Map of life expectancy at birth from Global Education Project.

Tuesday, May 11, 2021

Epistemology III: The Scientific Method

Okay, here's the dirty secret: there is no such thing. Scientists use many different methods. Some methods are characteristic of certain disciplines, while within disciplines there may be groups of scientists who specialize in or emphasize various methods. This is territory I fear to tread because it can give people some wrong ideas, also because it's quite complicated, but I'll try to keep it simple and be careful about walling off the wrong ideas.

In fact philosophers have found it very difficult to define science, or to clearly distinguish it from non-science or pseudo-science. Despite the pretensions of some, science is a flawed human enterprise and can be affected by cognitive biases, mistakes, and fraud. It is also dynamic -- we can't say that past theories that are no longer considered valid were unscientific. They may have been created by people who were doing perfectly good science at the time. That scientific theories and conclusions are often superseded -- that they turn out to be wrong -- leads some people to decide that there is no reason to believe anything scientists say, and that homeopathy or creationism are just as legitimate. In the jargon, they grant no "privilege" to science over other forms of explanation or knowledge generation.

Karl Popper, an Austrian-British philosopher, is well known for maintaining that the main criterion for a proposition being scientific is that it be falsifiable. It has to make predictions which, in principle at least, can be shown to be wrong. He should have added, in most people's view, that its proponents have to accept that it is wrong once the falsifying evidence shows up. However, even with this codicil, the idea is too slippery to really work. For one thing, you can usually find ways to modify the theory -- add a new piece that explains the discrepancy. That's how the ancient Greeks came to keep adding epicycles to account for planetary motions that didn't work in their simpler geocentric universe.

What killed the Ptolemaic universe was that Copernicus found a much simpler explanation. Galileo's observations of the phases of Venus certainly made the Ptolemaic universe require even more complicated bells and whistles, and the heliocentric universe worked much better -- until it didn't. Now we have a universe that has no center -- except that the center of the visible universe, all of the universe that we can ever see or know, is once again the earth, although at the same time the earth has no special importance, except to us. Everywhere else is also at the center, from its own perspective. Is this idea simpler? I'm not sure. It doesn't require all those epicycles but it requires a lot of differential equations and in fact the gravitational interactions of multiple bodies are unsolvable. 


The theory of evolution is in fact a whole lot more complicated than creationism, and it keeps getting more complicated. Parts of it that were once essential dogma have been abandoned, replaced by different concepts. Darwin had remarkable insights, but his theory is no longer the accepted theory. I suppose you could say that it has evolved. You could also say that it has been falsified, except that it hasn't -- essential pieces remain, so we still call it by the same name.

So maybe Popper should have said falsifiable or correctable, the distinction being a matter of degree. We should presume that whatever theories we hold today may be corrected in the future. Since Einsteinian gravity replaced Newtonian gravity, was Newton wrong? Not really. His theory worked just fine for the conditions he was able to observe and within the accuracy of the measurements he could make. But Einstein's theory is both more accurate and of wider application. It explains the motions of solar system bodies more accurately (although only within measurement tolerances unavailable to Newton) and it explains the much larger scale and much higher velocities of motion in the larger universe much better. Nevertheless many physicists are starting to think there may be something wrong with it. For one thing, they've had to add the epicycle of dark matter, a completely unexplained phenomenon which would account for 85% of all the matter in the universe. Oops! They've also had to add dark energy (aka the cosmological constant), another completely unexplained epicycle that accounts for 69% of all the mass-energy in the universe. Double oops! Finally, the theory cannot be reconciled with the current theory of the other forces in the universe, electromagnetism the strong forcee, and the so-called weak force. (Oh yeah, maybe there's a fifth one lurking.)

But where the average person has the most trouble is with biomedicine and its black-sheep cousin, epidemiology. To be continued .  . .


Chucky Peirce said...

My simplified description of science is that it is not so much a tool for finding truth as it is one for eliminating false or useless ideas. The principle, to channel Sherlock Holmes, is that once you've eliminated everything that can't be true, you'll be left with the truth. Of course we now realize that it just lets us navigate farther into the jungle.

This causes confusion when talking with fundamentalists. They feel like they have a route to the absolute Truth, but 'Science' isn't really built to do that. Its better at clearing out the weeds. And The Truth is, sadly, vulnerable to it's scythe.

Don Quixote said...

“Cherish those who seek the truth but beware of those who find it.” —Voltaire