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Philosophers debate persistence conditions for personal identity because everything about us seems to change, including our cells, our memories, and our bodies. But DNA doesn't change and it codes for specfic traits in every cell of the human body. It's true that we experience changes in the way phenotypes are expressed in particular experiences or memories, but why not conclude that DNA is the ultimate source of personal identity? Philosophers don't seem to give this biological candidate serious consideration. Can you tell me why?

DNA does change. There are "point mutations", for example, in which say a single nucleotide changes, say from guanine to cytosine. . . . CTG TCA . . . becomes . . . CTG GCA . . . If there is a strand of DNA that suffers such a change, is it then not the same strand of DNA ? This is exactly like the question whether persons become different persons if they lose say half a finger. And now we have the problem of DNA identity. When are two descriptions sufficiently similar to count as descriptions of the same strand of DNA ? Anthony Quinton has the general issue right, in a 1962 article in the Journal of Philosophy called "The Soul": 'No general account of the identity of a kind of individual thing can be given which finds that identity in the presence of another individual thing within it. For the question immediately arises, how is the identity through time of the identifier to be established? It, like the thing it is...

My question is straight forward and people rarely have trouble answering. What is life or what makes life to be life? Is it simply just living or is there more to its definitin that we haven't explored. What is life?

There are several sense to the word "life", which derives from a Norse word having to do with the body; in German we have Leib , body. (1) There is a biological sense, which used to be taken to say that things possess life only if they possess respiration, excretion, reproduction, growth, irritability - I like this one - and cells. Locomotion is also characteristic of animal living things. Physiological life is life in this sense. (2) Life can also be taken to be consciousness or psychological life, so that only conscious beings have life; but I think that this should be taken to mean that only conscious beings have a life. Grass is alive, practically eternal, but it does not have a life, and we do not say that the different kinds of grasses lead separate lives because they don't lead lives at all. A derivative sense here is a life, meaning a biography, as in "A life of Churchill". A life in this sense is a book. (3) "Life" can also mean "way of life", so habits, customs and attitudes,...