According to Millikan’s naturalistic explanation of what gives something function, anything with a function must have a past of its own or a series of ancestors from which it has been copied. If something doesn’t have a certain type of past, in which it inherits the functions of the ancestors from which it was copied, then it cannot have any function of its own. A simple objection to this claim involves something without a past of its own or a series of ancestors from which it received its function(s), yet which nonetheless seems to have a function. Modern screwdrivers have the function of driving screws for the simple reason that each screwdriver is a copy of previous screwdrivers, which also had as their function driving screws. However, the very first screwdriver was not copied from any earlier version that had the same or even a similar function. If we can find no explanation for how the first “ancestor” of a thing got its function, then we will be hard pressed to justify Millikan’s claim that a thing has as its function whatever its ancestors had as their function.

Another objection to this claim involves some kind of spontaneously-formed “swamp creature” that is identical in every way to a particular human being, say, for instance, President Bush. Presumably, this creature would do exactly what Bush would do if he were in the same situation. If Swamp Bush were to encounter a bag of pretzels, then presumably he would at least appear to eat the pretzels with as much enthusiasm as Real Bush would eat them. If Swampy then appeared to choke on a pretzel, we would probably say that something was “wrong,” or that some process (i.e. chewing and swallowing food) had “malfunctioned.” If Real Bush choked on a pretzel, we would be correct to say something wrong happened, because his biological history makes it the function of his mouth and throat to transform solid food into a saliva-laden mushy substance and then to send that substance down his esophagus and into his stomach. This is the action of his ancestors’ mouths and throats that allowed for more mouths and throats to come into existence in future human beings. Swampy, on the other hand, has no such biological history, so it would be incorrect of us to assume that the function of his mouth and throat is the same as the function of Real Bush’s mouth and throat. In fact, we would be incorrect to assume that Swampy’s mouth and throat had any function or purpose at all.

Most of us probably have a very strong intuition that the first screwdriver had a function to drive screws, as well as an intuition that the purpose of Swampy’s mouth and throat is the same as the purpose of Real Bush’s mouth and throat. (While there are many philosophers who put all to much faith in human intuitions, if we don’t at least take note of what these intuitions are, we run the risk of coming up with a theory that redefines concepts to the point where the theory is about something else entirely.) However, we may be able to explain both these intuitions with a naturalistic theory once we understand the limits of what a naturalistic theory must accomplish. A naturalistic theory need not explain all instances of function and purpose in terms of natural processes. All the theory really needs to do is explain the most basic instances of function and purpose in terms of natural processes. It is then our job to find an explanation for more complex functions, many of which might be impossible to explain in a basic naturalistic way, that relies on these more basic instances of function and purpose.

The function of the first screwdriver can be explained in terms of the desires of the person who invented it. That person’s desire to create a screwdriver was a specific manifestation of the more general human desire to alter physical objects in such a way as to make other actions require less energy to complete. This general desire has the kind of past that Millikan requires for something to have function, as human beings throughout our history have desired to invent things to make their lives easier. The screwdriver, then, has the function to drive screws because it was created from a desire that had as its function the creation of a device to drive screws. The function of Swampy’s mouth and throat is harder to explain in this way. Perhaps this particular case is an instance of our intuitions being wrong. As far as we can tell from observing, the explanation for Swampy’s actions could just as easily be that he was created by a mad scientist for the express purpose of appearing to choke. Because of this, we shouldn’t put too much weight in the fact that Swampy appears to be exactly the same as Real Bush. That is, we shouldn’t say he has some particular function or another simply because of the limited facts we can directly observe.