Posts tagged ‘modal logic’

April 21st, 2013

The Reverse Ontological Argument

by Max Andrews

Interestingly, there is an argument used by atheists to demonstrate that God is impossible, which picks up on the ontological argument. This argument is traditionally called the reverse ontological argument. Instead of demonstrating that God a maximally great being that exists necessarily, the reverse form is used to demonstrate that God is impossible. To give a context for the atheistic argument here are the two most popular versions of the theistic ontological argument:

The Anselmian Ontological Argument (Theistic)

  1. God exists in the understanding
  2. God is a possible being
  3. If X exists only in the understanding and is a possible being, then X might have been greater
  4. Suppose God exists only in the understanding
  5. God might have been greater (2, 4, 3)
  6. God is a being than which a greater is not possible
  7. So, a being than which nothing greater is not possible is a being which is greater is possible
  8. Since 4 led to a contradiction 4 must be false
  9. God exists not only in the understanding alone—God exists in reality as well
    read more »

February 15th, 2013

Is This a Possible World?

by Max Andrews

So, I gave a pop quiz to my class today because I asked them if they had any questions about any of the material we’ve been recently going over (logic) and no one had any questions. Because of their confidence I gave them a quiz, which resulted in very interesting answers. One of the questions was to describe some possible world. Simple enough, right? If they knew what a possible world was they could write something simple down like “there are pink elephants” or “my shirt is red instead of blue.” However, I got this very interesting one that made me think. Think about it and let me know how you would respond to this scenario. It assumes a lot about knowledge, minds, God, etc.

In a possible world there is no predictability. Nothing that happens once happens again a second time. There is no way to know what is going to happen but there is also no such thing as knowing because there is nobody to know anything since a being would require repeated processes to function and remain functioning.

May 23rd, 2012

Critiquing an Objection to the Cosmological Argument

by Max Andrews

Neill Shenton recently did a review/response to one of Doug Beaumont’s arguments for the existence of God.  Doug’s argument is the ususal Thomastic cosmological argument from contingency.  At this point I’ll assume that you’ve read the two posts so you’ve got a greater context for what follows.

Here’s Shenton:

This is an argument that keeps coming up & folk tweet responses but my thoughts don’t fit in a tweet so here’s my ramblings on the topic. 

I see this as a rather futile attempt to “prove” there is a god by a logic that depends upon definitions of the terms.  The key words here are ‘being’ and, not surprisingly, ‘god’.  If we substitute these words the futility is exposed.

  1. A widget exists
  2. Widgets cannot spontaneously come into existence, they have to be “made” by something that came beforehand.
3. If our widget was made by or evolved from another, and so on, where did the first widget come from?
4. Some none-widget-like-process made the first widget
5. I’m calling that “f’narg”
6. What do we know about F’narg? Nothing except it isn’t a widget by definition.  Is it god?  You could call it that, I’ll stick to f’narg; it has NO connotations.  So, we now know exactly what we already did, all this widgety universe started with something and now it has a name, f’narg

What Shenton is doing here is that he’s completely ignoring the modal status of the terms ‘contingent’ and ‘necessary’ in the original Thomistic argument.  This isn’t that big of a deal but for him to completely dismiss it isn’t critiquing the argument on its own grounds.  He’s changing the argument (straw man).  P3 is obviously a misunderstanding of the argument. 

May 23rd, 2012

Word of the Week Wednesday: Plantingan Modal Realism

by Max Andrews

Word of the Week: Plantingan Modal Realism

Defininition:  The modal metaphyiscs of Alvin Plantinga.

More about the word:  Contra to mere theisitic modal realism  and their doctrines Alvin Plantinga includes a commitment to a very large modal reality. Any object that has an accidental property in any world w–say, property of being the world’s tallest man–also has the modal property of being possibly the world’s fastest human and the modal property of being necessarily the world’s fastest human in w.  For every concredete object x there is some property P and some world w wuch that w includes x’s having P.  For Plantinga’s modal realism, abstract worlds are abstract objects. In theistic modal realism each possible world is the mereological sum of its parts.  These parts are themseves concrete individuals with spatiotemporal properties.  Plantinga’s modal realism does not necessarily entail multiverse scenarios. (For more see Michale Almaeida’s, Metaphysics of Perfect Beings, 140-50.)

March 28th, 2012

Word of the Week Wednesday: Modal Realism

by Max Andrews

The Word of the Week is: Modal Realism

Definition: Modal realism is the idea that all modal possibilities are actual.

More about the term:  Anything that is possible actually happens.  However, modal realism is, in a sense, modally limited.  The state of affairs of the non-existence of anything cannot be true if something does exist so by definition modal realism must entail ~∃!W with W being the non-existence of anything—nothing, lest it suffer the consequence of being intrinsically incoherent (~∃!W = There does not exist just one W).  In order to avoid an inherent incoherence perhaps there are logically antecedent reasons to affirm ~∃!W (i.e. actuality is logically prior to possibility, which makes possibility somewhat superfluous). Under certain multiverse scenarios different regions of space will exhibit different effective laws of physics (i.e. difference constants, dimensionality, particle content, relation of information, information propagation, etc.) corresponding to different local minima in a landscape of possibilities.[1]