I mentioned previously that the Scottish skeptic, David Hume, took this reliance on induction to task in the 18th century. Hume asked how it could be empirically justified to rely on the future being like the past. How do we justify taking observed cases as logical indicators for future cases? How can I logically connect the fact that fire has burned me in the past with the belief that it will burn me again if I continue to put the flame to my hair.
It may be very tempting at this point to take the easy looking road to irrational conclusions and say "The answer is obvious. It has always been that way in the past, so there is no reason to expect any different in the future." Now, I agree that we shouldn't expect future cases to be any different than past cases, that we should rely and bank on the future being like the past. We should assume the uniformity of nature, but not for the reason that it has always been that way in the past. To that reasoning, Hume would respond that our past experience of nature only gives us the logical right to say that nature has acted a certain way thus far, but our past experience gives us no logical right to say that nature will act similarly in the future.
Well, if we can't depend on past experience to give us a logical foundation for induction, then maybe we can depend on probability. In other words, because nature has been uniform so much in the past it is very probable it will continue to maintain its uniformity in the future even if it isn't 100% certain. The problem with this reasoning is that probability is only a helpful indicator of future events in a world where the future is like the past. Appealing to probability just pushes the question back one more step. If we can't first justify our reliance on nature's uniformity then we can't appeal to probability for anything let alone to justify our reliance on nature's uniformity. We end up just begging the very question we first asked. Probability relies on nature's uniformity which still leaves induction in need of a rational foundation.
In order to rely on the future being like the past we have to make an assumption. We have to step into a realm that is independent from experience and empirical knowing and assume what cannot be scientifically verified which is that nature is uniform. So if experience cannot logically justify our reliance on the future being like the past and we can't appeal to probability without being circular, how do we provide a rational justification for assuming that nature is ordered and uniform instead of random and arbitrary?
Now, at this point no one is saying that nature is not uniform and no one is claiming that we should not expect and rely on the future being like the past. All we are trying to do is provide a rational basis to say and do those things. But, because we all already assume the uniformity of nature and live our lives like we know the future is going to be like the past, do we really need to go through the trouble of asking these tough philosophical questions? I would say certainly yes. The reason is because this is a fundamental question about reality that everyone depends on even without realizing it. It is what all our reasoning takes for granted.
Our reliance on the assumption that nature is uniform manifests itself in every single thing we do in life. When I get up and cook breakfast in the morning, I rely on an assumption that the future will be like the past in order to cook my eggs in the cast iron starting with low heat and plenty of butter. If the future is anything like the past, if nature is uniform, the result will be a perfectly fried egg. I assume the uniformity of nature in order to know that my personal identity is the same today as it was yesterday and I will still like my eggs cooked in plenty of butter with a slightly runny yolk, just like yesterday morning. Simply put, there is not one area of life that could function if we did not assume the uniformity of nature. So, it stands to reason we should have some kind of rational justification for what everything in life assumes, relies on and takes for granted.
We have already established that the answer to this necessary problem is not one the physical world can provide. This is both frustrating and devastating to the materialist, whose worldview is built on the assumption that all that is can be confined to the physical world and nothing outside of it need be considered because it doesn't exist. The materialist sees the world as a closed physical system with questions that can be answered and verified empirically. Nothing exist that lies outside empirical knowing. Chesterton takes a jab at those who claim to be talking scientifically when they claim to have scientific verification that an apple will always fall from a tree because of a Law of Nature. He says, "They do really talk as if they had found not only a set of marvelous facts, but a truth connecting those facts... It is not a 'law,' for we do not understand its general formula. It is not necessary for though we can count on it happening practically, we have no right to say that it must always happen." He goes on to say that those who think in materialistic terms assume to have an inner synthesis that they do not posses. It lacks that inner synthesis precisely because it limits reality to the physical world that is empirically verifiable. Yet, the problem of induction that sits behind all reasoning and knowing whatsoever can only be addressed by stepping outside that which is known empirically and stepping into the metaphysical, that which is beyond empirical knowing. In order to do that though, one has to be operating within a worldview that allows for a reality that includes more than the physical world. Sorry materialist, but I do believe that was the last yarn pulled from the sweater your grandmother knit you back in the Enlightenment.
So we see, at its most fundamental point, it is necessary to look outside the confines of our physical existence in order to make anything within the confines of our physical existence the least bit intelligible. We all already live like this is true, though many of us probably haven't thought about its implications for how we personally view and understand the world. The implications are, of course, enormously significant and can't be expressed better by this writer than what has already been penned by Chesterton,
It is possible that God says every morning, "Do it again" to the sun; and
every evening," Do it again" to the moon. It may not be automatic necessity that
makes all daisies alike; it may be that God makes every daisy separately but has
never got tired of making them... The repetition in Nature may not be mere
recurrence it may be a theatrical encore. Heaven may encore the bird who laid an
egg. If the human being conceives and brings forth a human child instead of
bringing forth a fish, or a bat, or a griffin, the reason may not be that we are fixed
in an animal fate without life or purpose, It may be that our little tragedy has
touched the gods, that they admire it from their starry galleries, and that at the end
of every human drama man is called again and again before the curtain.