Let's take a stab at it.
I'm a gnostic atheist and I think that the belief there is no god is justifiable. But before we go into that, let's get the basic straight here. What I observe most commonly in this debate are the following points being repeated over and over again. From the atheist side we have:
1. Proving a negative is impossible.
2. You don't need to disprove what has never been proven in the first place.
While I agree that any bare assertion doesn't need to be disproven to justify disbelief in it, I think that where such a disproof is possible, it should be provided.
On the theist side we have two common evasions:
1. But you can't know that for 100%, therefore you don't "know" it.
2. That's not what god is/does.
Therefore, the validity any argument against the existence of god must rely on agreed upon principles governing the subjects such as "knowledge", "certainty" and "god". To that end, I'll start with the groundwork regarding what it means to have "certain knowledge".
A commonly accepted tenet of science is that it is impossible to be 100% certain of anything, which is why when we talk of certainty, we talk of reasonable certainty. So, the quibble that "unless you are 100% sure, you can't know it" is nonsensical. As long as you are reasonably certain, then that margin of error is not a deterrent to knowledge. The criteria for reasonability is a bit subjective, but it is based on the weight of logical arguments and actual evidence for or against it.
If a proposition has no evidence or reasoning for or against it then I'd rightly be agnostic about it - belief in it being another matter altogether. For example, it is possible for a subspecies of horses to have developed a bone protrusion on the forehead in shape of horn and then for the species to go extinct without leaving any fossil record - at least, it doesn't go against the principles of evolutionary biology. However, there is also no evidence that such a thing ever existing either. Therefore, I'm agnostic about unicorns.
On the other hand, if a proposition has no evidence for it, but existing body of knowledge contradicts it, then you can gnostically deny it. For example, we don't have any evidence for the existence of winged horses. But we do know that the changes required to the species' morphology would be extreme and would run contrary to the principles of evolutionary biology. Which is why I gnostically disbelieve in Pegasus.
So, taking the most generic definition of god - as a conscious, immaterial entity - I find that there is no evidence for the existence of such an entity and all logical arguments for its existence have been shown to be flawed over and over again. On the other hand, our current knowledge indicates that consciousness is a function of complex networked systems like a brain and cannot exist independent of it. So the idea of a conscious entity without the necessary complex hardware, much less being immaterial altogether, runs contrary to what we currently know. Therefore, our current knowledge on the matter is evidence against the existence of that entity.
Interestingly, the more specific this god gets, the more evidence piles up against its existence. When multiple actions are attributed to the particular god, then all the facts indicating alternate causes for those actions or that those actions never took place become evidence against its existence. Which is why a generic, vaguely defined and ever-changing definition of god is much harder to disprove than the god of any specific religion.
I'm a gnostic atheist and I think that the belief there is no god is justifiable. But before we go into that, let's get the basic straight here. What I observe most commonly in this debate are the following points being repeated over and over again. From the atheist side we have:
1. Proving a negative is impossible.
2. You don't need to disprove what has never been proven in the first place.
While I agree that any bare assertion doesn't need to be disproven to justify disbelief in it, I think that where such a disproof is possible, it should be provided.
On the theist side we have two common evasions:
1. But you can't know that for 100%, therefore you don't "know" it.
2. That's not what god is/does.
Therefore, the validity any argument against the existence of god must rely on agreed upon principles governing the subjects such as "knowledge", "certainty" and "god". To that end, I'll start with the groundwork regarding what it means to have "certain knowledge".
A commonly accepted tenet of science is that it is impossible to be 100% certain of anything, which is why when we talk of certainty, we talk of reasonable certainty. So, the quibble that "unless you are 100% sure, you can't know it" is nonsensical. As long as you are reasonably certain, then that margin of error is not a deterrent to knowledge. The criteria for reasonability is a bit subjective, but it is based on the weight of logical arguments and actual evidence for or against it.
If a proposition has no evidence or reasoning for or against it then I'd rightly be agnostic about it - belief in it being another matter altogether. For example, it is possible for a subspecies of horses to have developed a bone protrusion on the forehead in shape of horn and then for the species to go extinct without leaving any fossil record - at least, it doesn't go against the principles of evolutionary biology. However, there is also no evidence that such a thing ever existing either. Therefore, I'm agnostic about unicorns.
On the other hand, if a proposition has no evidence for it, but existing body of knowledge contradicts it, then you can gnostically deny it. For example, we don't have any evidence for the existence of winged horses. But we do know that the changes required to the species' morphology would be extreme and would run contrary to the principles of evolutionary biology. Which is why I gnostically disbelieve in Pegasus.
So, taking the most generic definition of god - as a conscious, immaterial entity - I find that there is no evidence for the existence of such an entity and all logical arguments for its existence have been shown to be flawed over and over again. On the other hand, our current knowledge indicates that consciousness is a function of complex networked systems like a brain and cannot exist independent of it. So the idea of a conscious entity without the necessary complex hardware, much less being immaterial altogether, runs contrary to what we currently know. Therefore, our current knowledge on the matter is evidence against the existence of that entity.
Interestingly, the more specific this god gets, the more evidence piles up against its existence. When multiple actions are attributed to the particular god, then all the facts indicating alternate causes for those actions or that those actions never took place become evidence against its existence. Which is why a generic, vaguely defined and ever-changing definition of god is much harder to disprove than the god of any specific religion.
