What is Occam’s razor and does it really work?
Occam’s razor (also spelled Ockham’s razor) slices through complexity with a no-nonsense approach. The philosophical maxim “Numquam ponenda est pluralitas sine necessitate”, written by the 14th century Franciscan friar William of Ockham, translates as “Plurality should never be postulated without necessity”. In other words, all things being equal, simplicity is best.
So is this really true? Is the simplest explanation usually the best?
Not quite. Ockham never said that complexity is inherently inferior to simplicity, nor did he state that complex explanations are inherently wrong. Complex scientific questions often require complex answers, and that’s not at odds with Occam’s razor. The principle simply states that unnecessary complexity is, well, unnecessary.
“Occam’s razor is about finding the simplest solution that works”, johnjoe mcfadden (opens in a new tab)professor at the University of Surrey in the UK and author of the book “Life is simple: how Occam’s razor set science free and shaped the universe (opens in a new tab)” (Basic Books, 2021), he told Live Science in an email. “It never fails as long as you remember the necessity clause.”
ockham was not the first (opens in a new tab) promote simplicity. Aristotle maintained that “the most limited is always preferable, if it is adequate”, and Ptolemy considered it better “to explain the phenomena by means of the simplest possible hypothesis”. Some three centuries after the genesis of Occam’s razor, Isaac Newton would declare that “we must admit no more causes of natural things than those that are true and sufficient to explain their appearances.” Some 200 years after that, Albert Einstein would agree that “everything should be made as simple as possible, but not simpler” (which is, in fact, a simplification of his original quote (opens in a new tab)).
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When used correctly, Occam’s razor works. If two computer programs perform the same task, the one with less code is inevitably more efficient. The simplest medical diagnosis is usually correct; Hospital interns are often taught to think of horses, not zebras, when they hear hooves. An implication of the Second law of thermodynamics (disorder increases for any spontaneous process) is that such processes always use the least amount of energy possible.
“Copernicus came up with the heliocentric model of the solar system solely on the basis that it was simpler,” McFadden said. “The existence of a single Higgs boson was the simplest solution to the equations of particle physics. Between these points are a thousand scientific breakthroughs that depended on simplicity.”
However, when misused, Occam’s razor can become a blunt instrument of overgeneralization. The principle does not mean, for example, that we blindly follow the simplest theory, whether it is correct or incorrect. “Very often, the simplest hypothesis is too simple”, elliott sober (opens in a new tab)professor of philosophy at the University of Wisconsin-Madison and author of the book “Ockham’s razors: a user’s manual” (opens in a new tab) (Cambridge University Press, 2015), he told Live Science in an email. “The simplicity of a hypothesis It is one consideration, among others, that are relevant in assessing whether a hypothesis is true.
When it comes to data science, Occam’s razor can cause more problems than it solves. In this case, “the simplest approach is often wrong,” he said. Pedro Domingos (opens in a new tab), emeritus professor of computer science and engineering at the University of Washington in Seattle. When Domingos studied the applicability of Occam’s razor to machine learning in the early 2000s, he discovered that a simpler (opens in a new tab) model (opens in a new tab) it is superior to a complex one only if it is equally good at predicting new data.
“As modern machine learning has shown time and time again, in model ensembles, deep learning, etc., it’s usually the more complex approach that’s the right one,” Domingos told LiveScience in an email. “And that’s not surprising; The phenomena we are modeling are almost always more complex than the models, and the closer we get to their true complexity, the more accurate the models will be.”
Nonetheless, Occam’s razor remains a useful tool for trimming fat from bulky assumptions, at least in our everyday lives. “The universe is a complicated place, but sometimes it becomes more complicated through the invention of complicated explanations that suit a particular ideology, philosophy or political persuasion,” McFadden said. “Occam’s razor tells you to forget all that.”