1.2 – Presentism vs Eternalism

Thanks Onix, great topic.

I first want to get a bit of clarification. In discussing topics as complicated as this, I always attemt to reduce the ideas to a clean, simple definition or explaination of the problem. I am going to attempt to explain each of the two options as I currently see them. If you find a flaw, or have a better way of putting something, please correct me.

  • Presentism.
    • The idea that the only moments that exist are those we currently percieve. This means that the future does not exist, but will come to exist eventually. Likewise, the past does not exist. The past once did exist, but has since ceased to exist.
  • Eternalism.
    • The idea that all moments exist simultaneously. This means that the past, present, and future all occupy the same point of space-time, and are all occuring at once. The only reason time is linear to us is that we are only capable of percieving one moment at a time, thus we only percieve the flow of time, rather than it actually flowing.

Have my assumptions been correct, or can you offer any clarifying points that may help clearly define the subject?

– Jonah



2.1 – Personal Identity

The question is this: who am I metaphysically?

The question of “Who am I?” is a fascinating one with many different types of answers which we may discuss at length in the future. The type of answer that I care about today is the metaphysical one.

Suppose I have an identical twin, and we have lived a good, long life, staying close to each other throughout our lives and we are now 80 years old. We are looking through old photos surprised at how far we’ve come. In many of the photos, it is difficult to tell us apart, and even now, sometimes our grandchildren mistake us for each other. In many ways, my old self is more similar to my old twin than my old self is to my young self, and my young self is more similar to my young twin than my young self is to my old self. Despite this, it is very obvious that my young self is me. My young twin and I share memories, interests, a childly form and more that I don’t share with my younger self, and yet it seems ridiculous to consider that my young twin is me even close to the extent that I, my older self, am me, my younger self. Why is this? What ties me to my younger self?

This example shows that genetics isn’t the tie. My identical twin and I share the same genetics, and he is not me. It isn’t physical similarity either. You may have heard of the Ship of Theseus thought experiment. Suppose there is a ship, that slowly has its pieces replaced until all of its pieces are eventually different from when it was first built. Is it still the same ship? You may have also heard of the idea that all of the atoms in our body are replaced over some time (about a year, even though some cells like brain cells last a lifetime). So we are like the Ship of Theseus. You could say that you, I and the Ship of Theseus are made of fungible parts.

Fungibility is generally used as an economic term, but I’m adopting it for this conversation. It means that something is totally interchangeable. Any ordinary $5 bill has the same value as any other ordinary $5 bill and two $5 bills have the same value as a $10 bill. This means that bills are fungible. In the same way, atoms and ship parts are fungible. Swapping them around doesn’t have an effect, so even if you are a lot different in a year, you won’t literally be a different person.

Alright, so we’ve established some intuition about this matter, but now it’s time to get into some grittier stuff. Namely, why is a figurative Ship of Theseus still itself after any amount of time at all? Does it perdure or endure? Perdurantism is the idea that physical objects have temporal parts. A perdurantist would suppose that <you> are a sort of four-dimensional “snake” that has one end at the moment you come into being, the other end at the moment you no longer are, and a thickness of the shape of you. Endurantism is the idea that you exist wholly in the present at every moment, but the identity of you “endures” from moment to moment.

Again I will leave you, Jonah, with this introduction and the statement that I agree with the idea of perdurantism as opposed to endurantism.


Awaiting your response,


1.1 – Presentism vs Eternalism

The question is this: do the past and the future exist?

Philosophical presentism is the view that neither the future nor the past exist–only the present. Eternalism says that they all exist, even if the former two are inaccessible.

The problem is that is can’t be resolved empirically. There is nothing that says that any moment is now except that it is the moment that we are currently experiencing. Now is entirely subjective to our experience, so if one were to visit the past or the future, it would become now to the observer, and it would exist. The question is whether it exists before it was traveled to.

Since this discussion revolves heavily around the idea of time, it will be helpful to imagine that one could move freely through it. This is of course, time travel. Jonah and I will be discussing many of the different aspects of time and the consequences of traveling though it. We’ll mostly focus on metaphysics and philosophical ideas, but I’m sure we’ll broach the physics as well.

I’ll start off the discussion by siding with eternalism–that the future and past do exist, and we’ll go from there.


Awaiting your response,