Personal Identity. In Christ.

"Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come." (2 Corinthians 5:17)

Today's post is about personal identity. I specifically want to focus on the question of how we know someone is the same person they were in the past. In other words, how am I the same person I was when I was 10?

Philosophers like to use thought experiments to clarify difficult concepts. Derek Parfit uses thought experiments to illustrate what is required for someone to be identical to a person in the past.

The thought experiment is this: Imagine someone had a brain transplant. Their brain was transplanted into someone else's body. The person who wakes up after surgery has all of the same memories, character traits, beliefs, and desires. Their last memory is of being put to sleep before surgery and wake up to the doctor informing them that the surgery was a success. Is this the same person as the person before the surgery?

The common response to this question is yes. Most people can imagine that a person can survive a brain transplant, waking up to inhabiting a different body. I don't think I have this intuition, but since many do, I'll assume it.

What I'm really interested in determining is how we judge whether the person has survived the transplant. Apparently Parfit's qualifications are that they share memories, character traits, beliefs, and intentions. Certainly these are important factors we would use to judge whether the person had survived the transplant. 

The Bible tells us that Christians receive a new identity in Christ. So if our identity is made up of memories, character traits, beliefs and desires, what does it mean to have our identity in Christ? I'd like to suggest that receiving an identity in Christ means receiving new character traits, beliefs and desires. It also involves a transformation of our memories from being about ourselves to being about Christ and his sovereignty in our lives. So, unlike the person who survives the brain transplant, the person who accepts God's offer of salvation is transformed and no longer the same person.

But are memories, character traits, beliefs, and intentions the only essential properties of personhood? Let's consider another thought experiment, offered by another philosopher, Donald Davidson. (Warning: philosophical thought experiments are often fantastical in nature)

Imagine that you go outside and get struck by lightning and die. At the same time, a windstorm hits a swamp and molecules get arranged in the same way and form as you had. The result is a person who has all of your memories, character traits, beliefs, and intentions. This person walks out of the swamp looking just like you, and since they have all of the same memories, they believe that they are you. They walk to your home, talk and act just like you, interact with the people you know just like you would and live your life. Is this person the same person as the person who was struck by lightning?

The common response to this question is no. So if Swampman has your same memories, character traits, beliefs and desires, what does he lack that makes him distinct from you? My answer to an audience of philosophers is agency. My real answer is the soul. By both of these answers I mean the aspect of a person that has the power to act as a unique individual and be autonomous. Although Swampman shares the same psychology as the person who died by lightning, they do not share the same power to act.

So when we receive new identity in Christ, not only does our psychology change, but our actions will change, too. 

"By this we may know that we are in him: whoever says he abides in him ought to walk in the same way in which he walked." (1 John 2:5b-6)