We still have a long way to go when it comes to designing good theories, at least in psychological science. On the topic of 'we have a long way to go', psychology is often juxtaposed with physics, where one might get the impression that physics is doing better than psychology, as a science, on all counts. Embarrassingly for psychologists, Popper famously compared Einstein's and Freud's theories, with Einstein's theory of relativity being an example of good science, as it made a verifiable prediction that hadn't been, but could be empirically tested. Freud's theories, on the other hand, were unfalsifiable, as any observed phenomenon could be explained post-hoc.
There are already many blog posts that discuss how we should be, or why we shouldn't be, more like physicists. Of course, physicists have advantages that we don't have, such as precise measurements and centuries of numerical models to build on. Aspiring to improve is always a good thing, but maybe we can also look at the flip side of the coin: To not only compare ourselves to a gold standard and potentially discover that we just can't, but also to see where others went wrong to avoid repeating mistakes.
With these thoughts in mind (or something along these lines), I started digging a bit into theories that didn't work out. So far, I haven't found that much, so I welcome any recommendations for reading on this topic!
The first unsuccessful theory that I started googling was alchemy. It's often described as what came before chemistry, except the people back then didn't really know what matter was made of, so they did meticulous work and maybe even discovered some principles that are still relevant for modern chemistry, but mainly went on wild goose chases to achieve immortality or to turn base metals into gold. I came across a historical character who sounds pretty cool: Cleopatra the Alchemist (https://en.wikipedia.org/wiki/Cleopatra_the_Alchemist), not to be confused with the empress, who lived in the same country of Egypt but in a different century. Alas, it seems that back in the days, reproducible working was not a thing yet. Apparently, the writings of alchemists are difficult to decipher, because they often wrote in code (https://www.youtube.com/watch?v=gxiLuz9kHi0).
What can we learn from that? First, that we should work reproducibly, even when it comes to documenting our ideas and trains of thought. Second, there may be a broader message there, something about not letting our own personal interests dominating our research. Achieving eternal life or unlimited wealth may be an ultimate aim for some people in life, but perhaps it's important to concentrate on the little steps and the scientific achievements that we make on the way there.
The second unsuccessful theory that came to my mind is Lamarckian evolution. This is a theory that, in my undergraduate course of biology, was juxtaposed to Darwin's theory of evolution by natural selection. Lamarck built on the obvious observation that children are similar to their parents, and suggested that parents can pass on acquired traits. The example from the textbook was the giraffe's neck: A giraffe stretches its neck to get to the leaves on the top of the tree, and because this makes its neck longer, its children also have longer necks. The example on Wikipedia is a blacksmith, who acquires muscles through his work, and then his children become physically stronger, too.
Interestingly, the Wikipedia page on Lamarckism (https://en.wikipedia.org/wiki/Lamarckism) has a whole section on "Textbook Lamarckism", criticising exactly what I described above: Naming Lamarckian and Darwinian evolution as two sides of the same coin, one being bad and the other one being good. Apparently, Darwin believed in the passing on of acquired traits, just as Lamarck did. What we learned in biology class was that Darwin's theory of evolution by natural selection stood the test of time because later research, namely the advent of genetics, showed support for a mechanism that could account for transmission across generations and didn't involve the passing on of inherited traits. I think the lesson that we were supposed to learn from this juxtaposition was how important the specification of mechanisms is: undoubtedly, this is an important lesson for psychological scientists. What I personally found cool about Darwin's evolution by natural selection was its reliance on deductive reasoning: If there is variability between individuals of the same species, and this variability allows some individuals to survive with a higher probability than others, and the individual differences are passed on across generations, then those with the more successful variant will survive, leading to survival of the fittest and evolution by natural selection. For psychologists, achieving theorising based on deductive reasoning may be as utopian as achieving the measurement accuracy of physicists, who apparently throw out a tool if its test-retest reliability is less than 0.99. But it's nice to dream.
Speaking of physicists, the third theory is Cold Fusion. I learned about it only when I met my husband, who is a physicist working with hot fusion. With hot fusion, a nuclear reaction happens when matter is heated up to hundreds of millions of degrees. Cold fusion was supposed to work at room temperature. The first mess underlying this theory was on the empirical level: after the initial study demonstrating fusion at room temperature was published, other labs failed to replicate it. The original study was apparently difficult to replicate in the first place because the experiment was not well-described, and when participants did, they were not able to find the excess heat that was supposed to be a product of the reaction. There is even talk about fraud in the original experiment. So, cold fusion went quickly out of fashion, and is not taken seriously by the overwhelming majority of physicists.
The celebratory conclusion of this whole fiasco is that replication studies can identify false positives: empirical phenomena that are just not there. The focus of this blogpost, however, is on theories, not on empirical replicability. So, what can we learn from cold fusion about theory building? Well, apparently there wasn't that much theory behind it in the first place. So yes, the implication is: Even physics has a story about how researchers published a sexy, unbelievable finding based on a wishy-washy theory, and led a whole research community down a rabbit hole trying to reproduce their results -- including a relatively recent replication failure published in Nature: https://www.nature.com/articles/s41586-019-1256-6.
What is the overall conclusion? Admittedly, I don't think we learn much from these three case studies that we didn't already know. It might be important insights, but those that are already part of the mainstream discussions -- otherwise, I probably wouldn't know about them in the first place. In theory building, as with most other complex things, it's easier to do things wrong than to do things right. This is because, for a theory building process to be right, all of the underlying processes have to be right. If one step is wrong, the theory is wrong. And there are many more ways to do things wrong than to do things right. Probabilistically, the odds are against us.
And yet it's probably worth considering exactly what has gone wrong when we have come up with wrong theories in the past. By eliminating possible mistakes, we can increase the ratio of right-to-wrong theory building processes. So, I'm looking forward to extending my collection on wrong theories! Please feel free to post any leads in the comments!
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