The essential problem with his argument is the series of infinite regression that it implies (BonJour 283). In order to understand this explanation, one needs to know how Frankfurt defines second-order desires and second-order volitions. A second-order desire is defined as the wanting to have or not to have certain desires or motives. A second-order volition would be when a man “wants a certain desire to be his will” (BonJour 277). Frankfurt is saying that for a man to truly have free will and therefore be considered a person, he would have to have control over these second-order desires and volitions. If one accepts the existence of such orders of desires, one would begin to question exactly how many of them exist. Are there third-order desires that lead to second-order desires? Are there fourth-order desires? And so on. If all these higher numbered desires are determining all lower number desires, when does the man have free will at all? Now, it is easy to see how this infinite regression can serve a problem to the concept of free will. In a sense, the regression problem supports determinism – a view that all of a man’s desires have already been determined for him. If we therefore assume that no man has free will and free will is the only determinate as to what makes a person, then there are no people. The question of what makes a person then becomes moot. If Frankfurt would want to argue that there is at least one person in the world, then he would have to disagree with his own argument because of the problem of regression. Luckily, he includes later in his argument the condition of rationality in the definition of personhood. However, Frankfurt states that “the structure of a person’s will presupposes, accordingly, that he is a rational being” (BonJour 278). This hardly reconciles the problem previously discussed. The following argument structure follows this statement when taking the problem of regression into account:
If a man is a rational being, then the man has free will.
No one has free will.
Therefore, No one is a rational being.
Using modus tollens, it follows that no one would have reason and no one would have free will. This would therefore conclude that no one is a person.
Thankfully, this problem can be easily rectified by including other characteristics to the definition of “person.” Frankfurt has already rejected the idea that “person” should be used in a species-specific manner. However, if one could combine certain species-specific characteristics, free will, and rationality, then it is possible to create a good definition of “person” that does not fall prey to the regression problem. Thus, I will reject what is implied in Frankfurt’s thesis and in the first premise of the first argument discussed. Mentioning one characteristic is not enough to fully satisfy a definition. A clear example of this would be the multiple explanations dictionaries give for most words within its tome. One could not completely understand what "hat" means if one was only exposed to one characteristic of a hat. The same can be said for more complex definitions, such as "person."