Hi Jane, great question about how to get students to demonstrate
understanding. One I hadn't thought about. Off the top of my head I
would say that they would demonstrate understanding if they knew what
predictions a certain concept would make, which of those predictions
had been tested, and how much evidence there was for the concept (that
evidence would be in the form of accurate/precise predictions).
As for causal knowledge that is a tricky one and one I have wrestled
with because in some ways causes are like those Russian babushka dolls
- causes ended up nested in causes. For example, if we're talking
about causes for amphibian decline and I say low pH is one cause of
declines, have I identified a cause? Somebody could say low pH is not
the cause - it is the form of aluminum that is present at low pH.
Somebody else could say it's not the amount of aluminum of that form
that's in the water that is the cause, it is the aluminum binding to
some receptor inside the frog that is the cause.
So, in theory, pH could perfectly predict amphibian trends and I would
then conclude we have perfect understanding but in fact there could be
an explanation beneath pH where we know almost nothing. So, in my
opinion, prediction is they only way to demonstrate understanding but
understanding is often layered and perfect prediction at one level
wouldn't necessarily imply understanding at another level.
These are really difficult issues and I think it's easy to see them as
esoteric and of not much practical concern but I think ecology has
actually done a pretty poor job of quantifying our understanding and
without that how do we know where to focus our resources? How well do
we understand the effects of invasive species on the distribution and
abundance of native organisms? I actually have no idea. Have we
barely scratched the surface and we should direct more resources at
that question? Do we almost have that question completely sorted out
and so should move on to the next important question? Should we throw
up our arms and say that this is an unanswerable question? Best.
Jeff
PS Sorry for straying so far from the original question
Jeff's comments are good ones. I don't know why all the apostrophes
came through as question marks, but maybe that's appropriate -- these
are difficult issues and I, for one, have more questions than answers.
On one hand, there are certainly examples that demonstrate that
understanding is neither necessary nor sufficient for prediction. On
the other hand, the two are certainly connected. It's been pointed out
that causal knowledge, unlike statistical knowledge, enables us to
predict how a system will behave under interventions. Maybe that helps
-- I don't think you can understand a phenomenon without causal
knowledge. Also, let's look at pedagogical questions. How do we ask
students to demonstrate understanding of concepts?
BTW, I want to clarify a remark I made earlier about chaos. While the
long-term behavior of a system exhibiting chaotic behavior cannot be
predicted in the sense that the time series can't be predicted, we CAN
predict other aspects of its dynamics, such as the parameter values
resulting in different modes of behavior. So maybe before we can
productively discuss the relationship between prediction and
understanding, we ought to clarify what we mean by prediction. How
broadly or narrowly do we want to construe the term?
Best,
Jane
On Thu, Mar 3, 2011 at 7:19 AM, Jeff Houlahan <jeffh...@unb.ca> wrote:
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.
--
-------------
Jane Shevtsov
Ecology Ph.D. candidate, University of Georgia
co-founder, <www.worldbeyondborders.org>
Check out my blog, <http://perceivingwholes.blogspot.com>Perceiving Wholes
"In the long run, education intended to produce a molecular
geneticist, a systems ecologist, or an immunologist is inferior, both
for the individual and for society, than that intended to produce a
broadly educated person who has also written a dissertation." --John
Janovy, Jr., "On Becoming a Biologist"
