# Comments on Dembski-Marks's "active information."

This is a guest appearance of Erik Tellgren.

I (Mark Perakh) have not contributed anything to this essay and am posting it as a courtesy to Erik.

Here starts Erik’s text:

William Dembski has been one of the most influential contributors to
the Intelligent Design (ID) movement. Among other things, his work has
added the terms *specified information, specified complexity, and
complex specified information* to the basic vocabulary of the ID
movement. These terms are all directly related to the logarithms of
special types of probabilities, e.g. the probability of a pattern of
interest given that it was produced in some way that excludes the
foresight and guidance of an intelligent agent.

In a recent draft manuscript, Dembski and his coauthor Marks extend
the vocabulary with three new terms [1]: *endogenous information,
exogenous information, and active information*. They consider as
given a search space and a fixed subset, called a *target*, that makes
up some fraction ps of the search space. An issue of interest to them
is how to measure how well a search algorithm [2] exploits the
structure of the search problem. Two possible candidates are the
probability *p* that a search algorithm is successful and the ratio
*p/ps.* Readers of Dembski’s previous writings will not be surprised to
discover that Marks and Dembski prefer to log-transform their
probabilities and rename them ‘information’. In equations, their
definitions are

endogenous information = -log_{2}(p_{s}),

exogenous information = -log_{2}(p),

active information = -log_{2}(p_{s}/p).

Continue reading **Comments on Active Information** at Talk Reason