For Those Who Want to Ring in the Fourth Millennium

The quest for immortality has been in the news of late. Silicon Valley is out disrupt the most ancient of human pursuits: the defeat of aging and death. At the same time, new research raises the question: Is it wise to try to live forever?

Source: Rodrigo Ramirez/Flickr

The desirability of extending your lifespan now depends on your identifying with the person who will answer when your name is called in a few centuries. It just doesn’t make sense to hope that you live for a thousand years if the person who will be alive at the dawn of the fourth millennium is not you. But we all know that our personalities change over time, and the longest longitudinal personality study to date suggests that the longer you are alive the more your personality changes. It seems as if the person who will benefit from the anti-aging research by Calico, a Google offshoot, will not be Larry Page.

But do these changes in personality really signal a change in personal identity? It’s not so clear that they do.

First of all, there is research that suggests that when it comes to personal identity, the most important psychological factor is continuity of moral traits across time. Suppose you meet someone you knew in college after having not seen her in 40 years. You will be unlikely to consider her the same person now as she was then if, for example, she went from being kind to being cruel, or from being accepting to being racist. But you will be more likely to consider her the same person now as then if she went from being ambitious to lacking ambition, or from being incurious to curious. Thus, it’s not so clear that the personality traits reported on in the recently completed longitudinal study (e.g., desire to excel and originality) are really central to our conception of personal identity. This other research suggests that changes in these personality traits are consistent with personal identity over time, whereas changes in moral traits are not. So long as Larry Page now has good reason to suspect he will share a moral compass with Larry Page in the year 3001, he has good reason to think he will be the same person then as he is now. And so it may make sense for him to seek to extend his lifespan for a thousand years.

A second reason to think that your personal identity can persist across several centuries has to do with the nature of the changes it will undergo. Not all personality changes are made equal. Sometimes people’s personalities change due to a disease, such as Alzheimer’s, or an accident, as in the case of Phineas Gage. And sometimes they are due to an active effort on the part of the person, such as when you work to cultivate an increase in self-confidence or ambition. So long as a change in your personality is due to your assessment that there is good reason to make it happen, there seems little reason to insist that this would change your fundamental identity. After all, it was you who decided to actively shape a feature of yourself. Why think of this as an act of self-effacement, as opposed to an act of self-discovery or reinvention?

Moreover, even if your personality were to change due to a disease, such as Alzheimer’s, further research by the team cited above suggests that it is still the moral traits that matter most. Once again, there does not seem to be good reason to think that the fact of personality change over time shows that one’s personal identity cannot span the centuries.

To be sure, there are serious (even if not decisive) worries about radical life extension—overpopulation, exacerbated inequality and resource scarcity, to name a few. But personality change may not be one of them.