Hilary Putnam once asked a funny question: If all of the things we have heretofore called cats turned out to be robots from Mars, would we have discovered that all cats are robots or, rather, that there are no cats? Putnam went with cats are robots, and on the basis of this intuition he argued that the extension of a term- the set of objects to which it refers- is not determined by our concept of it, but rather by its paradigm cases.
This view is now known as semantic externalism, and I'm largely down with it. Though I actually think it's a mistake to discuss things like this as if we were discovering the real meaning of meaning. The truth about meanings is that they are conventional and we can change them anytime we agree to. If scientists decided in such a case that there were no cats, and invented a new term to refer to these robot thingies instead, no grievous error would have occurred that philosophers would be required to go back and set straight. I see Putnam not so much as having discovered part of the real meaning of meaning, but rather as having made a strong, useful proposal for rationalizing some of the conventions by which we allow meanings to change.
Putnam's robot cat example can seem pretty out there to someone not acquainted with the crazy thought experiments philosophers use in an effort to clean up our conceptual framework. But the history of science and philosophy is replete with similar episodes in which we need to determine whether some phenomenon doesn't exist, or, rather, is just very different than we had supposed, i.e., veditwhasup.*
Here is a slightly different take on robot cats- which I believe is compatible with Putnam's views- in terms of the concept of explanation. What I'll suggest is that whether we decide that a phenomenon doesn't exist or is just veditwhasup depends a great deal on the explanatory context.
Start with witches. Although a large chunk of humanity still believes in witches, in a scientifically enlightened community it is uncontroversial to say that there are none. How did we get from a position of near universal belief in witches, to the view that witches don't exist? I say the reason we say there are no witches is that the phenomena to be explained have disappeared. There was a time when we were in dire need of an explanation of how people get turned into newts. The widely accepted explanation is that it was due to witchcraft. Since then, we have come to doubt that humans do get turned into newts. Hence, we are no longer in need of witches to explain this.
Last year I discussed a few important scientific episodes in which the phenomenon to be explained was determined to be an illusion. Some of these cases we may understand in a manner that is analogous to the above. For example, we do not say that planetary epicycles are veditwhasup. We say that they don't occur, because retrograde, the phenomenon they were invoked to explain, is an illusion. We do not say that the designer of plants and animals is just veditwhasup, because we have come to realize that design itself is an illusion. For the same reason we no longer require the gods as an explanation of fate. If you ask why some things are fated to happen, regardless of what we do to prevent them, you are laboring under an illusion.
However, this particular explanatory model does not fit all the cases, even in the realm of superstition. For example, epilepsy was once widely explained by reference to demonic possession. But we did not reject possession on the grounds that epileptic fits are illusions. Similarly, in science we did not reject the existence of caloric and phlogiston because heating, cooling and combustion do not occur. We no longer believe in humors nor miasmas, but that is not because there is no such thing as the diseases they explained. We reject the élan vital and the soul, but that is not because we no longer believe in the unity of consciousness or the self-organizing properties of living systems.
In these, and many other cases, the reason we have stopped believing in these entities is that we have hit upon radically different and better explanation of the phenomenon in question. When this occurs, it often makes sense to reject the existence of the entities we are appealing to in explaining the phenomenon, but not the ones we are trying to explain.
What's interesting is that this is very often exactly what people do recommend.
For example, philosophers and scientists often claim that if determinism is true there is no such thing as free will. But if free will is just the remarkable human ability for deliberative choice, of course it exists. All we have rejected is a ghost in the machine explanation of it. A similar point holds for the concept of knowledge. People often conclude that there is no such thing as knowledge when they learn that certainty is unachievable or that the notion of our ideas resembling an external reality makes no sense. But all this means is that we had a false explanation of how knowledge works. Veditwhasup. Again, people often claim that there is no such thing as human altruism when they learn that people get pleasure from helping others. But this is foolish. Human cooperation and self-sacrifice happens. We just had a very wrong idea of how.
In sum, there are two good reasons for thinking that some theoretical entity or process we previously accepted does not exist. The first is that it explains as real what we have come to regard as an illusion. The second is that we have developed better and fundamentally different explanations of the reality in question. Failing either of these, I would suggest raising the following question. Could it just be veditwhasup?
Department of Philosophy
Sacramento State University
*Either of Old Saxon origin or coined by me just now as an acronym for the purpose of staying under the 1,000 word limit imposed by this blog.