Reasonableness is a matter of degree. Beliefs can be very reasonable (Japan exists), fairly reasonable (quarks exist), not unreasonable (there's intelligent life on other planets) or downright unreasonable (fairies exist).There's a scale of reasonableness, if you like, with very reasonable beliefs near the top and deeply unreasonable ones towards the bottom. Notice a belief can be very high up the scale, yet still be open to some doubt. And even when a belief is low down, we can still acknowledge the remote possibility it might be true.How reasonable is the belief that God exists? Atheists typically think it very unreasonable. Very low on the scale. But most religious people say it is at least not unreasonable (have you ever met a Christian who said 'Hey, belief in God is no more reasonable than belief in fairies, but I believe it anyway!'?) They think their belief is at least halfway up the scale of reasonableness.Now, that their belief is downright unreasonable might, in fact, be established empirically. If it turned out that not only is there no good evidence of an all-powerful, all-good God, there's also overwhelming evidence against (from millions of years of unimaginable and pointless animal suffering, including several mass extinctions - to thousands of children being crushed to death or buried alive in Pakistan earthquake, etc. etc. etc.) then it could be empirically confirmed that there's no God.Would this constitute a 'proof' that there's no God? Depends what you mean by 'proof'. Personally I think these sorts of consideration do establish beyond any reasonable doubt that there is no all-powerful all-good God. So we can, in this sense, prove there's no God.Yet all the people quoted in my last blog say you cannot 'scientifically' prove or disprove God's existence. If they mean prove beyond any doubt they are right. But then hardly anything is provable in that sense, not even the non-existence of fairies.

~ Stephen Law

[At the beginning of modern science], a light dawned on all those who study nature. They comprehended that reason has insight only into what it itself produces according to its own design; that it must take the lead with principles for its judgments according to constant laws and compel nature to answer its questions, rather than letting nature guide its movements by keeping reason, as it were, in leading-strings; for otherwise accidental observations, made according to no previously designed plan, can never connect up into a necessary law, which is yet what reason seeks and requires. Reason, in order to be taught by nature, must approach nature with its principles in one hand, according to which alone the agreement among appearances can count as laws, and, in the other hand, the experiments thought in accordance with these principles - yet in order to be instructed by nature not like a pupil, who has recited to him whatever the teacher wants to say, but like an appointed judge who compels witnesses to answer the questions he puts to them. Thus even physics owes the advantageous revolution in its way of thinking to the inspiration that what reason would not be able to know of itself and has to learn from nature, it has to seek in the latter (though not merely ascribe to it) in accordance with what reason itself puts into nature. This is how natural science was first brought to the secure course of a science after groping about for so many centuries.

~ Immanuel Kant

A miracle is a violation of the laws of nature; and because firm and unalterable experience has established these laws, the case against a miracle is—just because it is a miracle—as complete as any argument from experience can possibly be imagined to be. Why is it more than merely probable that all men must die, that lead cannot when not supported remain suspended in the air, that fire consumes wood and is extinguished by water, unless it is that these events are found agreeable to the laws of nature, and for things to go differently there would have to be a violation of those laws, or in other words a miracle? Nothing is counted as amiracle if it ever happens in the common course of nature. When a man who seems to be in good health suddenly dies, this isn't a miracle; because such a kind of death, though more unusual than any other, has yet often been observedto happen. But a dead man’s coming to life would be a miracle, because that has never been observed in any age or country. So there must be a uniform experience against every miraculous event, because otherwise the event wouldn't count as a ‘miracle’. And as a uniform experience amounts to a proof, we have here a direct and full proof against the existence of any miracle, just because it’s a miracle; andsuch a proof can’t be destroyed or the miracle made credible except by an opposite proof that is even stronger.This clearly leads us to a general maxim that deserves ofour attention:No testimony is sufficient to establish a miracle unless it is of such a kind that its falsehood would be more miraculous than the fact that it tries to establish. And even in that case there is a mutual destruction ofarguments, and the stronger one only gives us an assurance suitable to the force that remains to it after the force needed to cancel the other has beensubtracted.

~ David Hume