It sounds somewhat plausible that everything that could have happened did happen – even if it did not in our universe. The many world theory of Hugh Everett suggests that every time a possibility does not pan out in our universe, it gives rise to a parallel universe where it does.
The many worlds theory thus revolves around what is, in fact, possible. It is not a coincidence that much speculation on this has as its starting point trigger mechanisms related to radioactive decay. As radioactive decay is unpredictable at least with our current state of knowledge, per definition a trigger mechanism based on radioactive decay implies the possibility of both result A and result B. Both possibility A and possibility B will thus exist in a state of superposition according to generally accepted quantum mechanics theory. The famous Schrödinger’s cat thought experiment assumes a release mechanism for the poison based on radioactive decay exactly because of the unpredictability of the result. The cat is dead and not dead until wave function collapse (in Schrödinger’s theory) because both states are possible, and unpredictability reigns. In the many worlds theory there is no wave function collapse and hence both possibilities will continue to exist – but in different universes.
That every possibility will play out in some universe does not mean that every imaginable possibility will play out. It may be that some parallel universes will not know gravity and that hence a brick may float freely even in Earth-like conditions. It might be that gravity is not an absolute law of nature and floating bricks might be the most natural thing in some parallel universe ruled by other laws of nature. Yet, this does not mean that the floating brick is possible on our Earth, and hence not even in the many worlds theory the imminence of the fall of a brick on Earth would give rise to a parallel universe in which the brick would float. We must assume that parallel universes born by possibility could arise only if such possibility arises under the laws of nature of our universe.
In which situation, then, do the laws of nature create possibility – when do the laws of nature not dictate results, when is nature not deterministic? Radioactive decay mechanisms are the most unproblematic examples. In the book ‘Our Mathematical Universe’ Max Tegmark makes an immense conceptual leap from the non-deterministic nature of radio-active decay to an assumption of much broader indeterminism when he suggests that when he is making a right or a left turn on his bike it is not predetermined and that hence both options will come into being in parallel universes. The basis of Tegmark’s assumption seems to be free will. He seems to imply that he has the freedom to choose and hence both options will materialise. Yet, most physicalists will say that his choice is predetermined. A computer put in the same situation would make a reasoned decision based on inclination, ability and previous experience. Only if one could imagine a perfect balance of factors in favour of either option a physicalist would perhaps concede that his computer model would need a random element in order to be able to break possible deadlocks. Buridan’s ass, positioned at the exactly same distance from two equally appealing haystacks, is the best-known illustration of this sort of indecision. But the physicalist would assume that such a random element to break a tie would be of very, very limited application. In fact, our personal experiences probably substantiate both the random element and the rarity thereof. All of us have known situations where we say ‘what the heck’ and choose randomly. But those situations are few and far between and not all are genuine. Some are in the final analysis dictated by our nature and our experience. Tegmark’s example of going right or left is very likely not an example of random decision.
If free will would be limited to absolute randomness it could then be argued that physicalists have largely won. The scope for free will would be very narrow. Yet, there is another way of looking at it.
Physicalists tend to assume that only one of several options is possible. Hence, the computer model will give only one response. But what quantum mechanics teach us is that several states are possible at the same time, superposition, and consequently that reality must not be limited to just one path. As soon as a probabilistic element (as with radioactive decay) is present, superposition is present and two realities arise – and persist according to the many worlds theory. Possibility is born of probabilistic randomness as well as of the absolutely random!
Probability as a conditioning factor chimes well with human nature, or spirit more generally. Humans and other creatures tend to be not entirely predictable, tend not to be absolutely deterministic. We may have preferences, but how these preferences play out in specific situations is rarely clear, even to us ourselves. That is the unique feature of spirit. We may prefer red to blue in eight out of ten cases, but in each individual case of choice it cannot be predicted with certainty whether red or blue will be chosen. Whenever a human must choose and is in doubt probability enters the field, and, if we believe quantum mechanics and Hugh Everett, superposition will then arise, and both options will live in parallel universes no matter which choice we as unique individuals actually make. A parallel version of us will live the discarded choice.
Yet, perhaps free will is not entirely free. Perhaps the probability that goes with conditioning does play a role. Nevertheless, when we are offered the choice between two credible narratives, between two realities, it would seem that we are, indeed, free to choose between them! And this is true every time we have to choose. Every time we bring the baggage of conditioning, and every time we can choose to leave it behind and choose blue rather than the more appealing red. In this way free will can defy probability. Every time we are in doubt about a choice we can choose against our conditioning, because every choice is subject to one-off probability.
In human affairs it is, in fact, hard to imagine probability without free will. We will possibly conform to norm over time, but the fascinating thing is that free will seems to allow us to select the extent of application of our conditioning in each individual case. Every time we must choose we make a conscious choice between two realities that exist independently as a result of superposition.
Do we take this to mean that we can defy the odds of conditioning in the long run? That may be the great ethical question. Can we, without being conditioned to do good, do more good than our conditioning would make probable? Perhaps probability makes for choice, and choice serves as a corrective to probability. A kind of closed loop, you may say. Choice might not alter a person’s basic properties, but might be a fire that can purify or pollute them. If every choice is a real choice does it not follow that the cumulative result of our choices is indeterminate as well? Depends on us? Ah, the beauty and mystery of free will!
 As computers, indeed, have.
More on this topics in blog posts:
- A Theory of Free Will, 24 October 2015
- Free Will and Wave Function Collapse, 30 October 2015