Nikk Effingham

A Mereological Challenge to Endurantism

In this paper, we argue that time travel is problematic for the endurantist. For it appears to be possible, given time travel, to construct a wall out of a single time travelling brick. This commits the endurantist to one of the following: (a) the wall is composed of the time travelling brick many times over; (b) the wall does not in fact exist at all; (c) the wall is identical to the brick. We argue that each of these options is unsatisfactory.

Mereological Explanation and Time Travel

I have previously argued in a paper with Robson that a particular time travel scenario favours perdurantism over endurantism on the grounds that endurantists must give up on the Weak Supplementation Principle. Smith has responded, arguing that the reasons we provided are insufficient to warrant this conclusion. This paper agrees with that conclusion (for slightly different reasons: that even the perdurantist has to give up on the Weak Supplementation Principle) but argues that the old argument can be supplanted with a new one.

Universalism, Vagueness and Supersubstantivalism

Sider has a favourable view of supersubstantivalism (the thesis that all material objects are identical to the regions of spacetime that they occupy). This paper argues that given supersubstantivalism, Siders argument from vagueness for (mereological) universalism fails. I present Siders vagueness argument (§§II–III), and explain why – given supersubstantivalism – some but not all regions must be concrete in order for the argument to work (§IV). Given this restriction on what regions can be concrete, I give a reductio of Siders argument (§V). I conclude with some brief comments on why this is not simply an ad hominem against Sider, and why this incompatibility of supersubstantivalism with the argument from vagueness is of broader interest (§VI).

An unwelcome consequence of the Multiverse Thesis

The Multiverse Thesis is a proposed solution to the Grandfather Paradox. It is popular and well promulgated, found in fiction, philosophy and (most importantly) physics. I first offer a short explanation on behalf of its advocates as to why it qualifies as a theory of time travel (as opposed to mere ‘universe hopping’). Then I argue that the thesis nevertheless has an unwelcome consequence: that extended objects cannot travel in time. Whilst this does not demonstrate that the Multiverse Thesis is false, the consequence should give pause for concern. Even if it does not lead one to reject the thesis, I briefly detail some reasons to think it is interesting nonetheless.

Multiple studies and weak evidential defeat

When a study shows statistically significant correlation between an exposure and an outcome, the credence of a real connection between the two increases. Should that credence remain the same when it is discovered that further independent studies between the exposure and other independent outcomes were conducted? Matthew Kotzen argues that it should remain the same, even if the results of those further studies are discovered. However, we argue that it can differ dependent upon the results of the studies.

Properties are Potatoes? An Essay on Ontological Parsimony

The technique of cost/benefit analysis is standard fare in contemporary ontology: we measure how a theory performs along a variety of dimensions (simplicity, coherence with intuitions etc.) and then — having completed this for all theories currently being evaluated — we opt for the theory that has, overall, the best cost-benefit profile. Section 1 is a more detailed exposition of this methodology. One of those theoretical dimensions is ontological parsimony, and one common way of achieving it is ‘reduction by identification’ whereby an initial theory that commits to the Xs and the Ys has a more parsimonious rival according to which each X is one of the Ys (e.g. properties are identical to classes, possible worlds identical to disconnected spacetimes, material objects identical to space time regions etc.). This chapter argues that a theory achieving such ontological parsimony by this method is never a point in its favor — with the exception that it might, in general, push us towards a one-category ontology. This may be because you give up on ontological parsimony as a virtue or the tenability of making reductions by identification. Alternatively it may be because you agree that it’s a virtue and the reductions are tenable, but that the only thing you can draw from this is that we should endorse a one-category ontology. This chapter argues for the latter, although the other options — ditching either reduction by identification or parsimony as a virtue — are both lessons you may draw instead.