Re: [ECOLOG-L] Hypothesis Testing in Ecology

[Jeff Houlahan]

In response to Jane?s comments ? I admit that understanding and  
prediction are not the same thing but they are much more closely  
related than most people appreciate, in my opinion.  I would go so far  
as to say that prediction is a necessary if not sufficient condition  
of understanding.  So while it is possible to predict without  
understanding (as in Jane?s Babylonian?s example ? although I knew  
nothing about the Babylonians and their ability to predict, I have no  
doubt that?s true) I think it is impossible to demonstrate  
understanding without prediction.  In fact, I realized that I can?t  
come up with a definition of understanding that satisfies me without  
talking about prediction (none of the on-line definitions that I found  
worked very well for me).  My definition of understanding would be   
?The ability to make specific predictions based on a general  
description of how the world works.?  Now, I guess it?s possible that  
somebody could understand how the world works but not be able to make  
any predictions but that means that they can?t demonstrate their  
understanding.  In my opinion, understanding that can?t be  
demonstrated has little(no?) value because I can?t distinguish that  
person from all the people who claim they have understanding but have  
none.
My above definition leaves room for ?thinking? you understand when you  
don?t, in situations where you make good predictions for the wrong  
reasons.  But, even here prediction is critical because we will only  
detect our mistake when we try to make a new prediction and our  
?understanding? leads us astray.  That is, the only evidence of our  
mistake will be poor prediction.
So, my original claim was not that understanding and prediction are  
the same thing but that understanding cannot be demonstrated without  
prediction.  And predictions have to better than we would make by  
chance. And the only way to evaluate that is through some measure of  
probability/likelihood.  Best.

Jeff Houlahan
PS I would be interested to hear any examples where understanding can  
be demonstrated without prediction.