Wednesday, December 20, 2006

Evidence: Lots of Questions

Off memetics for a while. I've been focusing a bit too much, I think, on a subject that will only be part of a chapter on how different groups can manipulate science because of a priori assumptions external to science. The following post is, however, influenced in part by my thoughts on memetics and its popularity.

Lately, I've been having fleeting thoughts about the nature of evidence, since one "theme" of the book will be the different ways of "knowing" the world (common sense, philosophy, science, religion, etc.) and how they interact with modern debates.

In the next few posts, I'll lists some of the questions that I'm hoping to "answer" to some extent. (I haven't quite gotten to that level of arrogance that will permit me to believe that I will answer millenia-old questions.) I'd love to have your feedback.

BIG QUESTION NUMBER 1: What does the "absence of evidence" mean beyond the dictionary definitions?

Much is made of the absence of evidence for supernatural beliefs, BUT do we humans really abandon any "faith" or "theory"- secular or religious - when faced with an absence of evidence?

What do I mean? Evolutionary theory crashes into an absence of evidence when we try to explain the Cambrian Explosion, the apparent arrival of most of the major phyla in a very brief period of time, geologically speaking. The absence of evidence for precursors to most of the species arriving at this time is explained away.

Fossilization, after all, is an extraordinarily rare event, even more rare for soft-bodied species. We presume that the Cambrian Explosion represents not the sudden emergence of thousands of species, but the evolution of the shell so that more species are being fossilized than before. This is a highly reasonable explanation of the absence of evidence based on what we know about fossilization and one I tend to prefer. However, there really is NO EVIDENCE for the thousands of soft-bodied species that would have existed prior to the Cambrian Explosion if this explanation is correct.

Intelligent design proponents use this to attack evolution. Absence of evidence, G-d tinkering with the program, and all that. Most of "us" science-loving types, even the religious ones, say the I.D. criticism is hogwash. Although we don't have the evidence, we "know" why we don't have it or wouldn't.

So, what does absence of evidence mean in the end? When and how do we know when to abandon ship and when to accept a reasonable explanation for the absence of evidence?

2 Comments:

Anonymous dan from ideasandhowtheyspread.com said...

So, what does absence of evidence mean in the end? When and how do we know when to abandon ship and when to accept a reasonable explanation for the absence of evidence?
That's easy: when the evidence for the reasonable explanation of why the evidence is not there is greater than the reasons that we would expect the evidence to be there were our theory true.

5:46 PM  
Blogger Melinda Barton said...

Which leads me to "how do we know what evidence will support X?" Easy to answer with some things. Not so easy with others. There'll be a post on that soon. Just fleshing out my thinking here before I tackle the (insert scary music here) the book outline and proposal!

8:14 AM  

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