I am sufficiently irritated by D.J. Grothe's repeated reference to skepticism as a "worldview" that I will probably be motivated to write a blog post about it.
There is a growing ambiguity caused by overloading of the term "skepticism" on different things--attitudes, methods and processes, accumulated bodies of knowledge, a movement. To date, there hasn't really been a capital-S Skepticism as a worldview since the Pyrrhonean philosophical variety. A worldview is an all-encompassing view of the world which addresses how one should believe, how one should act, what kinds of things exist, and so forth. It includes presuppositions not only about factual matters, but about values.
The skepticisms worth promoting are attitudes, methods and processes, and accumulated bodies of knowledge that are consistent with a wide variety of world views. The methods are contextual, applied against a background of social institutions and relationships that are based on trust. There is room in the broader skeptical movement for pluralism, a diversity of approaches that set the skepticisms in different contexts for different purposes--educational, political, philosophical, religious. An unrestricted skepticism is corrosive and undermines all knowledge, for there is no good epistemological response to philosophical skepticism that doesn't make some assumptions.
Trying to turn skepticism into a capital-S Skeptical worldview strikes me as misguided.To my mind, what's most important and useful about skepticism is that it drives the adoption of the best available tools for answering questions, providing more guidance on how to think than on what to think, and on how to recognize trustworthy sources and people to rely upon. There's not a completely sharp line between these--knowledge about methods and their accuracy is dependent upon factual knowledge, of course.
I think the recent exchanges about the Missouri Skepticon conference really being an atheist conference may partly have this issue behind them, though I think there are further issues there as well about the traditional scope of "scientific skepticism" being restricted to "testable claims" and the notion of methodological naturalism that I don't entirely agree with. Skepticism is about critical thinking, inquiry, investigation, and using the best methods available to find reliable answers to questions (and promoting broader use of those tools), while atheism is about holding a particular position on a particular issue, that no gods exist. The broader skeptical movement produces greater social benefits by promoting more critical thinking in the general public than does the narrower group of skeptical atheists who primarily argue against religion and especially the smaller subset who are so obsessed that they are immediately dismissed by the broader public as monomaniacal cranks. The organized skeptical groups with decades of history have mainly taken pains to avoid being represented by or identified with the latter, and as a result have been represented by skeptics of a variety of religious views in events of lasting consequence. Think, for example, of the audience for Carl Sagan's "Cosmos" and his subsequent works, or of the outcome of the Kitzmiller v. Dover trial.
In my opinion, the distinction between skepticism and atheism is an important one, and I think Skepticon does blur and confuse that distinction by using the "skeptic" name and having a single focus on religion. This doesn't mean that most of the atheists participating in that conference don't qualify as skeptics, or even that atheist groups promoting rationality on religious subjects don't count as part of the broader skeptical movement. It just means that there is a genuine distinction to be drawn.
(BTW, I don't think atheism is a worldview, either--it's a single feature of a worldview, and one that is less important to my mind than skepticism.)
Previous posts on related subjects:
"A few comments on the nature and scope of skepticism"
"Skepticism, belief revision, and science"
"Massimo Pigliucci on the scope of skeptical inquiry"
Also related, a 1999 letter to the editor of Skeptical Inquirer from the leaders of many local skeptical groups (Daniel Barnett, North Texas Skeptics, Dallas, TX; David Bloomberg, Rational Examination Association of Lincoln Land, Springfield, IL; Tim Holmes, Taiwan Skeptics, Tanzu, Taiwan; Peter Huston, Inquiring Skeptics of Upper New York, Schenectady, NY; Paul Jaffe, National Capitol Area Skeptics, Washington, D.C.; Eric Krieg, Philadelphia Association for Critical Thinking, Philadelphia, PA; Scott Lilienfeld, Georgia Skeptics, Atlanta, GA; Jim Lippard, Phoenix Skeptics and Tucson Skeptical Society, Tucson, AZ; Rebecca Long, Georgia Skeptics, Atlanta, GA; Lori Marino, Georgia Skeptics, Atlanta, GA; Rick Moen, Bay Area Skeptics, Menlo Park, CA; Steven Novella, New England Skeptical Society, New Haven, CT; Bela Scheiber, Rocky Mountain Skeptics, Denver, CO; and Michael Sofka, Inquiring Skeptics of Upper New York, Troy, NY).
UPDATE (December 1, 2010): D.J. Grothe states in the most recent (Nov. 26) Point of Inquiry podcast (Karen Stollznow interviews James Randi and D.J. Grothe), at about 36:50, that he has been misunderstood in his references to skepticism as a "worldview." This suggests to me that he has in mind a narrower meaning, as Barbara Drescher has interpreted him in the comments below. My apologies to D.J. for misconstruing his meaning.