Presentism makes a claim about what exists: present things are real, while past and future things do not belong to reality in the same unrestricted sense. Understanding that claim requires more than saying that we observe the world now.
Existence and access
Ned Markosian's A Defense of Presentism begins by distinguishing the things that exist from things that merely existed or will exist. The position is not just a restriction on what an observer can currently see. It is a proposed account of existence itself.
That distinction matters because a rival can agree that observation occurs at the observer's present location and time. A historian examining an old document has a present encounter with a record. Whether the event recorded also exists in a broader temporal reality is a further question.
Consider a photograph of a demolished building. Three claims need separating: the photograph exists now; a building existed when the photograph was taken; the past building exists tenselessly. The first two do not by themselves settle the third. Presentism accepts ordinary truths about the past while disputing a particular ontological reading of them.
Truths about the past
A familiar challenge asks what makes a true statement about a vanished event true. Present records may provide evidence, but evidence and truth are different roles. A record can be lost while the assertion that an event occurred remains true. A forged record can exist while its assertion is false.
As a thought experiment, imagine two laboratories with identical present notebooks. In one laboratory the entries accurately report an experiment; in the other they were fabricated. The notebooks alone do not determine the difference between those histories. The example does not refute presentism. It identifies a task for an account of past truth and for an account of historical knowledge.
Keep this challenge distinct from an engineering problem about storage. A larger database can preserve more evidence, but increasing its capacity does not automatically resolve the metaphysical status of what the evidence describes.
Which present?
Relativity makes a universal present difficult to identify with the simultaneity surfaces of every inertial observer. Markosian explicitly discusses this challenge and distinguishes empirical commitments from additional metaphysical commitments in assessing possible responses. His defence is an argument within that debate, not a new experimental result.
A simple calculation shows the physical issue. In units with c = 1, consider two events with differences Δt = 0 and Δx = 2. A Lorentz boost with speed parameter β = 0.6 has γ = 1.25 and gives Δt′ = γ(Δt − βΔx) = −1.5. The events simultaneous in the first frame are not simultaneous in the second.
The calculation constrains a proposed global present; it does not, without further philosophical premises, select one complete ontology of time. A theory adding a preferred slicing must explain its status and whether it changes any observable prediction. Merely labelling a hidden variable presentness does not perform that work.
Local records and global claims
An observer's immediate record is not a photograph of a universal instantaneous world. Signals arrive after propagation, instruments integrate over finite intervals, and different clocks need an agreed comparison procedure. The existing essay on simultaneity develops these operational distinctions.
One can therefore ask two independent questions: which information is available to a completed observation, and which events exist? An operational restriction on access does not by itself establish presentism. Nor does inaccessible information automatically establish a separate realm of existing events.
The dual-time question
The SMM/DTT proposal distinguishes inner generative activity from outer records. Its condition for unobservable inner ordering asks whether changes of schedule survive any admitted future test. That mathematical condition should not be equated with a privileged observable present.
A comparison with presentism must state what the programme claims exists, what a completion makes accessible and how relativistic clock relations emerge. These are related questions, but they require different arguments. The comparison becomes informative when it exposes an additional premise or an observable restriction, rather than merely pairing the words creation and present.
Sources and further reading
- Ned Markosian, A Defense of Presentism, Oxford Studies in Metaphysics 1 (2004), 47–82, especially sections 1, 2.3 and 3.9. Author-hosted copy of the published chapter.
- Mohamed Haj Yousef, When inner order becomes unobservable.