Fine-tuning, or fine-tuned universe (SEP link), is the idea that the fundamental properties of our universe appear to be delicately calibrated to allow the existence of life. It has been used as evidence suggesting the universe is created by an intelligent designer.
I suggest the fine-tuning argument for design is false because it puts life in a special position while analyzing the universe objectively. People usually do not challenge it because we ourselves are life, it is logically special to us. However, this perspective-specific significance does not mean life is somehow objectively important to the universe.
Fine-Tuned History
I have 2 parents, 4 grandparents, and 8 great-grandparents. This number keeps multiplying. 50 generations back, the theoretical upper bound for the number of my ancestors is about 10^15, way above the total number of humans ever lived. Of course, there would be significant overlaps in this mega family tree. At this scale, calling it a family web would no longer be a joke. Nonetheless, even with overlapping, it still means going back far enough, say around 1000AD, my direct ancestors would cover a significant portion of the world population.
My existence is the result of all those people’s reproductive success. That means any historical event that affected the lives of a moderate number of people must have unfolded exactly the way it did for the creation of me. If Alexsander lost the battle of Gaugamela, or Genghis Khan failed to unite the Mongol tribes, or Columbus did not reach the New World in 1492, I would not be here.
Why stop there? It can go even further and be more disturbing. For my existence, it is not enough that all my ancestors successfully produced offspring, they had to produce the exact offspring. Meaning in each case the exact sperm had to fertilize the exact egg. Couple this with the exponential growth of my family tree the chance of my existence is unfathomably small. Yet, here I am. This is either a statistical miracle or, an unknown force has guided every aspect of the past to ensure my existence.
History is fine-tuned for me. The odd is too improbable to ignore.
In All Seriousness….
I can imagine how people would react if I tell them history is fine-tuned for me. They will say I am unbelievably egocentric and narcissistic. Why would history care if you are produced or not? Something could very well happen differently causing you not to be born. Big deal? More importantly, if the past is fine-tuned for you, am I just a by-product of that fine-tuning? I can use the same argument from my perspective and say history is fine-tuned for me instead of you. Safe to say it is not going to be well received.
Foreseeing these criticisms I decide to modify that argument a bit. I need more allies on this. So instead of focusing on the immediate “me”, extend it to “us” or “my kind”. Depending on how inclusive I want to be, that could mean humans, or life, or conscious beings, or complex physical systems, or maybe something even more general. On the other hand, to keep the probability low, extend the history further back. Consider the entire universe: its initial conditions and how the fundamental parameters were set. Voila, now we have the fine-tuned universe. It is still the same egocentric and narcissistic argument. But this time, anyone I can expect to discuss it with is on my side. Since we are all “life”.
Perspective Consistency is the Key
I am not suggesting being egocentric is inherently wrong. On the contrary, I think indexicals such as “I” or “now” are naturally central to first-person reasoning (see my core argument). However, when analyzing history or the fundamental constants of the universe, we typically do not want the analysis to be perspective-specific. We usually want to get rid of any egocentrism in the logic, i.e. we reason “objectively”. With this impartial stance, the special logical status of me/us is no longer justified. The key is, first-person reasoning and “objective” reasoning should not mix. Fine-tuning, like other anthropic paradoxes, is caused by such a mix.
If we reason from our natural first-person perspective, it is valid to focus on “I” and ask questions such as “how do the fundamental constants affect me”. Egocentrism is warranted here because “I” am unique from my own perspective. It is also valid to ask why I find all past events and the parameters of this universe are compatible with “my” existence. The answer is obvious. The existence of the self is a prerequisite of reasoning from its perspective. From “our” perspectives, “we” must exist. The world ought to be in a state compatible with “us”. It is a trivial tautology.
Criticism of the Weak Anthropic Principle
That idea is the Weak Anthropic Principle (or how WAP should be interpreted). It is the correct and complete answer. However, it only answers questions formulated from our first-person perspective.
Many find the weak anthropic principle deeply unsatisfying. Some argue it is not a “causal” answer. Some think it discourages us from finding a physical explanation. These criticisms arise because people confound the question from the first-person perspective with the objective ones. The weak anthropic principle is mistakenly used to answer both. In fact, we need a different answer for non-perspective-specific analysis, an impartial causal model that explains the constants, i.e. we still need a scientific explanation. Whatever that explanation turns out to be, it should be answering a question not focusing on life/our kind.
The fine-tuning argument is false because it askes the perspective-specific question “why is everything compatible with our existence?” then demands a non-perspective-specific answer. Effectively it assumes life is objectively significant to the universe. That is why it often leads to teleological conclusions.
Who I am is Not a Sampling Outcome
The most prevalent misinterpretation regarding the WAP is to treat it as an observation selection effect (OSE), i.e. treating the fact that I exist as this observer as the result of some selection with survivorship bias. This is so common that OSE is often seen as equivalent to the anthropic principle. I am not aware if anyone has explicitly expressed objections to it.
However, as explained in my core argument, perspective centers are primitively identified. If Caesar asked “why am I Caesar?” there is no logical explanation to it. It is irreducible. In contrast, OSE explains the perspective center “I” as the outcome of a sampling process. As discussed in Part 2, 3, and 4, this is a sign of mixing reasonings from multiple perspectives. Treating “I” as a sampling outcome is to reconcile the conflict caused by this mix: the logical significance to the first-person and the objective indifference towards it.
An Answer to a Non-existing Problem
Since the OSE interpretation also mixes reasoning from two different perspectives, it considers fine-tuning a legitimate problem that needs to be answered. To explain the improbable existence of “me” or “us”, a sampling outcome subject to survivorship bias according to OSE, the population must be huge. It suggests there is a good reason to believe there are a near-infinite number of universes each with different properties. Only in universes compatible with my existence can I exist. Therefore it is not a surprise that we find our universe has the fundamental constants conducive to life. In short, life is extremely improbable if there is only one universe, so there ought to be many more. This is the essence of the multiverse explanation of fine-tuning.
Obviously I disagree with this response with reasons explained above. It mistakenly creates a reference class for indexicals such as “I” or “this world”. However, here I am not arguing that there is no multiverse, or multiverse theories are unscientific. I am simply arguing my “seemingly improbable existence” cannot be used to suggest multiverses do exist. In another word, fine-tuning is not valid evidence to increase one’s confidence in the multiverse theories.
Fine-Tuning Argument For Design
I have already made my case against fine-tuning. Since it is a logical truth that the universe is compatible with our existence, there is no need to explain it with the idea of a designer, or God. However, my argument is merely uninterested in God’s existence. It is not arguing against it either.
If one believes in God’s existence, and further believes God favors humans or life, then life’s logical significance is warranted. Because with these assumptions, life is objectively important to the universe. Only then fine-tuning becomes a valid idea. Obviously these assumptions also explain the cause of fine-tuning. This belief system justifies the problem and simultaneously gives a perfect answer to it. It is logically self-consistent. However, this argument cannot be used to increase one’s credence about those assumptions.
Furthermore, not all religions think God particularly favors humans or life. According to these religious world-views, fine-tuning would remain to be an invalid idea. However, it can still have a self-consistent belief system that acknowledges the existence of a transcendental supreme being.
Heaven and Earth are indifferent, all things are considered like straw dogs.
Tao Te Ching
To me, beliefs about the existence of a designer ultimately depend on faith rather than reason. The fine-tuning argument can neither be used to increase nor decrease one’s subjective probability in such matters. If one can reason rationally.
2020/08/01: Leslie’s Firing Squad is perhaps the most often used rebuttal to the WAP answer. In 7.1 I present a novel counter to it. It demonstrates the issue with the fine-tuning argument for design from a different angle.