While you are reading this post you may not have realised, or noticed, that the universe only burst into existence, last Thursday at 900am (god always works to office hours). Also at this time you sprang into being, fully formed and complete with a lifetime of memories that did not occur. When the Earth appeared, in a thrice last Thursday, it was imbued with all the patina of 4.5 billion years of existence complete with fossils cunningly fashioned. Although your navel is superfluous, its presence is a testament to god's mischievous nature. You may surmise that you are reading the mewling screed of a raving madman. But I assure you I'm quite sane, medication permitting, and I have a certificate signed by my psychiatrist, with the hackneyed name of Professor Mugumbo to prove it. That being the case, I have to ask you in all honesty- can you disprove that everything, in this vast universe of ours, didn't just pop into existence last Thursday?
I am being disingenuous as I'm fully aware that you can't refute the proposition. Just like solipsism, the concept of 'Last Thursdayism' is both unverifiable and unfalsifiable by the scientific method. On fundamental principle, it is impossible to subject the concept to empirical scientific rigour as the 'data' is considered to have been arbitrarily created to mimic the reality of great age at every level of observable detail. And indeed, there is nothing in the concept of 'altered reality' which is incompatible with the laws of logic.
You may form the opinion that this sort of reasoning is the exclusive preserve of ivory tower professional philosophers who are paid to contemplate such bollocks. And to be frank I'm sympathetic to those who espouse such a view. However, the idea of 'Last Thursdayism' is put forward to make a serious point against fundamentalist beliefs. There are groups of fundamentalist Christians, although admittedly not all Christians, who fervently believe the Earth to be 6,000 years old in spite of the myriad of contrary evidence; good solid evidence from multiple sources in happy accord with a universe of billions of years old. The fundamentalist counters by saying that their god has planted the evidence to give the impression of an aged Earth in order to test the faith of the believer. We would have to concede that god has a sense of humour, after all.
If the fundies can argue for a world of only 6,000 years old, what is stopping someone arguing that the universe, and all it entails/entrails, was created last Thursday, or five minutes ago for that matter? You may consider that the concept of 'Last Thursdayism' quite silly. If you hold this view, then by extension, a 6,000 year-old Earth seems ridiculous in spite of its impeccable logical credentials.
For me, the greatest flaw in the 'Young Earth' theory can be revealed by a simple intellectual tool, called Occam's razor. I introduced the concept of Occam's razor in a previous post- you can check it out, here. Occam's razor states that where several explanations are available, the simplest is generally the best. The law is also known as the law of parsimony and contends that you should never posit more than is necessary to arrive at an explanation for a given phenomenon. In modern parlance, we would say: "keep it simple". If we apply this cardinal rule to our problem, the most likely explanation is that the universe is billions of years old and what we see is the development of natural processes obeying natural laws over eons. The alternative, the ‘Young Earth’ theory is immeasurably more complex to contemplate. There is no gradual developmental process but the sudden materialisation of everything current plus everything that went into the making. It also leads to the belief in deities. How could the infinity complex facade be constructed in an instance without the intercession of a very powerful sentient entity? Thus we observe another layer of hyper-complexity contrary to Occam's sharp-edged tool.
Thus, gentle reader sleep sound in your bed tonight, knowing that you are not a carcass filled with lies but a fully fledged human with a history and a past lasting well beyond last Thursday, probably.