I have heard the term “The Church of Reason” to refer to our modern disposition toward rationality and science. Some thinkers are upset by this analogy, claiming that rationality is fundamentally distinct from a religion. In some ways this is true: for instance, rationality does not entrust a single institution or treatise with control of its truth (though some sects — I mean branches — come very close to a blind trust of scientific consensus). However, I sometimes get the distinct impression of a further belief, however never explicitly stated, that logic and science are not just the latest way, but the way to discover truth.
A succinct criticism from within the logical discipline describes my thoughts well. I quote:
If I see a coin come up heads twenty times in a row, I’m going to use the power of induction to predict that the coin is biased towards heads. Induction tells me that, the more something has happened in the past, it’s more likely to continue to do so in the future. I trust induction because induction has worked for me before.
Somewhere out there in mind-space is someone who believes in anti-induction: each coin flip of heads convinces him that the coin is biased toward tails. Anti-induction tells him that, the more something has happened in the past, the less likely it is to do so in the future. If asked why he trusts anti-induction, he exclaims: “Because it’s never worked before!”
This delightful morsel is so much more than an idle curiosity to me. Please do not mistake me for taking the surface interpretation: I do not claim that induction and anti-induction are equally valuable. But the anti-induction hypothetical illuminates, in an entertaining way, that belief in induction is circular. Observe that our unwavering trust in logic rests upon induction.
In this modern age it is sometimes easy to forget that there was a time when most of humanity was deeply religious. Humans of every intellectual prowess saw “God did it” as a sound explanation (allow me to assume omnipotent monotheism for the sake of argument). Some theorized about how God thought, what he looked like (whether that was a legitimate question), what would appease him, what actions would cause him to create rain or not. Instead of conjuring thoughts of mockery, I would like the reader to put him or herself into one of those minds. You are not stupid; you are deeply immersed in a cultural belief system. It rains — you think back upon the actions of your town recently to try to determine why it must have done so; determining this is of the utmost importance. You may even engage in scientific practices, coming up with hypotheses and testing them: if I sing to one, but not both, of my children at night, the probability that God will be pleased is increased. But this science is based upon a faulty foundation: a whole host of different phenomena could be attributed to “God will be pleased”, and the method is not scientific by modern standards. It is still superstition. What I am putting forth is that the very process of modern science and reasoning may be considered superstition — or perhaps some yet-uninvented term to describe our primitive thinking — to the cultures of the future. Maybe, like the character above, what we are doing is analogous to the search for truth, but we’re missing the point.
But we can make predictions! I will grant that we can make better predictions than traditional religious belief systems used to. I am no scholar of religion, but I can at least imagine a tribe understanding that the fire spirit, who loves the taste of dry wood, will duplicate himself to any nearby dry wood. This makes a prediction as well (at the time of this understanding, it had not yet been observed that he would duplicate himself from Honto’s wood to Jumara’s wood). Nowadays we have only a more accurate idea of the spirits, and we call them by silly names like Boson and Gluon. (I would like to stress that we cannot yet predict anything perfectly. E. T. Jaynes argues that the stunningly accurate probabilistic results of quantum electrodynamics do not count as perfection; i.e. that interpreting the quantifiable uncertainty of its predictions as fundamental to nature rather than to the theory is a boneheaded arrogance.)
Speaking of quantum theory, in the last century we have come across physical laws with an unsettling interpretation problem. Quantum systems are defined in terms of measurement amplitudes, and measurement occurs when a quantum system interacts with a classical system. Of course, if quantum theory wishes to be foundational, the term “classical system” must refer to a mathematical interpretation of a system, not a specific, real system, for every system ought to be a quantum system. So now we are talking about the point of measurement being one interpretation interacting with another — we are speaking on the mathematical and the physical level at the same time. Philosophically, this is utter nonsense. A dominant viewpoint among physicists is that of instrumentalism, summarized by Feynman as “shut up and calculate”. In other words: our logical and intuitive explanations fail us, but the mathematics work out. We have stumbled upon a stunningly accurate mathematical theory with fuzzy, unintelligible edges; could this not indicate an impedance mismatch between our logic and reality? Electrons do not obey classical physics, though large ensembles of them converge on classical physics. Why should we assume nature obeys classical logic; perhaps only large ensembles of truths converge on classical logic? Indeed, the calculation structure of quantum amplitudes seems to be logic-esque, with rules at least for conjunction and disjunction. Maybe the barrier lies not in the transition to a classical system, but the transition to classical logic. Perhaps, if we could only think differently, there would be no barrier.
In order to be heard, I am arguing from a position that we just have the laws of logic slightly wrong, and that a successor would take the same form merely with different laws. I do not necessarily believe this — my inner mathematician wishes it, for it would be comfortable and familiar — but it is simply the most concrete way, the smallest step I can take, to cast doubt upon the logical absolute.
You and I are immersed in a culture of reason, just as many generations of humans before us were immersed in a culture of theism. I cannot simply show you an alternative way to see the world; I am as clouded by these conceptions as anyone of our time. I do not wish to replace your foundation, just erode it. I wish to illuminate the possibility that we may, still, be looking at clouds, and not at the stars.
So many philosophical pseudo-debates focus on the existence or non-existence of this or that “thing”. Pop-skepticism is at odds with most sects of Christianity about the existence of a God; many skeptics, somehow oblivious of the hypocrisy in which they engage, argue simultaneously that claims must be supported with evidence and that there must be no God. I engaged fleetingly with the university’s skeptics society in a debate about the existence of the electron, in which I argued that the electron was a mathematical tool that enjoyed the same level of existence as a number, and not so much existence as…
Fortunately for me, I did not have to complete the above thought, as the debate was on facebook so I was permitted not to respond once the level of abstraction exceeded me. Rather than the inevitable fate of a face-to-face debate on the subject — in which I would make a fool of myself for failing to possess a well-collected, self-consistent argument, my opponents permitting me to exit the arena now having failed to disrupt their conceptual status quo — the debate fizzled out, and they will probably not remember of their own volition that they had even engaged in it. It is all for the better that my medium has changed, since after some time spent meditating on the question, I have come across something I have not been able to distill into a snappy epigram.
To a “standard model” logical mind, and even to the working mathematician who has not studied logic, existence is a straightforward concept. One can ask whether a mathematical object exists with some property, and assume without argument that one is asking a reasonable question with a yes-or-no answer. However, in the world of mathematical logic — the only logical world whose paradoxes I can comfortably resolve — the notion of existence is rather more slippery. There are the standard objects which one can prove to exist from the axioms, and there are — or perhaps I should say, there are not — objects whose existence is contradictory. But there is a neglected middle class. These objects _____ whether or not you choose to exclude the middle.
The Twin Prime Conjecture (TPC), a famous question still open today in 2011, conjectures that there are infinitely many numbers p such that both p and p+2 are prime. One of these pairs is called a “twin prime”, for example 5 and 7, or 179 and 181. There are many who believe TPC is true, some who believe TPC is false, but among logicians (who crave this sort of result), many believe TPC is “independent of the axioms.” Let us explore the consequences of this latter belief. To be concrete (insofar as such a word can mean anything in such matters), let us suppose that TPC is independent of “ZFC”, the Zermelo Frankel axioms with the Axiom of Choice, the axioms of choice (no pun intended) for popular set theory.
It would be helpful to be reminded of what exactly ZFC is. Aside from the deep fantastic worlds of intuition inhabiting many mathematicians’ minds, it is merely a set of 9 statements about the world of sets. For example, “if two sets have the same members, then they are the same set”, and “given any set, you may form the subset of elements satisfying a particular property”. These are stated in rigorous, precise logical language, so by formal manipulation we can exclude the subtleties of meaning that would abound in any English presentation of these axioms. Logicians like to say that a proof is nothing more than a chain of formal logical sentences arranged according to some simple rules; this view has spread since the advent of programming languages and computerized mathematical assistants.
If TPC were true, then given any number, you could count up from that number and eventually reach a twin prime. If TPC were false, then there would be some number, call it L, above which it would not be possible to find any twin primes. However, since TPC is independent (because we have supposed it), then we know we cannot prove it either way. It may be true, or it may be false; whether there is a third option is too deep a philosophical question to explore here. We may be able to count up from any number and find a twin prime, but we will never be sure that we will not arrive at a point after which there are no more. Or there may in fact be an L above which there are no more, but we shall never be able to write L as a sequence of digits. Again, whether these two comprise all possibilities is not a matter capable of absolute resolution.
There can be no proof that L exists, so, like God to the skeptics, it must not exist. By their own standard, this conclusion is not justified, for, by our assumption, there is no evidence in favor of its nonexistence either. Indeed, we may safely believe in L; if a contradiction would arise from its use, then we could leverage that contradiction to provide a proof that there are infinitely many twin primes, thus TPC would have been provable. After centuries of cautious hypothesis of what would happen if L did exist, we may begin to treat L as any other number. As the ancient Greeks’ unease about the existence of irrational numbers has faded, so too would ours. The naturals would become: 1, 2, 3, 4, 5, … L, L+1, …. We will have answered questions about L, for example it is greater than one million, because have found twin primes greater than one million.
This all happens consistently with the proof that the set of natural numbers is made up of only the numbers 1, 2, 3, 4, 5, …, for that proof does not mean what we think it means. We cannot enumerate all the natural numbers in a theorem; that proof only states that the set of natural numbers is the smallest set made up of zero and successors of elements in that set. If we can actually find a twin prime above any number, but merely not know it, then we might claim L cannot be the successor of any element in this set. But this claim is false, because L is clearly the successor of L-1! L, whether or not or ___ it is one of the familiar numbers, manages to sneak its way into the smallest set containing zero and successors. It is not the set of numbers, but the language about numbers that can be extended by this independence of TPC, and L is not logically distinguishable from “regular” numbers. It is a symbolic phenomenon. But so, too, are the familiar numbers. The only difference is we have chosen to say that zero exists.
Arguments are in the business of increasing certainty. They begin with some assumptions, make some claims, support the claims with evidence, and then reach a new conclusion which, if you agree with all the steps, you should now accept as part of your belief system. We are born as blank slates who know nothing, and over the course of a lifetime, we make and read arguments until, by the time we die, we know a great many things with great certainty.
Opportunities for deep, life-changing learning are rare and must be cherished. Therefore, when we come across an argument whose assumptions are agreeable but seems to be heading in a direction contrary to our beliefs, we read with increased interest in hopes of being proved wrong. After all, if the argument is sound and comes to a conclusion that is contradictory to what we know, then, having seized the opportunity, we have discarded some nonsense and become more enlightened.
By this time, you have noticed that this is satire (I should hope!). But what am I making fun of? A simplistic interpretation is that I am lamenting the irrational way people treat arguments, that they need to be more willing to question themselves if they want a belief system founded in truth. Or perhaps they need to be more logically-minded, to prevent themselves from adopting such self-contradictory systems of belief in the first place. It doesn’t really matter what is wrong with people, as long as whatever it is explains why they will not accept my sound logical argument.
Now I am clearly making fun of someone you know. This person has a strong personality and holds as a core belief that most people are stupid. They write or speak passionately, they stay close to the scientific doctrine, they take pride in their certainty. While their arguments are convincing, they lack a certain respect for those who disagree, and it ends up limiting them from a more complete world-view. We all know this person, and, thankfully, acknowledging that we know someone like this releases us from the possibility of being this person.
The author is being subtly disrespectful now. He is trying to make me wonder whether I fall into this category, and in doing so, attempting to put himself above me. And this paragraph is even more disrespectful, taking on the voice of the reader, assuming he can predict his or her thoughts. Fortunately, he has failed, for one couldn’t say the reader was thinking anything beyond reading at the time.
At least I have not said anything that threatens your beliefs. That would merely serve the disengaged brain to produce a disinterested Ctrl-W or a polarized, indignant comment. Before I can convince you of any new truth, I have to convince you to engage with the question. An active mind taking a question seriously will produce a far more convincing effect than any amount of eloquent word-barrage. My goal was this: if the page was still in focus by the time you reached this paragraph, your mind would be curious and primed.
Now for my argument: what could I convince you of?