arguments for God's existence, particularly Leibniz's
cosmological argument:

     (a) The world contains an infinite sequence of contingent

     facts;

     (b) An explanation is needed as to the origin of this whole

     infinite series, which goes beyond an explanation of each

     member in the series;

     (c) The explanation of this whole series cannot reside in

     the series itself, since the very fact of its existence

     would still need an explanation (principle of sufficient

     reason)

     (d) Therefore, there is a necessary substance which produced

     this infinite series, and which is the complete explanation

     of its own existence as well.

Earlier defenders of cosmological-type arguments, such as
Aquinas, argued that an infinite series of causes of the universe
is impossible. Thus, a first divine cause is required to start
this series of individual causes. However, Demea (and Leibniz)
assume that an infinite series of causes of the universe is
possible. Even so, Demea argues, we still need an explanation of
the entire collection of finite causes, which must be found
outside of the infinite collection of individual causes.

     Finally, a character named Philo is a skeptic who argues
against both a posteriori and a priori proofs. Philo offers a
stream of criticisms against the design argument, many of which
are now standard in discussions of the issue. For Philo, the
design argument is based on a faulty analogy: we don't know
whether the order in nature was the result of design since,
unlike our experience with the creation of machines, we did not
witness the formation of the world. The vastness of the universe
also weakens any comparison with a human artifacts: although the
universe is orderly here, it may be chaotic elsewhere. Similarly,
if intelligent design is exhibited only in a small fraction of
the universe, then we can not say it is the productive force of
the whole universe. Philo also contends that natural design may
be accounted for by nature alone, insofar as matter contains
within itself a principle of order. And even if the design of the
universe is of divine origin, we are not justified in concluding
that this divine cause is a single, all powerful, or all good
being. As to the cosmological argument, Philo argues that once we
have a sufficient explanation for each particular fact in the
infinite sequence of facts, it makes no sense to inquire about
the origin of the collection of these facts. That is, once we
adequately account for each individual fact, this constitutes a
sufficient explanation of the whole collection.

     The three characters in Hume's Dialogues are loosely based
on characters in Cicero's classic dialog, On the Nature of the
Gods and we may reasonably assume that Hume's audience recognized
this. In Cicero's dialog, a character named Cotta was a religious
skeptic, and his teacher was named Philo. Second, a character
named Balbus voiced an orthodox Stoic view of the gods, and
Balbus's teacher was named Cleanthes. Finally a character named
Velleius presented a third Epicurean view. Cicero himself
introduced and concluded his dialog, declaring Balbus the winner.
In Hume's dialog, too, the narrator declares the orthodox
Cleanthes the winner over the skeptical Philo. For Cicero, the
main issue of the dialog is not so much the existence of the
gods, but the nature of the gods, and whether they intervene.
However, for Hume the existence of God is the most prominent
issue.

     PUBLICATION OF THE DIALOGUES. Hume began work on the
Dialogues in about 1751. He apparently revised the manuscript
about 10 years later, and probably again in 1776 prior to his
death. During the last few months of his life, Hume scrambled to
make arrangements for the publication of his manuscript, which
ultimately appeared in print three years later in 1779. For more
than 100 years, the 1779 publication was the basis for other
printed editions of the Dialogues. However, because Hume did not
oversee the 1779 publication, more recent editions return to the
original manuscript, which is in the possession of the Royal
Society of Edinburgh and is currently available on microfilm.
Differences between the 1779 edition and more recent ones are
insignificant, although recent editions contain annotations which
describe the various revisions Hume made to the manuscript. In
his correspondences, Hume left an interesting paper trail
pertaining to the composition and ultimate publication of the
Dialogues. The first indication of the manuscript is in the
following letter to Gilbert Elliot of Minto, in which Hume asks
Elliot to review some "sample" parts of the manuscript (probably
Parts 1-4 from the final 12 sections):

     You wou'd perceive by the Sample I have given you, that I

     make Cleanthes the Hero of the Dialogue. Whatever you can