his mathematical notebooks and his New Theory of Vision (1709), the very
topic on which Newton had published his most popular book, Opticks, in
1704.^25
With Berkeley, the scientific philosophy turned into an attack on science.
Empiricism was pushed to an extreme and used as a weapon against materi-
alism. Berkeley criticized the current doctrines of optical science, extending
Locke’s empiricism and frequently using Molyneux’s hypothetical blind man.
The mathematical explanations of how distance and magnitude are perceived
depend on calculating angles of light rays at the eye. Berkeley appeals to
experience that we have no such consciousness of rays and calculations. Ge-
ometry itself is unreal when it goes beyond experience to points without
dimension and lights without breadth. And since there is always a minimum
visible object, microscopes are not really an improvement on normal sight;
they show us a different world, one that no longer has any connection with
the objects we know by touch. Every different sense gives its own experiences
and ideas. Our conception that there is an object uniting all the senses is only
a prejudice, resulting from language which applies a common word to experi-
ences which have usually gone together. Berkeley’s extreme phenomenalism
takes the world of experience apart into separate streams; he accepts Locke’s
method but demands it remain consistent and admit no further entities.
That Berkeley was counterattacking science in the name of religion is
apparent from the publications which followed hard on the New Theory of
Vision. His Principles of Human Knowledge (1710) declares in its subtitle that
it examines “the grounds of skepticism, atheism and irreligion,” and he an-
nounces the same thing in the title of his Three Dialogues between Hylas and
Philonous, in Opposition to Sceptics and Atheists (1713). Berkeley was a
clergyman, holding a succession of clerical posts and ending as a bishop. The
great plan of his life was to found a missionary college in Bermuda from which
to evangelize the Americas for the Anglican Church. He attacked Locke and
his followers as leading to Deism, now polemically equated with atheism.
Berkeley took apart the scientific doctrine of primary and secondary qualities,
a guidepost of materialist research since Galileo. For him the primary qualities
of pure extension do not exist; experience shows us sensations which always
have color and other “secondary” qualities. There is no material world of
primary qualities behind those we experience; this conception arises only from
an error based on false use of words—Locke’s critique of false names, but
pushed far beyond Locke’s purposes. Berkeley then turns his pure phenomenal-
ism into an argument for God: if experience shows consistency, it is because
God is always there presenting human minds with coherent experiences.
This anti-scientific turn within the intellectual network which had hitherto
been dominated by scientists was not an isolated incident. Berkeley’s principal
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