Rebirth of Reason


Does New Knowledge Invalidate Old Knowledge?
by Joseph Rowlands

One of the more interesting epistemological arguments made by Objectivists is that new knowledge does not invalidate old knowledge. When you learn that a chair is made of individual atoms, it does not negate your previous knowledge about the chair. You would still understand that it is furniture, designed for people to sit it, etc.

In contrast, there is the commonly stated view that new knowledge as in science is constantly invalidating previous knowledge. You may have thought Newtonian physics was an accurate representation of the world, but Einstein's relativity invalidated all of that, or so it is said.

If this latter view was true, our whole world would constantly be shattered by each piece of new information. I think this view is fundamentally incorrect. We clearly don't start from scratch even when a major idea is accepted, such as the atomic theory or theory of relativity.

Unfortunately, those promoting the idea that old knowledge is not invalidated by new knowledge often overstate the case. They are left trying to support a theory of knowledge where it can never be invalidated by new information. The only way to do that is to keep knowledge extremely specific. If I see a piece of wood burn, I can say that I saw it burn, or that I've seen lots of cases where wood burns. But if I ever say all wood burns, I could find new information that invalidates it. The solution? While someone says that all wood burns, they are either being irrational or what they really mean is "to the best of my knowledge, all wood burns". Of course, then you aren't making a statement about the wood burning, but a statement about your present belief.

Some try to argue that all knowledge, if properly formed and formulated, is necessarily true and cannot be invalidated. I think this standard is flawed. I think it's perfectly fine to analyze the available information, draw a conclusion, and find out later that there were factors you weren't aware of. The quest for a method of induction that can never lead to incorrect results is unnecessary and futile.

More importantly, it is completely unnecessary in a discussion over whether new knowledge invalidates old knowledge. There's no problem with saying that sometimes it does, and sometimes it doesn't.

Consider an example of a child learning about battery types for his toys. He quickly learns that there are different types of batteries, like double-A, triple-A, C, D and 9-volts. He may be aware that there are others as well, but he ignores them since his toys don't need them. So he understands that there are different types, and he also understands that his toys will only work with one type. He has developed a causal principle.

A child may not understand that people designed the batteries to have different sizes. He may not understand even the basics of electricity. He hasn't derived this principle through deduction from more basic principles. But he does understand that only certain kinds of batteries work in his toys.

Now say he gets a new toy and it needs batteries. He goes opens up one of his toys he hasn't played with in awhile and takes out those batteries. They are the right size. So he concludes that he can use it for the new toy and it will operate. He plugs them in, and nothing happens. He asks his parents, and they tell him that the battery is dead. Batteries can only power toys for awhile before they stop working. These ones are out of charge.

Has this new knowledge invalidated his old knowledge? Yes and no. Clearly his conclusion that the batteries would work was faulty. To try to suggest that he had not made a mistake, even though he acted on it and failed, seems incredible. You can play with words and say that if he had phrased his conclusion in the right way, it would be technically correct. But he acted on his conclusion. He genuinely though it would work, and wasn't making a highly defensible statement about what he is justified in believing. He thought the battery would work, and it didn't. He clearly was mistaken.

And yet it's unfair to say that the new knowledge invalidated the old knowledge. He had a causal principle that he understood. The physical shape of the battery, which corresponds to the battery type, determines whether it will power his toys. This principle wasn't invalidated. Another principle was added. He now knows that batteries have limits on how long they will last.

The presence of this new principle doesn't invalidate the older one. Now that he knows both principles, he will have to make sure he uses the correct battery type and the battery needs to be charged. The initial causal relationship still holds. The shape/type is still necessary.

So some knowledge can be invalidate, while other knowledge is not. This makes sense. Learning more does not invalidate what you learned before. Discovering an additional causal relationship does not invalidate the former one. If the causal relationship was true, it remains true.

It also makes sense that some conclusions will be incorrect. We base conclusions on the available information. If there is important information that we aren't aware of, and no discrepancy pointing to missing information, there's no reason to doubt the conclusion. We can be justified in believing something is true, and yet find out later that it isn't.
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