Tuesday, April 23, 2019

Presentism and vagueness

If presentism is true, then vagueness about the exact moment of cessation of existence implies vagueness about existence: for if it is vague whether an object has ceased to exist at t, then at time t it was, is or will be vague whether the object exists. But it is plausible that there is vagueness about the exact moment of cessation of existence for typical organisms (horses, trees, etc.). On the other hand, vagueness about existence seems to be a more serious logical problem: it makes unrestricted quantifiers vague.

Of course, the eternalist will have a similar problem with vagueness about existence-at-t. But existence-at-t is not fundamental logical existence on eternalism, so perhaps the problem is less serious.


Red said...

You hold to some ignorance theory of vagueness, true?

Alexander R Pruss said...

I do. And the presentist can do that, too.

StardustyPsyche said...

Material persists, material is conserved, so there is no need to identify when material comes into existence.

Material does not come into existence and it does not pass away from existence.

Relative organizations come into their relative states and pass away from their relative states. Organization itself is not an existent thing, rather, it is a real relationship between existent material.

A particular relationship between material is the case only in the present moment. Prior to this present moment material was organized differently, and after this present moment material will be organized differently still.

The material of an object does not come into or pass away from existence. What we identify as a particular object is an ever changing state of relative arrangement of conserved material.

In science the present moment in a process over time is defined as dt, or the limit as delta t goes to zero. The notions of infinitesimal and fluxion were used in the days of Leibniz and Newton and were not rigorously defined in their day. After centuries of work on continuity and limits the Calculus is now generally considered to be rigorously sound.

Ed Feser provided a link you your site. I have posted on the subject of defining t precisely here

I will copy a short bit of my arguments below


But what is “the present”? If one asserts that observation in the present necessitates god, shouldn’t the most accurate description available for “the present” be stated clearly?
Is it
t = 0
t = the infinitesimal
t = the limit as delta t goes to 0
t = t2 – t1

If “the present” is t = 0 then a moving object is at any particular point in the present for 0 time. That seems to be a way of saying the object is never at that point, yet we see the object move through that point.

If “the present” is t = t2 – t1 then what is the smallest value of t one can state, and isn’t any particular choice for t arbitrary?

So, we arrive at what Leibniz called the infinitesimal, which was later replaced by the limit as the foundation of modern descriptions of “the present” in time dependent processes