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Ivory Tower: Psychological velocity

By January 18, 2019 March 13th, 2020 No Comments

In his book The Essential Tension, historian of science Thomas Kuhn recalls how he arrived at his famous idea that science progresses by abrupt revolutions rather than gradual improvement. He writes that he was reading Aristotle’s work on motion, and did not understand how Aristotle could have been so utterly wrong in his discussion of the concept. Aristotle believed that every object wants to move to its natural place. So, apples fall from trees because their natural place is down on the ground. This theory is pretty useless and devoid of explanatory power, according to Kuhn, especially when compared to modern physics.

But Aristotle was not a dumb guy. He invented logic, psychology, and biology. Muslim scholars, who protected science from Christianity during the middle ages, referred to him as ‘The First Teacher’. In the field of the philosophy of science, Aristotle is seen as the first person to articulate important parts of the scientific method – arguably, mankind’s greatest discovery. How could such a genius be so utterly wrong about something as elementary as motion?

Eventually, Kuhn realized that Aristotle’s concept of motion didn’t have the same meaning as ours. We conceive motion as the movement of an object in space. But Aristotle’s concept of motion was more similar to the abstract category of becoming: his theory of motion not only covered falling rocks, but also seeds becoming trees and children growing into adults. When Galileo redefined motion as the movement of an object in space, this was an act of genius, primarily because it changed the meanings of words in such a way that made Scientific Revolution possible: When you define motion in Galileo’s way, the definitions of velocity (change in position per time unit) and acceleration (change in velocity per time unit) follow smoothly, and classical physics is there for the taking. It’s interesting to think about the fact that this discovery of Galileo – perhaps the most important idea anyone ever had in
science – hardly involved any empirical observations. It was a purely theoretical move, a rearrangement of meanings.

Some wonder whether there will ever be a Newton of psychology – somebody who will articulate psychological laws and relate them in a mathematical system. I don’t think that will ever happen. Psychology does not have laws in the same sense as physics does, and I do not think that will change – in fact, I think that scientists who hope for psychological laws fail to appreciate the basic character of their subject matter. The fact that human behaviour is not governed by strict laws is exactly what requires explanation. Scientists should therefore try to understand why people have free will, rather than deny its existence.

However, it is interesting to wonder whether there will ever be a Galileo of psychology: A person who will change the meanings of psychological constructs in such a way that a new scientific paradigm appropriate for psychology will become accessible. But, on the other hand, you could argue that we have already passed this point. It’s certainly no less difficult for me to make sense of Aristotle’s psychology as it was for Kuhn to make sense of Aristotle’s discussion of motion (Google Aristotle’s wicked ideas on intelligence, memory, and personality, if you don’t believe me). So maybe psychology’s Galileo already surfaced many years ago, and we just didn’t notice.

In his book The Essential Tension, historian of science Thomas Kuhn recalls how he arrived at his famous idea that science progresses by abrupt revolutions rather than gradual improvement. He writes that he was reading Aristotle’s work on motion, and did not understand how Aristotle could have been so utterly wrong in his discussion of the concept. Aristotle believed that every object wants to move to its natural place. So, apples fall from trees because their natural place is down on the ground. This theory is pretty useless and devoid of explanatory power, according to Kuhn, especially when compared to modern physics.

But Aristotle was not a dumb guy. He invented logic, psychology, and biology. Muslim scholars, who protected science from Christianity during the middle ages, referred to him as ‘The First Teacher’. In the field of the philosophy of science, Aristotle is seen as the first person to articulate important parts of the scientific method – arguably, mankind’s greatest discovery. How could such a genius be so utterly wrong about something as elementary as motion?

Eventually, Kuhn realized that Aristotle’s concept of motion didn’t have the same meaning as ours. We conceive motion as the movement of an object in space. But Aristotle’s concept of motion was more similar to the abstract category of becoming: his theory of motion not only covered falling rocks, but also seeds becoming trees and children growing into adults. When Galileo redefined motion as the movement of an object in space, this was an act of genius, primarily because it changed the meanings of words in such a way that made Scientific Revolution possible: When you define motion in Galileo’s way, the definitions of velocity (change in position per time unit) and acceleration (change in velocity per time unit) follow smoothly, and classical physics is there for the taking. It’s interesting to think about the fact that this discovery of Galileo – perhaps the most important idea anyone ever had in
science – hardly involved any empirical observations. It was a purely theoretical move, a rearrangement of meanings.

Some wonder whether there will ever be a Newton of psychology – somebody who will articulate psychological laws and relate them in a mathematical system. I don’t think that will ever happen. Psychology does not have laws in the same sense as physics does, and I do not think that will change – in fact, I think that scientists who hope for psychological laws fail to appreciate the basic character of their subject matter. The fact that human behaviour is not governed by strict laws is exactly what requires explanation. Scientists should therefore try to understand why people have free will, rather than deny its existence.

However, it is interesting to wonder whether there will ever be a Galileo of psychology: A person who will change the meanings of psychological constructs in such a way that a new scientific paradigm appropriate for psychology will become accessible. But, on the other hand, you could argue that we have already passed this point. It’s certainly no less difficult for me to make sense of Aristotle’s psychology as it was for Kuhn to make sense of Aristotle’s discussion of motion (Google Aristotle’s wicked ideas on intelligence, memory, and personality, if you don’t believe me). So maybe psychology’s Galileo already surfaced many years ago, and we just didn’t notice.

Denny Borsboom

Author Denny Borsboom

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