause unpredictable changes in the bodies they build. If the change is even very very slightly beneficial that body has a better chance of passing on that gene to the next generation.

When people express incredulity about natural processes producing complexity it is usually because they are thinking in terms of single-step selection.

Oubliette

Cofty: I am simply pointing out that complete uncertainty is not a virtue.

I didn't suggest it was.

Cofty: We know lots of stuff for certain.

Of course. But being "certain" about something does not necessarily make it so. I know from reading other of your posts that there are things which you once believed that you no longer believe.

I suspect you were "certain" about those beliefs when you held them to be true.

Even well-established scientific facts are subject to revision when new, compelling evidence becomes known.

cofty

I suspect you were "certain" about those beliefs when you held them to be true

Yes they were faith-based positions. They amounted to wishful thinking.

Evidence-based conclusions about the world are a different thing. Our certainty should be commensurate with the evidence.

Oubliette

Cofty: Our certainty should be commensurate with the evidence.

Agreed.

Nevertheless, being rational requires sometimes revising our beliefs when the evidence suggests it the prudent, logical thing to do, no matter how certain we were previously.

cofty

Of course, but to say.. "we can never really be certain of anything. I'm very sure of this!" is to seriously overstate the case.

There are thousands of things we could state right now with certainty.

Oubliette

I would have thought that you would have understood I was being somewhat facetious by ending my statement with the phrase, "I'm very sure of this!"

Phizzy Said this......And I am afraid I disagree

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