1.1: The interconnectedness (self-consistency) of science

It was once thought that there were aspects of biological systems that transcended physics and chemistry, a presumption known as vitalism. If vitalism were correct, it would force a major revision of chemistry and physics. As it turns out vitalism is, apparently, incorrect. The world described by the sciences is like an extremely complex crossword puzzle (→) where the answer to one question must be compatible with the answers to all other questions.^[25]Alternatively, certain questions, and their answers, once thought of as meaningful can come to be seen as irrelevant or meaningless and not part of the puzzle. For example, how many angels can dance on the head of a pin no longer impacts scientific explanations.

Over time, biological processes from the metabolic to the conscious have come to be seen as consistent with physicochemical principles. What makes them different is their complexity. They are the product of evolutionary processes, processes influenced by unpredictable events that influence subsequent events and stretch back in an uninterrupted “chain of being” over billions of years. Biological systems are composed of many types of molecules that interact in complex ways. All this means is that while biological systems obey physicochemical rules, their behavior cannot be predicted based on these rules.

It appears that all life we know of is related. All known organisms are modified (evolved) versions of a “last common universal ancestor”, known as LUCA. It may well be that life, as we know it, is unique in the Universe. If other kinds of life are possible, we have no evidence for them. We do not know the “general rules” governing life because we only know one type of life, that found on Earth.

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