What makes a ball roll?

“What kind of question is that?” you might ask. Isn’t that self-evident? Pushing it or kicking it is the obvious answer. And what makes a ball bounce? Dropping it to the floor or kicking it through the air, obviously. What makes a ball do other strange things, such as deflating? Pricking a ball with a needle would do the trick. But what could possibly make a ball sing? I will return to this question later – although the obvious answer is that balls don’t sing.

I much appreciate David Harriman’s book The Logical Leap, and I appreciate Leonard Peikoff’s lecture series on which the book is based.[1] I know too little about physics or about the history of science to be able to judge the objections that have been raised by John McCaskey; but I do know what makes balls roll and what makes paper burn and many other examples of “first-level generalizations”. I write this mainly to test my own understanding.

Harriman writes:

A toddler, say, pushes a ball and it rolls away. How do we formulate (in adult, conceptual terms) what the child actually perceives here without benefit of language? Here are three formulations: “I rolled the ball by pushing it”; “My pushing it made the ball roll”; “I caused the ball to roll by pushing it”. (The Logical Leap, p. 22.)

Let me take this one step further. The toddler may go to the beach and observe that the ball rolls slower on sand; and he may take the ball into the water and observe that it does not roll at all on water; he has to push it constantly to make it move at all. Does this invalidate his initial generalization? Certainly not! What he has to do with his first “first-level generalization” is merely to modify it in view of the wider context. This is how knowledge grows.

Harriman himself has another example to demonstrate the same point:

A child learns, for example, that pushing a ball makes it roll. Later he discovers that this does not happen if the ball reaches a certain weight, or if it is glued to the floor, or if it is made of iron and sitting on top of a strong magnet. None of this overthrows the initial first-level generalization. On the contrary, the latter is necessary for anyone to consider subsequent qualifications. One cannot reach or validate “Pushing moves a ball only under X conditions” until one has first grasped the elementary fact that “pushing moves a ball”. (P. 20.)

One can take other examples to illustrate the same point. (Of course, they are all very “childish”.) Take the example that fire makes paper burn. The toddler may observe this only to later observe that if one puts a soaking wet newspaper into the fire, it does not catch fire or at least takes longer to catch fire. This does not invalidate the toddler’s knowledge; it expands it; he knows it does not apply the same way to wet paper as it does to dry paper. (The same would go for wood: the dryer the wood, the more easily it catches fire.)

Or take the first-level generalization that water extinguishes fire. It does not take too long to realize that the amount of water and the size of the fire are important factors here. A small fire may be extinguished by a glass of water, but a big fire would not.

Some mistakes may be possible even on this very elementary level. Say the toddler mistakenly makes the generalization that liquid (any liquid) extinguishes fire. He is in for a very unpleasant surprise, if he tries to extinguish a fire with petrol. (Admittedly, this is a rather contrived example.)

But back to the question of singing balls. Balls don’t sing. So what could possibly make it sing? Well, this is what Travis Norsen writes in his Amazon review of Harriman’s book:

But take another example: say, a ball (containing batteries and appropriate electronic circuitry) that, when squeezed, plays a little song. Now, there is some sense in which a child who squeezes this ball and hears the song is perceiving causation: he is perceiving an entity acting in accordance with its identity, and that, according to Objectivism, is what causality is. But here, it seems to me that — unlike the case of the rolling ball — the specific features of its identity which underwrite the action in question are not relevantly available in perception. So presumably it would be wrong for a child to generalize, in this case, to “balls sing when you squeeze them” or just “balls sing” for short.

Is this a valid counter-argument? I don’t think so. It is even more contrived than the petrol example I gave above. Why on earth would anyone construct such a ball (or such an argument, for that matter)? In order to fool little kids into making the false generalization that “balls sing when squeezed”? Well, even if one were to succeed in fooling some kid this way, the kid would soon correct his mistake: he would encounter several balls that don’t sing at all when squeezed, and he would realize this was a very exceptional experience.

I asked Harriman on his blog what he thinks about this counter-example, and he answered:

What would a toddler’s response be to a ball that sings when he squeezes it? The child would laugh with surprise, because he knows that squeezing doesn’t cause singing. Anyone who can’t see the difference between the pushing/rolling example and the squeezing/singing example has spent too much time with professors and not enough time with children.

I agree.

And for another example of what kinds of misunderstanding surround this book, see A Weird Confusion about Concept Formation.


[1]) I have some serious disagreements with Leonard Peikoff, above all his unjust treatment of me. But I have to admit he has done a good job on the issue of induction.

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