The worldview that includes western science has inadvertently misled us by a long-held (though often unstated) belief in the idea of LaPlace’s Demon. The Demon is one of several imaginary creatures of science that are used to illustrate points or concepts, often to students. This particular demon may be more demonic than the others. If I remember correctly, LaPlace’s Demon is a creature with a perfect knowledge of the present and an equally perfect knowledge of the past. And so, we believe, he should have a perfect knowledge of the future, being able to predict any event; the Demon gives determinism the form of a mythical being. Determinism says that the imperfection of our knowledge is the only reason that we cannot fully predict the future. Granted, there is no reason to think that our “dataset” will ever be complete or our knowledge ever perfect, but our admiration for this demon says a lot about our basic assumptions. To many of us, prediction, not explanation, is the central theme of science. But what if nature is not like this? What if the fundamental behavior of the universe is to be partly unpredictable? We can still approach our universe scientifically and generate increasingly accurate and inclusive explanations as our understanding grows. The purpose of science is to describe and explain the universe around us, whether the phenomena, the events, are fully predictable or not. I think this is a realistic view, but it does make things a bit more difficult.
Can we predict the next speciation event? No. Can we know all the features of a mature plant when we sow the seed and observe the seedling? No. Will we ever be able to fully predict the weather? I’m doubtful, but that doesn’t make meteorology any less of a science. The surprising behavior of weather is something worth explaining in itself. Absolutely exact forecasts may be impossible by the very nature of weather. Our satellite imagery allows us to see a hurricane forming and we have a good idea of the general direction of its path and the strength and direction of associated winds, but these often change dramatically, whimsically (there is a strong element of whimsy in the universe, I think). Perhaps we lack the environmental details necessary to predict just where the storm will go next. Or maybe not. Maybe some of the behavior of big storms is simply not predictable.
Jack and Cy add: “But one should not take these words to mean we live in a world of chaos; this would preclude doing science. There is a level of predictability in a whimsical universe. The earth circles the sun and tides rise and fall in regular cycles. A hurricane that starts in the Atlantic Ocean will not suddenly appear in a different ocean. If a white oak acorn is planted, a white oak tree will grow, even though its exact form cannot be known. Should white oak, a species, undergo speciation, the products would look like (and also not look like) white oak, but just how is beyond human knowledge.” Perhaps because species and individuals are only partly “pre-formed” – the “whimsical” aspects don’t happen until they happen.
Imagine a human zygote, a newly fertilized egg, with DNA from each parent, cytoplasm, mitochondria and other cellular components from the egg. We could have detailed knowledge of this zygote’s ancestry. We could also have a profound understanding of this zygote at the molecular level, including its genetics. There are some things, clearly linked to genetics, that we could know – her sex, her eye color, various diseases she may have inherited. But would we ever be able to fully predict what she’ll be like at fourteen? At forty? A reductionist, for whom the explanation for everything resides in the molecular minutiae, might say yes, eventually, but at this time our knowledge is imperfect. Given even the most detailed information, I say no, we will never be able to fully predict the outcome of her development for the very reason that the phenomenon is emergent. It hasn’t happened yet and is not fully predictable based on earlier states. The outcome (the being) will depend on the girl’s development (the becoming) and will be vastly more than the sum of her parts, her DNA, cells and organ systems. All of these molecular, cytological and anatomical parts share vast numbers of interactions. But even if LaPlace’s Demon had a perfect grasp of all interactions, past and present, the complete outcome would remain unknowable until it exists. The Demon is mythical because new, surprising properties appear from interactions at smaller scales, but they are not describable based solely on information from those smaller scales.
This last paragraph applies to such controversial subjects as stem cell research. Biologically, a single cell of a multicellular organism is alive in the sense that it is taking in nutrients and oxygen; it is metabolizing and dividing through mitosis. However, single mammalian cells and zygotes are not free-living bacteria or algae and they are not able to survive outside of a life-support system, be it the greater mammal body or a petri dish. Zygotes, cell clusters and embryos are just that; these stages are far too early in development to manifest the properties of Homo sapiens.
A few centuries ago early biologists believed that fully formed adult humans, homunculi, existed in miniature form within single cells. Scientists of the time imagined that these little beings inhabited sperm cells and directed their own gestation and development, nurtured within the womb. With technological advances, including better optics, scientists found that there were no little people within sperm calls, but the idea of a “vital force” directing development of living things didn’t go away. For modern genetics and molecular biology, the “vital force” or the “ghost in the machine,” the source of biological “purposive change” was apparently moved out of imaginary miniature people residing in sperm cells, down into the smaller units of molecules, especially DNA. This was hardly an improvement. There is no little person inside of a set of chromosomes, or inside of a zygote, or inside of a ball of cells organizing itself to become a vertebrate embryo. A zygote is not independently alive. It has the capacity, given proper internal and external conditions, to grow into a free-living human organism, but this can only happen through the phenomenon of ontogeny, or development. The outcome is partly predictable, but only partly.
This non-determinism, this surprising, whimsical, unpredictable aspect of nature has important implications beyond frustrating some scientists. It may be one of our most important “hints” in understanding evolution and many other natural phenomena. Another important “hint” includes the self-organization that is obvious during development. Self-organization and unpredictability are related to the idea of emergent properties – more complex forms or levels of organization arise from simpler forms, and the complex levels can’t be fully predicted or even described in terms of the simpler levels. This generalization applies to many events in nature, from convection currents and hurricanes to developing humans. In spite of his complete and perfect knowledge, LaPlace’s demon would be unable to prognosticate because the past and present don't fully foretell the future.