The Criteria of Personal Identity

Source

For a number of reasons, I think that knowing and thinking about personal identity are some of the most important and significant things to do/achieve in life. The obvious reason is that we ought to think about our own existence and what makes us humans. Second is that deciding on a criterion of personal identity leads us to possibly decide on many conflicting moral questions.

For example, in the case of abortion, there are debates on whether a foetus is an alive human being or not. Further, there are conflicting views on exactly when a foetus becomes a human - when conceived? at a certain age?

In the coming weeks, I will be posting about different criteria of personal identity, including bodily criterion, soul/Cartesian ego, memory + psychological connection view, and so on.

However, first, we should understand what a criterion or a principle of personal identity is.
In my understanding, it is 'a thing, property or fact in virtue of which two people existing at different times are numerically identical', meaning that the criterion determines whether A and B at different times (e.g. past and present, present and future) are the same person.

Now, what does it mean to be 'numerically identical'? To understand this, I shall compare it to being 'qualitatively identical'. Being qualitatively identical means that A and B are duplicates, that is, A and B are exactly similar in all respects. In other words, A and B have all qualitative properties in common. For example, two pens made in the same pen factory on the same production line share exactly similar qualitative properties.
Being numerically identical, on the other hand, means that A and B are one and the same thing.

Now, back to the topic of abortion and the identity of the foetus. We need to decide on what we believe to be the ultimate criterion of the identity and existence of a human being in order to conclude whether abortion is in fact murder or not.

In my next post, I will discuss the bodily criterion of personal identity and consider the pros and cons of accepting that view. And hopefully by the end of this long discussion, I will have learnt and thought more about personal identity and perhaps decide on one with which I agree the most.