Induction and Yellow Scientific Journalism

TL;DR – Scientific investigation is not simply finding patterns and generalizing from them.

Sometime ago I met someone who had high standards for what truth is. “Science cannot give any real truth!” “Science uses induction, which is not logically sound.” “All that scientists do is find patterns and generalize them to a rule.” I guess induction is in the eye of the generalizer.

When discussing scientific methodology, induction is often mentioned. Roughly speaking, deduction is when one argues from general to particular. For example: “all men are mortals”; “Socrates is a man” therefore “Socrates is mortal”. Induction is when one argues from particular to general. For example “Socrates is a man”, “Socrates is mortal” therefore “all mortal men are named Socrates”.

Naturally, there is nothing that guarantees that you are making the correct generalization or that the generalization will always hold. And some people argue that this limits the soundness of scientific results. For example: a scientist drops a few lead balls; they always fall to the ground; he makes a rule that lead balls fall to the ground. But there is nothing that in principle guarantees us that tomorrow lead balls will not do something different: like spontaneously transform into chickens. That would be delicious.

But is this how actual science works? Are scientists really sitting around all day looking at things and making gross generalizations? Or they do something completely different? Let’s explore this question with another inductively deductible thought experiment.

Yellow scientific journalism

You are a journalist. You spend your time searching for news and then rush out to be the first to publish the scoop. Some people may urge you to spend more time “checking your facts” or contest that random people on twitter do not “constitute a reliable source”. Some people call you a yellow journalist, but that does not bother you. The sun is yellow. Gold is yellow. You consider yourself a golden journalist.

You decide to cover scientific topics. Gravity is a topic that carries some weight, so you decide to investigate. You randomly drop some items off your table, and you notice this interesting phenomenon. If you take two sheets of paper, crumple one, and let them fall at the same time, the crumpled one will reach the ground before the other. So you publish your first scoop: “Spherical objects fall faster than flat objects!”

The response from the “scientific establishment” (i.e. anybody with a basic understanding of physics) to your article is negative. Some suggest to compare the fall of one sheet of paper with a book. You do this, and note that the book reaches the ground before the single sheet of paper. So you write your second scoop: “Heavier objects fall to the ground faster than lighter objects”.

Again the reaction from the establishment is negative. Some say that your articles are gross generalizations and are not well-researched. They say you didn’t take friction into account and that you should try making things fall in a vacuum. You open up your vacuum, but you fail to see how dropping things in it would make any difference.

Yet, the twitter user GalGal presents an interesting argument. Suppose that you have two objects of different weight. Suppose the heavier falls faster than the lighter. Now suppose you tied them with a string. Would the lighter drag the heavier, making it fall slower? Or would they count as a single object of heavier mass, making it go even faster? How thick has to be the string between the two objects so that they become one object of heavier mass? The idea of heavier objects falling faster, then, presents paradoxes. If every object, ignoring friction, falls at the same rate then one does not have these paradoxes.

All this thinking made your head hurt, so you decide to move onto other branches of science. You publish articles such as: “all regulations are bad for the economy” “there are no biological differences between men and women” and so on. While you still get negative reaction from the scientific establishment, your articles are retweet and shared a lot, providing the readership and ad-revenue that you craved so much.

Ruling rules out

When Galileo Galilei dropped the spheres of different weights from the tower of Pisa, he was not really testing a hypothesis. He already knew the answer. They had to fall at the same rate because the opposite premise would lead to contradictions. He didn’t drop things at random and find a pattern. He arrived at the conclusion logically and devised an experiment that clearly conveyed it.

The point is that there is no prescribed recipe for how you get to the correct scientific answer. Indeed, often you simply have some interesting system to play with, you get familiar with it by doing different things, and you start characterizing it intuitively by creating some heuristic. That is, some rule of the thumb. Like “when you drop bottles of beers to the ground, the people you took them from become unhappy.”

But this is not at all exclusive to science. It happens in math as well: you may have a new mathematical construct, you play around with it and you start characterizing it intuitively by forming some conjectures. You see: it’s not that Pythagoras started proving theorems at random until he proved that the square of the hypotenuse is equal to the sum of the square of the sides. Egyptians and Babylonians already were familiar with Pythagorean triples, so they knew the theorem as a heuristic. Pythagoras showed that it could not be any other way, that it wasn’t a mere coincidence. Even in math, the proof typically comes after the heuristic: you can’t write a proof for a theorem you haven’t even stated. And if what you stated seems unreasonable, you are not going to try to find a proof for it.

The same goes in science: you look for pattern and form heuristics. But those are not laws: for that you have to show that nothing can violate the rule. That is: it’s not enough to see that energy is conserved in a few cases and generalize. You have to try all possible ways you can think of to create the opposite result. You can’t simply repeat the same thing over and over. Once you have exhausted all ideas, and everybody else has done as well, and shown that the idea is logically sound, and so on and so forth, then you can say: “energy conservation agrees with experimental evidence”. This is not at all induction.

This also means that not all topics can be studied scientifically equally well. It is somewhat difficult to show conclusively the impact of a particular diet on childhood development as parents do not appreciate when you take away their children and put them in a tightly controlled environment. Therefore disciplines like physics or chemistry are always going to have an easier time providing solid conclusions than macroeconomics or cosmology.

Induction does not play a fundamental role in science. You can use it as a stepping stone in the process. But there is no general prescriptive recipe to reach the correct laws. You use whatever works. Just like in real life.