Strong atheism is the positive belief that no god exists.
Arguments for strong atheism
The following is an unedited email. This article is a work in progress and will be cleaned up soon.
I call myself an atheist. I reject the very concept of a western-style god, an omniscient, omnipotent, intelligent, aware being which created and was responsible for the universe. I do not call myself an agnostic, one who believes that we do not and cannot know whether there is (or was) such a god. Here's why.
There are two kinds of truth: contingent and logical.
A contingent truth is one whose validity is contingent on other facts which may or may not be true or known. An example is whether there exists intelligent life in a distant galaxy. Since we know, as a proof of principle, that intelligent life exists in our galaxy, and we don't yet understand the conditions that gave rise to it, we may accept the possibility that it could exist in another galaxy. Since we have very little information about conditions in distant galaxies, and we will probably never have sufficient information to answer such a question, the only reasonable answer to that question is that we don't know, and probably never will. A reasonable, fair, and open-minded person must be agnostic on that question.
A logical truth is one whose validity depends only on logic, on the definitions and properties of concepts we ourselves define. An example is whether 2 + 2 can equal 5. It follows from the definitions of 2, 4, 5, +, and = that 2 + 2 can only equal 4, not 5. It is not necessary for a reasonable, fair, and open-minded person to remain agnostic on that question. There is nothing contingent or unknown about it.
As a scientist, I have devoted my career to mastering the only reliable way we have of knowing the universe: the empirical method, the combination of theory and observation propounded by 17th and 18th Century philosophers like Galileo, Locke, Newton, Berkeley, Hume, Kant, and their successors. We construct our understanding by working from the simple to the complex. We understand atoms in terms of elementary particles and their forces, such as quarks, leptons, gluons, and photons. We understand molecules and chemistry in terms of atoms and their interactions. We understand biology in terms of the underlying chemistry and its emergent properties. We understand intelligence in terms of the complex interactions of the underlying neurological or electronic substrate.
Of all the things we know of in the universe, the most complex is intelligence. To posit an intelligence as the creator and driving force of everything else makes no sense, since it would itself require explanation in terms of simpler underlying entities. It makes no more sense than 2 + 2 = 5. It is not incombent upon a reasonable, fair, open-minded person to remain agnostic on that point.