### Conceivability Arguments for Dualism, Part II: Stoljar's Critique of David Chalmers' Argument

Notes on Daniel Stoljar's “The Conceivability Argument and Two Conceptions of the Physical” (Phil. Perspectives 15, 2001)

In this paper, Stoljar attacks Chalmers’ conceivability argument for property dualism. Recall that the conceivability argument runs as follows:

1. It is conceivable that I have a zombie-twin, i.e., someone physically identical to me and yet who lacks phenomenal consciousness.
2. If it is conceivable that I have a zombie-twin, then it is possible that I have a zombie-twin.
3. If it is possible that I have a zombie-twin, then physicalism is false.
4. Therefore, physicalism is false.

In addition to his t-physical/o-physical property distinction, Stoljar brings in Van Cleve’s weak/strong conceivability distinction. Weak conceivability is the inability to conceive that P is impossible, and strong conceivability is the ability to conceive that P is possible. Among other problems, the former allows that Goldbach’s Conjecture both is and isn’t conceivable, in which case it is not a reliable guide to possibility. Goldbach’s Conjecture isn’t strongly conceivable, however, and therefore (in conjunction with other virtues) strong conceivability provides prima facie justification for modal propositions.

Stoljar brings these two distinctions to bear upon Chalmers’ conceivability argument by using them to construct a dilemma against it: Start off with the assumption that “conceivable” is intended to be read as “strongly conceivable” throughout Chalmers’ argument. Then:

1. Either “the physical facts” are to be read throughout the argument as “the t-physical facts” or as “the o-physical facts”.
2. If they are to be read as “the t-physical facts”, then although the argument is valid, we have no reason to think it is sound. For the extra, o-physical facts, when combined with the t-physical facts, may then metaphysically necessitate that the twin is not a zombie, in which case (3) would be false.
3. If they are to be read as “the o-physical facts”, then the argument is invalid. For then ‘conceivable’ in (1) can only be truly read as ‘weakly conceivable’ (in which case there is an equivocation in the use of “conceivable” between (1) and (2)).
4. Therefore, either the argument is invalid, or we have no reason to think it is sound.

In short, Chalmers’ argument fails by artificially limiting the consciousness-relevant properties to t-physical properties.

*Stoljar’s own position is “o-physicalism” – the view that physical objects have o-physical properties in addition to their t-physical properties – which is, roughly, a modern version of Russell’s neutral monism.

Thoughts said…
The Knowledge Argument is much simpler when expressed in scientific terminology (see Superscientist Mary and types of physicalism.) Do you ever get the feeling that philosophers want all the answers now, immediately, and don't have the patience to wait until we understand the world a bit better?

### Epicurean Cosmological Arguments for Matter's Necessity

One can find, through the writings of Lucretius, a powerful yet simple Epicurean argument for matter's (factual or metaphysical) necessity. In simplest terms, the argument is that since matter exists, and since nothing can come from nothing, matter is eternal and uncreated, and is therefore at least a factually necessary being.
A stronger version of Epicurus' core argument can be developed by adding an appeal to something in the neighborhood of origin essentialism. The basic line of reasoning here is that being uncreated is an essential property of matter, and thus that the matter at the actual world is essentially uncreated.
Yet stronger versions of the argument could go on from there by appealing to the principle of sufficient reason to argue that whatever plays the role of being eternal and essentially uncreated does not vary from world to world, and thus that matter is a metaphysically necessary being.
It seems to me that this broadly Epicurean line of reasoning is a co…

### CfP: Inquiry: New Work on the Existence of God

NEW WORK ON THE EXISTENCE OF GOD
In recent years, methods and concepts in logic, metaphysics and epistemology have become more and more sophisticated. For example, much new, subtle and interesting work has been done on modality, grounding, explanation and infinity, in both logic, metaphysics as well as epistemology. The three classical arguments for the existence of God – ontological arguments, cosmological arguments and fine-tuning arguments – all turn on issues of modality, grounding, explanation and infinity. In light of recent work, these arguments can - and to some extent have - become more sophisticated as well. Inquiry hereby calls for new and original papers in the intersection of recent work in logic, metaphysics and epistemology and the three main types of arguments for the existence of God.

The deadline is 31 January 2017. Direct queries to einar.d.bohn at uia.no.

### Andrew Moon's New Paper on Recent Work in Reformed Epistemology...

...in the latest issue of Philosophy Compass. Here's the abstract:
Reformed epistemology, roughly, is the thesis that religious belief can be rational without argument. After providing some background, I present Plantinga's defense of reformed epistemology and its influence on religious debunking arguments. I then discuss three objections to Plantinga's arguments that arise from the following topics: skeptical theism, cognitive science of religion, and basicality. I then show how reformed epistemology has recently been undergirded by a number of epistemological theories, including phenomenal conservatism and virtue epistemology. I end by noting that a good objection to reformed epistemology must criticize either a substantive epistemological theory or the application of that theory to religious belief; I also show that the famous Great Pumpkin Objection is an example of the former. And if a copy should make its way to my inbox...

UPDATE: Thanks!