Kelly asked:

I have been studying the Argument From Design as outlined by Hume in his Dialogues Concerning
Natural Religion. When compared to his Argument From Vegetation, which would you say is more
plausible and why?

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Hume's argument that we have as much reason to believe that the universe grew like a vegetable as
we have to believe that the universe was designed by God is an ad hominemargument (from the
Latin 'against the man'). As students are often thrown by ad hominem arguments, your question is
very instructive.

At first sight, it seems an appalling lapse on Hume's part to overlook the possibility that the process of
growing from acorn into an oak tree itself requires explanation in terms of a hidden, highly intricate
design (an explanation we should now give in terms of genetics and developmental biology). A theist
would say that this was a perfect example of the kind of thing that can only be explained by the
handiwork of God. You have to be pretty thick not to be amazed at the way such an insignificant
seeming object as an acorn can take on such an impressive form as an oak.

As an explanation of how there can exist a universe with all the characteristic marks of design, the
Vegetation theory begs the very question at issue.

However, I do not believe for one minute that Hume thought the Vegetation theory explainedhow
there comes to be design in the universe. He is arguing ad hominem. The 'man' in this case is William
Paley who claimed that if we found a watch lying on the ground, it would be absurd to suppose that
the intricate structure came together by accident. The only creditable explanation is that the watch
was made by a skilled craftsman. The universe itself can be compared to a giant watch, which
exhibits far greater order and intricacy of structure. So it too must have been designed by an
intelligent Creator, whose power exceeds that of a human watch maker to the same degree as the
order and intricacy of the universe exceeds that of a watch.

Hume's response is to say, in effect: “If you are going by experience,then just as experience teaches
us that watches are made by watch makers, so it teaches us that acorns grow naturally from oaks.
On the basis of experience, therefore, we have just as much ground for believing that the universe
grew like an oak, as we have for believing that it was designed by a great Watch Maker.”

This does not refute the belief that the universe could only have come into being by design. It refutes
one particular version — or, perhaps not even that, but rather one particular interpretation of one
version — of the Argument from Design.

Geoffrey Klempner