Confidence in evolutionary science

So why am I so confident?

Converging linesI am not going to go into all the pieces of evidence, in all their glorious detail here. Some examples might follow. If I ask someone for directions and he points northwest. I don't follow his directions and later I ask someone for directions to the same place and she points northeast. I might infer, assuming honesty, that the location of my destination is somewhere near where lines extending from the fingers of the two pointers cross. That is to say, the lines converge upon a single location. If I wander aimlessly around and continue to ask people, and whenever they point I draw another line on a map I should expect to find that the lines all cross at a particular point. If I have wandered in something of a circle around my destination, I should have quite a pretty pattern of lines all converging on one spot on my map (excuse the crudeness of the diagram): We can, in this case, be fairly confident that we know where X happens to be (I choose X because it is visually representative of converging lines pointing to a single place, X marks the spot! I could have used * which might indicate more data points, but how that looks is kind of dependent on a person's computer/browser profile). Indeed - we no longer have to assume honesty. It is incredibly unlikely that even if all people were liars, that they would point in such a fashion as to create a point where all the lines cross at the same time.Of course, there is a big problem that is easily overlooked. What happens if my destination's location is the unwitting victim of a common misconception? Everybody thinks they know where it is (and everybody agrees where they think it is), but everybody is wrong in the same way. In my home town, there is a building that looks exactly like this. If I ask for directions to the town hall I am quite likely to encounter a number of people who will point me at this. However, the official council building is located a few miles away.So, if I want to be really careful, I would look to completely different types of evidence that doesn't suffer from the same kinds of errors or problems as people do. Let's go universal, and say that I am trying to find the magnetic north pole - I have so far asked eight people and have got the pattern in the diagram above (I've pretty much circumnavigated the globe to ask for directions!). It is unlikely they are lying, but they might be under a misconception. So each time somebody tells me, I also take a look at my compass. I find that the compass agrees, more or less, with the people each time and so I begin to follow one of the lines. I also look to where the sun rises and sets and make sure that is consistent with me heading to magnetic north. I look for stars, such as the North Star and make sure I'm travelling correctly as per that, and finally I use my knowledge of geography to ensure I am maintaining something of constant correct direction. If I was in London yesterday and Manchester today - I'm doing well because Manchester is closer to the North Pole than London is. I might even get out my GPS equipment, measure shadow lengths at various times and any other creative methods you might think of.I can even continue to circumnavigate the globe making sure that I am creating converging lines of evidence again - only this time...they are independent of each other. One might have certain potential problems, another might have different ones. If they are all pointing in basically the same direction, converging approximately on a point I can increase my confidence with each independent line that I know where the North Pole is.Occasionally, I'll make a measurement that points in a completely crazy direction as being North. This is interesting. It might be that I am using the technique wrong, forgetting to compensate for something (if I'm on a metal ship, a compass could be affected by the metal and start going crazy), or maybe I've just discovered something new and interesting. We'll call these outliers, most of the time they are mistakes and we might not understand how they happen, perhaps we'll explore them later but for now we'll simply discard them. The more outliers we find, the lower our confidence is, and it might even be possible to make some statistical calculations of confidence to work out which is the most likely location what the probability of that is.Having read a multitude of books, read primary literature, conducted simple home tests of my own, spoken personally with scientists who conduct more complex tests, seen various practical applications of knowledge all surrounding the the subject of evolution I am confident that there are multiple independent converging lines of evidence that point to the conclusion that life has changed over time on earth, that all life is related, that the modern synthesis pretty much explains how this all happens, and that it has happened over billions of years. In short (heh) - this is why I have the degree of confidence I have in evolutionary science. Edited by Admin, : Shorten long link.Edited by Modulous, : Culling 2,100 of my babies words.Edited by Modulous, : No reason given.

There are a number of errors in there since I was still editing the post before release. They aren't huge problems, but my 1 in a 100,000 was meant to be 1 in 1,000 for instance, and this obviously impacts the numbers that follow it - I got a little carried away.I'm having issues editing it - they might be related to the reasons it got posted twice rather than previewed once. Perhaps due to its size? I'll leave it alone for now...

I was able to make edits to it, but the length *is* a problem. It's too long for an opening post. If you trim it down to something under 800 words or so then I'll promote it. Hold the original version aside, you'll be able to feed in the rest of it during discussion.As you noted, maintaining the focus on the interwoven web of justifications for high confidence rather than on the details of the individual justifications will be important.If you can't edit it then make a copy of it for yourself and let me know, the I'll delete the contents for you so you can add a new version. I'm using Chrome these days, other browsers only when checking browser compatibility.--Percy

I did some merciless murdering of my words, (nah just kidding - they've been moved into cold storage). It stands at about 900 words now and is just the set-up for discussing the centre piece of my point: independent converging lines of evidence. If you really want - I'll hunt around to take it down to below 800. Either way I'm going to get some sleep.

I sure hope so - I couldn't believe the time on your previous post, and this one is even more ridiculous. Hope you don't have to get up early for work tomorrow.It's looks and reads fine the way it is, I see no need to be a stickler for 800 words. I'll promote it now.

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--	Percy
	EvC Forum Director

Thread copied to the Confidence in evolutionary science thread in the Biological Evolution forum, this copy of the thread has been closed.