jiml@cavell.UUCP (Jim Laycock) (09/21/86)
In article <45500088@uiucdcs> tullis@uiucdcs.CS.UIUC.EDU writes: > So, I challenge anyone who reads this notesfile to the following >challenge. The challenge is: > > What is LIFE? > > Some things are definitely alive (I am, and you presumably are if >you are reading this). But how do we definitely draw the line between life >and non-life? What properties does a system have to have to be A LIVING >ORGANISM? LIFE is a vague term, as are so many words in our language. We have to approach defining the term from two angles: the intensional (as you suggested, listing the properties shared by LIVE things), and the extensional (listing those instances of things we would like to consider ALIVE that do not fall under our intensional definition). [Short digression: CHAIR is equally difficult to define. How can we explain to someone the concept that we use to denote office_chairs, wheelchairs, bean_bag chairs, park benches, electric chairs, and even tree stumps? If we provide a simple functional explanation {a chair is a man-made object that people sit on}, we leave open the possiblity that tables, or other objects upon which we can sit might also be chairs. The term CHAIR must intentionally be left vague to fall in line with our common-sense usage of the word. End digression.] Just as there are objects that are, without question, "chairs", there are systems that are unquestionably alive. The ~~FUZZY~~ edges of LIFE can be found at the birth and death of the definite cases: 1. Is a fetus alive? 2. Is a brain-dead person alive? and at the border-line between the definite and indefinite cases: 3. Is a virus alive? 4. Is a complex computer system alive? Our intuitions with respect to the above 4 questions should influence how we define LIFE in the general case. If you believe, as I do, that there is no single point at which something jumps from NON-LIFE to LIFE, or vice versa, then you hold that LIFE is a vague term, the ~~FUZZY~~ edges to which have NO CLEAR CHARACTERIZATION as to whether they are LIFE or NON-LIFE. Can something be ~~MORE ALIVE~~ than something else? Is there a continuum along which this relation can hold? When does a foothill become a mountain? -- Jim Laycock decvax!bellcore!ulysses!mhuxr!mhuxn!ihnp4!alberta!cavell!jiml OR alberta!Jim_Laycock@UQV-MTS Philosophy major, University of Alberta (5th year)
hurst@grc97.UUCP (Dave Hurst) (09/26/86)
> In article <45500088@uiucdcs> tullis@uiucdcs.CS.UIUC.EDU writes: > > So, I challenge anyone who reads this notesfile to the following > >challenge. The challenge is: > > > > What is LIFE? > > > > Some things are definitely alive (I am, and you presumably are if > >you are reading this). But how do we definitely draw the line between life > >and non-life? What properties does a system have to have to be A LIVING > >ORGANISM? > > LIFE is a vague term, as are so many words in our language. We have to > approach defining the term from two angles: the intensional (as you suggested, > listing the properties shared by LIVE things), and the extensional (listing > those instances of things we would like to consider ALIVE that do not fall > under our intensional definition). > > Jim Laycock I submit the following definition of life for your approval: Life is any system of processes which manifests self-organizing, self-reproducing, self-renewing patterns of behavior. I realize that this is a rather broad definition. It certainly encompasses anything that we might conventionally label as life. It also challenges our conventional perceptions of what life is. There could be many things which fall under this definition that we don't normally think of as being alive. I think that what this definition does do is give us some insight into what processes might have given rise to life-as-we-know-it, and what we should look for when dealing with life-not-as-we-know-it (e.g., self-reproducing computers, extraterrestrial life, or even Gaia). -- email: ...ihnp4!grc97!hurst David Hurst, KSC phone: (312) 640-2044 Gould Research Center flames: /dev/null #include <std.disclaimer> "Who are you?" "I am the new number two." "Who is number one?" "You are, number six." "I am not a number, I am a free man!" "Ahahahahahahahahaha!!