Saturday, April 16, 2005

LBDES: Lack of Awareness of Perceptual Component of Abstractions

As part of the Looking Back Down Explorer Street series of posts... again, a bunch of notes on a theme, and kinda abstractly presented.

The following is about a potential problem with our knowledge or awareness, or lack thereof, of the nature of the abstractions we reason with.

Abstractions can divide up the world according to how we perceive it, rather than according to any real divisions that exist out there in the world. To effectively reason with abstractions we need to understand how much our own perception contributes to the nature of abstractions we are reasoning with.

Here are some examples of things that have a strong perceptual component. Colors are a classic case. The colors we perceive are based on objective features of the world, but the manner in which we divide the world up into the different colors is a property of our perceptual/cognitive systems and not the objects themselves. To give another example, the reason that we call something analogue or digital, or descrete or continuous, is somewhat surprisingly often perceptual, and not to do with the things themselves.

Here is an example that shows how this lack of awareness can impact on the effectiveness of our reasoning. This example involves the notion of species, and the full details are here. Evolution works by the gradual transition between forms by means of natural selection. Some people incorrectly think that a 'species' is a collection of things of a particular type out there in the world, and that through evolution we should find intermediates between species in the fossil record. And since there aren't such intermediates, then a conclusion that can be drawn is that evolution is wrong.

But in fact, since there is gradual change in the fossil record there are no natural sharp boundaries where we can say these things are of species X and these are of species Y. Our notion of 'species' is ultimately a construction. The notion of species has to do with how we cut up the world, not how the world is. There are no intermediates between species because when we find a fossil that is not clearly in one or another species that we've created, we always decide to put it into one or the other. In other words, the notion of species we have created does not allow for intermediates between species.

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