Sep 092007

Once again, I’m helping to promote the lectures in our Philosophy Department’s “Think!” series. Our first event is approaching fast, so here’s the announcement:

The possibility of discovering life on other planets has fascinated and excited generations of people. Yet that scientific quest faces practical difficulties. In particular, if we do encounter alien forms of life, they may not be sufficiently similar to Earth’s living creatures to be easily recognizable as such. So what must we understand about the nature of life to know it when we see it?

  • What: Lecture on “The Search for Extraterrestrials: What is Life?” with Carol Cleland (CU Boulder)
  • When: Thursday, September 13th, 2007, from 8:00 to 9:30 p.m.
  • Where: Old Main Chapel, University of Colorado at Boulder

    Abstract: Many scientists and lay persons assume that the search for extraterrestrial life requires a definition of “life.” I argue that this is a mistake. What is needed to answer the scientific question “what is life?” is not a definition but a general theory of living systems, which we currently lack. In the absence of such a theory, we are in a position analogous to someone from the seventeenth century trying to define “water” before the advent of molecular theory. No analysis of the seventeenth century concept of water could have revealed that water is H20. Yet this is what is required to answer the question “what is water?” The upshot is that it is a mistake to design instrument packages for detecting extraterrestrial life around a specific definition of “life.” But this seems to result in a dilemma: If we don’t have a definition of “life” to guide the design of biological instrument packages, how will we recognize truly alien life if we find it? I discuss a strategy for circumventing this problem.

    Dr. Carol Cleland is a Professor of Philosophy at CU Boulder specializing in philosophy of science and astrobiology. She is also a member of the NASA Astrobiology Institute and CU’s Institute for Cognitive Science.

    All “Think!” events are free and intended for the public. Members of the media are welcome to attend. For more information, please visit

    For further information on the series, please contact Dr. Robert Pasnau at or (303) 492-4837. For announcements of upcoming “Think!” events, e-mail with that request.

    Upcoming “Think!” events:

  • Thursday, October 11th: Claudia Mills: “Honor Thy Mother and Father. But Why?” (8:00-9:30 pm, Old Main Chapel)
  • Thursday, November 8th: Simon Sparks: “What Counts As Art?” (8:00-9:30 pm, Old Main Chapel)

    These lectures are sponsored by the Center for Values and Social Policy in the Philosophy Department of the University of Colorado at Boulder. They are funded through the generosity of The Collins Foundation.

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