This is a digest of how various researchers in biology and astrobiology have explored questions of what defines living organisms—definitions based on functions or structures observed in organisms, or on systems terms, or on mathematical conceptions like closure, chirality, quantum mechanics and thermodynamics, or on biosemiotics, or on Darwinian evolution—to clarify the field and make it easier for endeavors in artificial intelligence to make progress. Current ideas are described to promote work between astrobiologists and computer scientists, each concerned with living (...) organisms. A four-parameter framework is presented as a scaffold that is later developed into what machines lack to be considered alive: systems, evolution, energy and consciousness, and includes Jagers operators and the idea of dual closure. A novel definition of consciousness is developed which describes mental objects both with and without communicable properties, and this helps to clarify how consciousness in machines may be studied as an emergent process related to choice functions in systems. A perspective on how quantization, acting on nucleic acids, sets up natural limits to system behavior is offered as a partial address to the problem of biogenesis. (shrink)

Abstract: This paper explores the relevance of themes from Wittgenstein's Tractatus Logico-Philosophicus to the ongoing discussion of metaphysical nihilism. I set out by showing how metaphysical nihilism is of paramount importance for cosmological arguments. Metaphysical nihilism is the position that there might have been nothing. Two conflicting intuitions emerge from a survey of discussions of metaphysical nihilism: Firstly, that metaphysical nihilism is true, and secondly, that formulations of the position are somehow unclear or nonsensical. By considering formalizations of philosophical language, (...) the second intuition is sharpened, while the first intuition is given expression through the Tractarian distinction between what is said and what is shown by our symbolism. I conclude by exploring and rejecting objections to making metaphysical nihilism a scientific, rather than a philosophical question. (shrink)