What is the Meaning of Life?
Does life have a meaning?
Life, it might be argued, is the distinguishing feature of all organisms and may most usefully be thought of as involving various kinds of complex systems of organization providing individual organisms with the ability to make use of those energy sources available to them for both self maintenance and reproduction. Underlying this deceptively persuasive definition, however, lie those persistent traditional problems inherent in the search for an essential, distinctive substance characteristic of all forms of life. Additionally, as evolution theory makes clear, there is the problem of borderline instances, organisms of which it is not easy to say whether or not they may be defined as being alive. One such case is that of the virus.
Viruses are the smallest, simplest living things, smaller than bacteria, and the cause of some of the deadliest diseases known to humanity. They are composed chiefly of nucleic acid wrapped in a coat of protein and are able to multiply only from within living cells. As with all other organisms, the virus depends for its ability to obtain energy and carry out the other processes necessary to sustain life, upon its stock of DNA, the hereditary material that makes up the genes, the "instructions" that determine the traits of every living organism. What is interesting about viruses, however, is that their genetic stock is very meagre indeed, so much so that reliance upon it alone cannot enable them to survive. Nonetheless, viruses do persist from one generation to the next, as if they were alive. How this is managed, as it clearly is in both plants, animals and human beings, bears importantly upon the ways in which "life", at least in the case of viruses, may legitimately be defined.
Advances in molecular genetics and the consequent growth in understanding of the developmental processes of organisms have tended to lead to the consensus, among both scientists and philosophers, that no explanatory principles important to the life sciences are likely to be found anywhere but within those sciences themselves. Vitalist notions that there is some feature of living organisms that prevents their natures being entirely explained in physical or chemical terms only have, as a consequence, been increasingly eclipsed.
In vitalist doctrine, this mysterious additional feature may be argued to be the presence of a further entity, such as a soul, although it may also be explained as having to do...