Does partial scientific knowledge mean we shouldn't act?

Posted on 14 July 2010 by Stephan Lewandowsky

Guest post by Stephan Lewandowsky

If your Doctor presented you with the choice between laser surgery and likely blindness, would you have surgery to re-attach your retina? Probably yes.

Would you jump out of an airplane without a parachute? Hopefully not.

Those examples may sound trivial, but they are philosophically challenging and raise some deep questions about the nature of human knowledge.

Of course we all know that gravity exists. We know that if we jump without a parachute, gravity will swiftly and mercilessly determine our fate. Likewise, we know that laser surgery can prevent blindness, even if we don’t personally understand the details of how a laser actually does its magic.

But how complete is this knowledge? Does science know all there is to know about gravity? Does science fully understand the physics underlying lasers? No.

Science has a good understanding of gravity but it is only partial. In fact, there is much about gravity that eludes us! For example, our theories of gravity predict the existence of gravity waves, analogous to the electromagnetic waves that allow you to listen to the radio right now. However, despite hunting them for about a decade, we have yet to observe gravity waves.

We simply don’t know for sure how gravity works. Nonetheless we don’t jump out of airplanes.

Likewise, we don’t understand all aspects of the quantum mechanics that underlie laser technology. We nonetheless use lasers in daily life, ranging from laser pointers to laser surgery.

The message is clear: All scientific knowledge is partial.

But that doesn’t mean we are ignorant.

Far from it; our partial scientific knowledge is vastly preferable to ignorance because even with partial knowledge of retroviruses we can control AIDS, and with partial knowledge of nanotechnology we can develop cheaper solar cells to deliver more clean energy at an affordable price.

And for precisely the same reason, the fact that our knowledge of climate change is partial must not deter us from acting on that knowledge.

Although our knowledge of climate change may be partial, we can be certain that our climate is changing and that human CO2 emissions are responsible. The US National Academy of Sciences issued a clear statement just a month ago which reads: “Some scientific conclusions ... have been so thoroughly examined and tested, and supported by so many independent observations ... that their likelihood of ... being ... wrong is vanishingly small. Such conclusions ... are ... regarded as settled facts. This is the case for the conclusion that the Earth ... is warming and that much of this warming is very likely due to human activities.”

So anyone who says that we shouldn’t act on climate change because our knowledge is partial or uncertain isn’t saying that for scientific reasons. They either don’t understand how science works or they are being deliberately misleading.

Acknowledgements: I gratefully acknowledge the assistance of two of my colleagues in Physics, Dr. Thomas Stemler and Dr. Ralph James of the University of Western Australia, who suggested and then fact-checked the statements about partial knowledge of gravity and quantum mechanics.

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