What is Life?

Hi, Mosassam.Welcome to EvC!I think the point everyone is trying to get across to you is that defining "life" really is only a semantic issue, and nothing more.Generally, biologists define "life" with an arbitrary set of criteria that are usually formulated such that the set of things the particular biologist wants to consider "life" get included, while everything else gets excluded. Later biologists may latch on to these definitions and defend them dogmatically, but that’s neither here nor there as far as I’m considered.We currently have no evidence for the existence of a sort of essence or property that distinguishes what we call "life" from what we don't call "life." Currently, we can only describe life based on a few superficial characteristics like self-replication or growth, none of which has been found to be unique to whatever group of things we define as life.So, it seems that life is just the co-occurrence of multiple distinct factors that can be found in isolation or in partial combinations outside of what we commonly call life. This does not seem to offer much opportunity for life to be a distinct property or essence.But, this is just more semantic nonsense, I suppose.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Straggler. If you are ever very clear on this, I would take it as evidence that you are out of touch with reality. But, since the people who study viruses are generally thought of as biologists, and since the study of viruses is parallel to the study of "real" living things in virtually every way, I think you're safe categorizing biologists as de facto proponents of viruses as life-forms, although they may or may not formally argue one way or the other until they're blue in the face.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, AOk. Which means... what, exactly?The fact remains that many things that do not fit the definition of "life" are still more similar to things that are defined as "life" than other things that are not defined as "life" (e.g. a virus is more like "life" than it is like a grain of sand).What do you do with things that match five of the seven pillars, or four, or six?Assigning things to discreet categories doesn't make the gradients between them magically disappear.Edited by Bluejay, : virus example and some cosmetic changes.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, AOk. First, you can't really complete 12 grades without getting a diploma: if you didn't get a diploma, it means you didn't complete at least 1 grade.Second, if people who've completed 12 grades are not necessarily more capable of handling the job than people who've only completed 10 grades, then there is no meaning to completing 12 grades beyond that arbitrarily assigned to it by the arbiter. That is, the diploma holds meaning only because you, the employer (or the law that you're abiding by), say it does.Likewise, in defining life, we're not just looking for something to which we can assign meaning: we're looking for something that has meaning beyond what we assign to it. Clearly, the diploma has no such meaning in your example, so it is not a good analogy for things that actually hold meaning.----- At what point does a pile of bricks become a brick house?
When the last brick is put into place?
When the mortar dries?
When the electrician approves the wiring and the water main is turned on?If you were showing off your 75%-completed house, and you said to your friends, "look at my new house!"---would you be justified in using the term "house"? I wouldn't make a fuss about it.And then, when the brick house is completed, how many bricks have to fall out of the west wall before we have to stop calling it a brick house?
If a tornado took a chunk out of the garage, would you have to revert to calling it an "organized pile of bricks"?"Brick house" is not all that clearly defined in relation to "pile of bricks," so this is yet another example of a pair of terms that are only distinguished insomuch as we choose to distinguish them.----- And then what? Treat them like "not life"? Consider them the equivalent of rocks and sand? Or acknowledge that they fit somewhere between rocks and "life," and thereby reject the idiot classification that has us claiming that "life" is discreetly and distinctly different from "not life"?Actually, virologists treat viruses just as if they were "life." They study their behavior as if they were "life." They study their physiology and genetics as if they were "life." They study their evolution as if they were "life." In fact, biologists consider people who study viruses to be a type of biologist.This raises the question of why we defined "life" to exclude viruses in the first place. Clearly, that definition hasn't had much effect on how we treat them; also clearly, that definition doesn't prevent them from being more like "life" than like other things that are "not life."This is what a biologist means when they argue about the definition of "life" being unclear: not that it's impossible to cobble some things together into a workable definition, but that the definition doesn't really hold much meaning in terms of how things function, behave or evolve.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, AOk. But the context of your analogy was hiring, so none of these other meanings are relevant to your analogy.----- Okay, you obviously didn't understand what I wrote. I know this because the example you provided is not an example of the thing you were trying to defend, but an example of the opposite option.Assigned meaning is meaning that doesn't exist until we define it to exist. This is opposed to real meaning, which is meaning that exists independent of a definition that we assign to it. Anytime you define something based on a series of attributes that are not always correlated with each other, the meaning is assigned, and not real.----- Would you say viruses are more similar to things in the category "life" or to things in the category "rocks, sand and other minerals."

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, Philip.Welcome to EvC!First, you might be interested in learning the formatting codes that we use here:If you type [qs]This is a quote box[/qs], you get this: You can also put [qs=Name of quoted person] instead of the [qs] to get this: That ought to help you out some.There's also a "peek" button at the bottom right of each message. You can click on that to see what codes were used for different formatting styles.----- You suspect wrong.I agree with Jar that "complexity" is a nearly useless word from a scientific standpoint, but I'll use it here just for the sake of argument.Evolution doesn't take place on a gradient of complexity from "simple" to "complex": evolution takes place across a large number of gradients and other axes of variation, such as "body size, small to large," "finger length, short to long," "digestive system compartmentalization," etc. The interactions of all these gradients make a wide diversity of organisms that are not very easy to arrange on a basic gradient from "simple" to "complex. Some lineages indeed show a trend toward increasing complexity. But, equally many show a trend toward decreasing complexity. And, by far the majority of lineages show a combination of both.For example, you could argue that the brain has become more complex in the lineage that went from basal mammals, to basal primates, to monkeys, to apes to humans. But, at the same time, you could also argue that the digestive system and the teeth have become less complex in that same lineage. In fact, the teeth may have repeatedly vacillated between more complex and less complex over time, depending on how you define "complex."----- But, evolutionists only believe that this is the case for evolutionary lineages that are more complex than their ancestors. Evolutionists do not think that all evolutionary lineages have increased in complexity over time.For example, look up "scale insect": these are insects that, as adults, lose all of their extremities and resemble a flat scale on the bark of a tree. Related insects and "more primitive" insects have legs, antennae, eyes and wings. In terms of limb diversity, scale insects are less complex than their evolutionary ancestors.Once again, some lineages have become more complex, some have become less complex, some have alternated between becoming more complex and becoming less complex, and some have become more complex in some ways and less complex in other ways. This is what we mean when we say there is no directionality.However, I fear that we've moved a considerable distance away from the topic of this thread, and perhaps we should be finding a way to get back to the discussion of the question, "What is life?"Edited by Bluejay, : Half a sentence was missing.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, GDR. You've subtly changed "directional" to "directed." As Jar explained upthread, "directional" refers to a sustained direction of change in evolutionary lineages. This we can clearly rule out.Consider stick insects (a.k.a. phasmids; order Phasmatodea). Primitive insects evolved wings, and basal phasmids retained wings. Some lineages of phasmids, however, lost them. Then, some members of these wingless lineages re-evolved wings.Such back-and-forth dynamics in the "direction" of evolution is exactly what we mean by "lack of directionality."

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.

Hi, ICdesign. When somebody proposes an alteration to a current mathematical conclusion, showing the alteration to be crap is sufficient to restore the current mathematical conclusion.This idiot assumes that all individuals with harmful mutations die without contributing to the gene pool.Then, he goes on to estimate that we still inherited 4 million harmful mutations from individuals who, according to his assumptions, shouldn't have contributed to our gene pool.Based on that, he worked out some more numbers that adjust the current human-ape split from 5 million years to 60 million years.Thus, when we rule out his obviously flawed math, we don't arrive at 60 million years: rather, we arrive at 5 million years, as before.But, this is off-topic here: personally, I think we could have continued it at the "problems with evolution" thread. Still, I think it's time for you to start a new thread if you want to discuss this any further.

---

-Bluejay (a.k.a. Mantis, Thylacosmilus)Darwin loves you.