An egg is fertilized and begins to divide forming an embryo which continues to develop into a fetus. Beneath that level of development the egg is comprised of molecules which are in turn comprised of atoms which are in turn made up of sub-atomic particles. Is it the case "life" is built into the equation on some specific level or do we have a definitive answer to this question?

On the human level much ado is made politically about when it is morally repugnant to abort.

Is there a special quantum function that delineates between animate and inanimate matter? Are there a special class of quarks that are actually alive?

  • I hope I followed the right stairway down from the fetus to the quark. It's been a long time since I paid any attention to the order of things and formulated this question from an aging and therefore suspect memory. Jul 25, 2017 at 17:50
  • I think the note about abortion is actually separate from the primary question you are asking. I don't think that pro-choice people would say that the fetus "does not have life," but would instead argue that the cells of the fetus, which are alive, are still a part of the woman. Pro-life people, on the other hand, would say that the fetus is a separate human being from the woman. Both groups recognize that the cells of the fetus are alive (have "life"), but the debate is about how that life is classified (just another part of the woman, or a new and distinct human).
    – elmer007
    Jul 25, 2017 at 18:49
  • There are a variety of pro-choice arguments. One — associated with Mary Anne Warren — argues that, even if a fetus is alive (and a distinct entity from the pregnant woman), it is not a "person," i.e., does not have moral standing. So there's nothing morally wrong with destroying it.
    – Dan Hicks
    Jul 25, 2017 at 19:36
  • Another — associated with Judith Jarvis Thompson — argues that, even if a fetus is alive, and a distinct entity, and a person, the pregnant woman still has a right to bodily autonomy and integrity, and therefore has a right to refuse to support the life of the fetus, and therefore has a right to abort it. But both of these are separate from the question about reductionism.
    – Dan Hicks
    Jul 25, 2017 at 19:38
  • @elmeroo7: You are correct, I was reaching for an example of the kind of reductionism had in mind when framing the question and not intending to turn the question on a political earlobe. Jul 25, 2017 at 21:21

3 Answers 3


You're asking about reductionism in biology. If you read the introduction to that article, you'll see a distinction between ontological, methodological, and epistemic reduction. Ontological reduction can be true even if methodological and epistemic reduction are false: it can be true that living organisms are "nothing more than" certain arrangements of fundamental physical entities, and yet this relationship is so complex that it's practically impossible for us to reduce biology to chemistry, much less fundamental physics.

As I understand it, in medicine and bioethics the beginning and end of life are usually defined in terms of brain activity. Ontologically, is brain activity "nothing more than" certain arrangements of fundamental physical entities? Maybe. But notice that we don't determine time of death by examining the state of such entities. So someone might argue that we determine time of death by examining the state of a biological organ. On this view, life might be ontologically reducible, but not methodologically or epistemically.

  • That was an excellent reference Dan. I am very interested in how and or if life makes the climb from the quantum to the molecular level and if we can retrograde in positing a specific type of living sub-atomic combination. Jul 25, 2017 at 21:18
  • After having read your reference material in its entirety I realize my question hasn't been adequately addressed. I'm not so much concerned by which philosophical scope I must peer thru as I am with how deeply I must look. Although it dances around the issue on several floors I'm still left wondering if I can anticipate a quantum connection to life somewhere therein? Jul 26, 2017 at 2:52

Your search presumes there is one official definition of life, perhaps scribed upon stone tablets in nice differential equation notation. In reality, the word has given philosophers great trouble defining. Virtually all philosophers agree that a human is alive, as is a dog, as is a fish. Most philosophers generally agree that rocks are not alive. However, there is not a solid consensus regarding where the line should be drawn beyond those very easy examples.

Science itself has multiple definitions, but the most popular specifies a set of criteria for something to be alive:

  1. Homeostasis: regulation of the internal environment to maintain a constant state; for example, sweating to reduce temperature
  2. Organization: being structurally composed of one or more cells – the basic units of life
  3. Metabolism: transformation of energy by converting chemicals and energy into cellular components (anabolism) and decomposing organic matter (catabolism). Living things require energy to maintain internal organization (homeostasis) and to produce the other phenomena associated with life.
  4. Growth: maintenance of a higher rate of anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter.
  5. Adaptation: the ability to change over time in response to the environment. This ability is fundamental to the process of evolution and is determined by the organism's heredity, diet, and external factors.
  6. Response to stimuli: a response can take many forms, from the contraction of a unicellular organism to external chemicals, to complex reactions involving all the senses of multicellular organisms. A response is often expressed by motion; for example, the leaves of a plant turning toward the sun (phototropism), and chemotaxis.
  7. Reproduction: the ability to produce new individual organisms, either asexually from a single parent organism or sexually from two parent organisms.

That would probably be the closes to an accepted definition of life that can be had from a scientific approach.

One can choose to go beyond that, and define one's own criteria for life. There's no rule against it, no thought police that will imprison you for your crimes. One could define life in a way which uses the language of quantum mechanics to do so. However, if you use an existing word like "life" and apply a new meaning to it, you can expect to have to defend your definition, for we typically like to keep the meanings of words as clutter-free as possible, and "life" is already quite cluttered.

  • It has been years but I remember something along religious lines about irreducible complexity. I don't think it was addressed at precisely this type of query but I am thinking it may apply here. Jul 26, 2017 at 9:26
  • I waited too long to edit but I was trying to add that we assume there are connections between levels of inquiry such that logic would dictate this should also be the case where animate material is concerned. I am just wondering if the relevant difference between animate and inanimate is found in a specific chemical ingredient or maybe a nuanced expression of energy or some combination thereof, or neither? But it would help to know on which level some sort of animation begins. Jul 26, 2017 at 9:39

The lines we draw between "animate" and "inanimate" or between "conscious" and "not conscious" are entirely arbitrary. At this stage of human development, we simply don't know enough about the very nature of life and consciousness to make such distinctions in a non-arbitrary fashion.

See also my answer to Does consciousness depend on our five senses? where I address how consciousness can be modeled in a layered fashion, like a Matryoshka doll. The lowers layer of consciousness would be the smallest particles imaginable and the highest layer of consciousness would be the universe itself. Individual humans and human collectives would both be somewhere at the intermediate level, along with all other life on this planet.

It is mostly a mixture of genetic and cultural prejudices that makes us empathize more with some forms of consciousness and less with others. That's why abortion is sacrilege in some cultures and normal in others... or why some people eat cats while others treat them like children.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .