As you know, I love science. I’m a little obsessed. But there are people who get annoyed or even offended by my obsession with science, and every once in a while one of these people will remind me, sternly, that science can’t explain everything. And you know what? I generally agree with that sentiment. But then people start declaring that science will never know this specific thing or that specific thing, and I immediately think of a certain 19th Century French philosopher named Auguste Comte.
Comte was not some scientifically illiterate buffoon. He wasn’t one of those 19th Century evolution deniers, or one of those latter-day opponents to the heliocentric model of the Solar System. In fact, Comte is regarded today as the very first philosopher of science, in the modern sense of that term, and he gets credit for coining the word “sociology” and for laying the philosophical foundation for that entire branch of science. There’s also a wonderful quote from Comte about the mutual dependence of scientific theory and scientific observation. Basically, you can’t formulate a theory without observation, but you also can’t make an observation without the guidance of a theory.
But that is not the Comte quote I think of whenever somebody starts lecturing me about the things science will never know. It’s this quote about the stars: “[…] we shall never be able by any means to study their chemical composition or their mineralogical structure…” Comte also declared that: “I regard any notion concerning the true mean temperature of the various stars as forever denied to us.”
Comte wrote this in 1835, and if you can put yourself into an 1835 mindset you can see where he was coming from. There’s no such thing as rocketry. We don’t even have airplanes yet. And even if you could fly up to a star (or the Sun), how would you measure its temperature? What kind of thermometer would you use? And how would you go about collecting stellar material, in order to determine the star’s chemical composition?
According to Comte—a highly intelligent and very pro-science person—this sort of knowledge was utterly impossible to obtain. And yet only a few decades later, thanks to the invention of the spectroscope, scientists started obtaining some of this unobtainable knowledge. For those of you who don’t know, spectroscopes separate light into a spectrum. Some parts of the spectrum may appear brighter or darker than you might otherwise expect, depending on which chemical substances emitted or absorbed the light before it reached the spectroscope. And so by comparing the spectral lines of chemicals we have here on Earth to the spectrum obtained from the light of a star, you can determine the chemical composition of that star.
You can also measure a star’s temperature thanks to a concept known as black body radiation. Basically, black body radiation refers to the fact that things glow as they got hotter. If no other light sources are involved, then the color of a glowing object will be directly related to that object’s temperature. Ergo, if you know what color a star is, then you can work out a pretty accurate estimate of what temperature that star must be.
Auguste Comte didn’t foresee any of this. It is certainly true that science does not know everything, and there are surely things that science will never know. But if you think you know, specifically, what science can never know, I question that. Someday, some new invention (like the spectroscope) or some breakthrough discovery (like black body radiation) may turn an utterly unknowable thing into a matter of trivial measurements and calculations.
Maybe the one thing science truly can never know is what science’s own limitations are.
WANT TO LEARN MORE?
Here’s a very brief post about Auguste Comte, what he said about stars, and how epically wrong he was with that one prediction.
Also, here’s a short article about some genuine limitations that science has, like aesthetics, moral judgements, etc.