Mulligan's artful dodge when Stephen asks him whether he
remembers Stephen visiting him soon after his mother died—"I
remember only ideas and sensations"—appears to draw on 18th
century empiricist philosophy, which posited sensory origins
of all human knowledge. If so, then Mulligan is suggesting
that life is a flurry of changing sense perceptions and of the
concepts uncertainly inferred from them, with no firm grasp of
objects or events. In such a phenomenological storm, how could
he be expected to remember, much less be responsible for, a
friend's mother's death, a social encounter, a hurtful
utterance?
Thornton hears in Mulligan's sentence the influence of John
Locke. In book 4, chapter 11 of An Essay Concerning Human
Understanding, titled "Knowledge of the existence of
other things," Locke argues, "We can know of the existence
of other things only by sensation. No idea you have in your
mind has any necessary connection with any real existence
... Merely having the idea of a thing in your mind no more
proves its existence than the picture of a man is evidence of
his existence in the world, or than the visions of a dream
make a true history."
Locke's skepticism is not thoroughgoing. He believes that we
can be certain of our own existence, and of God's, and he is
persuaded that we can obtain useful knowledge of a world
external to our own minds. But he argues that every idea we
have about things outside us, including other human beings, is
drawn from sensations. These may well correspond to something
actual, but they do not do so necessarily or exactly.
Some 18th century philosophers drew from Locke's empiricist
epistemology the conclusion that reliable understanding of the
external world is impossible, since one knows only one’s
remembered "ideas" of subjective "sensations." Among the
entities effaced by such subjective skepticism are other
subjects, and Mulligan is happy to use a theoretical
explanation of such effacement as an excuse for self-centered
hedonism. He conveniently omits to mention any moral
sensations that might have formed in his consciousness as a
result of speaking so
callously about his friend.
Stephen too, in his very different way, shows interest in the
epistemological and ontological implications of Locke's
analysis. In Proteus he thinks thoughts inspired by
the Irish philosopher George
Berkeley, to the effect that perhaps no material world
exists outside his own mind. Berkeley's radical idealism
stands conspicuously opposed to the materialist philosophies
of most of Locke's followers, but it too stems from the
disjunction between sensations and objects that Locke
effected. Walking along the beach, Stephen regards his sensory
perceptions not as partially reliable impressions of material
objects but as "coloured signs" which can be read like text to
reveal an invisible, spiritual order of being.
The presence of Bishop Berkeley in Ulysses suggests
that it is quite possible that Mulligan has derived his view
of Lockean "ideas and sensations" from some intermediary
source. Gifford hears in the words “the essentially
mechanistic concept of the human psyche developed by the
English philosopher David Hartley (1705-57)” under Locke's
influence. The Scottish philosopher David Hume's
investigations were also shaped by the great English forebear.