This paper aims to discuss Parfit’s argument regarding personal identity in Reasons and Persons. I will first provide a reconstruction of Parfit’s dialectic, analyzing his motivation for including the three thought experiments, then moving to examine why he finds the shift in his opinion liberating as well as providing further evidence as to why I personally find his claims compelling. 

In Reasons and Persons, Parfit reaches the main conclusion that the most important part of our personal identities is not “uniqueness,” but rather, Relation-R (our psychological connectedness and continuity). In order to reach this conclusion, Parfit explores three different thought experiments: brain/body exchange, replication, and duplication. 

In the first thought experiment, Parfit attempts to first disprove that an individual’s identity depends on one’s body. Person A’s brain is put into person B’s body, vice versa. If A was asked to choose one body to torture, any rational human being — again, the readers are encouraged to empathize with A’s perspective — would choose to torture their original body with B’s brain. Here, Parfit presents two possible answers for our behavior: an individual’s identity is determined by either (i) one’s brain or (ii) one’s psychology. With the help of a simple simulation, Parfit proves with the reader’s own choice that psychological, not physical, continuity is what matters to our identity. 

Next, Parfit introduces the case of replication to refute the idea that our identity depends on our brain: what if we can make an exact replica of our brains to cure terminal illnesses? Here, then, the two brains are qualitatively the same (except for the removal of defect), but numerically different. In this case, Parfit argues that one’s positive reaction to the replication entails that our psychological continuity is what accounts for our identities. We can replace our brains with a qualitatively identical replica and still remain as the same person — our identity remains as long as we have Relation-R. 

Lastly, Parfit presents the duplication of individuals through teletransportation. In the future, we can travel across space by making an exact duplication of ourselves while destroying our original body. This example, in most cases, would cause the audience to contemplate as if they were in the situation. Is teletransportation a method of traveling or is it simply death for the original us? Parfit believes in the first option: duplication is as good as ordinary survival for us. In other words, he argues that we will continue to be the person we were before teletransportation because the past/future us are psychologically connected and continuous. 

Once he reaches this conclusion, Parfit argues in section 95 that his Reductionist view makes him feel “liberated,” in contrast to how he felt “trapped” when he believed in the Non-reductionist view like the majority of his audience. 

In section 95 of Reasons and Persons, Parfit assumes that “most of [the readers] are Non-Reductionists,” and that we “believe that our continued existence … must be all-or-nothing.” Parfit claims that their belief “is not true.” He continues to explain his reasons for this claim, appealing to the reader by empathizing with their perspectives — he was once also trapped in a “glass tunnel, though which [he] was moving faster every year, and at the end of which there was darkness.” In this sense, he states, death resembles darkness and utter loneliness.  

In earlier sections, Parfit explained personal identity as the combination of “uniqueness” and “Relation-R.” In this section, Parfit states that once he shifted his perspective from focusing on the effect of death on our “uniqueness” to its effect on “Relation-R,” he felt freed as if the glass wall of the tunnels had disappeared. In simple terms, instead of seeing his death as an event in which all of his legacies and experiences cease from existence, Parfit now understands death as his inability to have a direct impact on others and the world. For this epiphany, he feels liberated.

Just like Parfit’s assumption, I was indeed also one of the majority who believed in the Non-reductionist view about death. In a way, I’ve always thought of the life of each individual as a dissolving bath bomb in water — eventually, there will be nothing left. However, enlightened by Parfit’s perspective, my “glass tunnel” also disappeared. Even after the bath bomb completely dissolves, it still exists in another form with the water around it. The “death” of the bathbomb simply means that there no longer remains any original part of the bathbomb to continue adding new, raw material to the water. The bath bomb will continue to remain in the water, with all of its sediments sinking to the bottom eventually. 

In conclusion, as seen in the three thought experiments (brain/body exchange, replication, duplication), one’s identity isn’t dependent on their body/brain, rather, Relation-R is what constitutes our identity; Parfit’s argument can be further supported by my illustration of the bath bomb.