I've spent considerable time now trying to come up with a way to make this post interesting and, after much reflection, have finally decided that may be impossible. A few days ago, a young earth creationist on twitter "agreed"to a debate (I say "agreed" because like a man afraid of becoming a husband, he did not set a date). In preparation for that, I thought I'd use this post to lay a little groundwork.
In arguing anything, and especially with those given to fallacy, it is important to be clear in what we mean. Too often we run up against people who quite literally have no idea what they are talking about. Other times, they'll resort to equivocation, shifting meaning as it suits them. (In all fairness, I suspect a great many people guilty of equivocation fail to realize they are; frequently they are just repeating something they've been told) With that in mind, I thought it best to start with a few definitions.
Atheism is the position of having no belief in god(s). The etymology of the word has been parsed so many times that I won't do so here. Suffice it to say that it supports this definition. In addition, defining atheism this way has some advantages. It is a broadly inclusive definition, encompassing both outright denial (There is no god) and cautious skepticism (There is insufficient evidence for god).
This definition is also in line with the default position of philosophy and the null hypothesis of science. Because this is a point that is often overlooked by creationists, I'll explain it further. In science, a hypothesis is tested against what is known as the null hypothesis. The null hypothesis essentially states that whatever being tested is not the case. If the evidence to support the proposed hypothesis is insufficient, the null hypothesis is accepted. Similarly, the default position is the one accepted when a belief lack support. Typically, these are negative statements, as is our definition.
(Some of you may note that the null hypothesis may be formed positively. However, to avoid the cry that we are claiming certainty, we will stick with the negative formation)
Finally, and perhaps most important to a debate, defining atheism as I have nicely splits the issue in two. A person either believes in god or does not believe in god. There is no in between here, no grey area for insufficient knowledge. And while this may upset some people who are afraid of the atheist label, it is both in line with the concept of agnosticism and beneficial to debate. (For those of you in need of convincing, ask yourself this: If you don't know whether an oncoming car will run a stoplight, don't you still form a belief? I certainly do)
Well then, that's one definition out of the way. Sadly, even this relatively brief explanation is sufficiently lengthy, so I'll hold off on any further definitions. As an aside, the creationist who agreed to the debate is looking more likely to back out. Until I get proper confirmation, I'll return to my regular rantings on the impossibility of god.