Free The Life of the Mind by Hannah Arendt Page A

inferred; the
cogito
is subject to the same doubt as the
sum.
The I-am is presupposed in the I-think; thought can seize on this presupposition but it can neither prove nor disprove it. (Kant's argument against Descartes was entirely right, too: The thought "
I am not
... cannot exist; for if I am not, it follows that I cannot become aware that I am not." 58 ) Reality cannot be derived; thought or reflection can accept or reject it, and the Cartesian doubt, starting from the notion of a
Dieu trompeur,
is but a sophisticated and veiled form of rejection. 59 It remained for Wittgenstein, who had set out to investigate "how much truth there is in solipsism" and thus became its most relevant contemporary representative, to formulate the existential delusion underlying all its theories: "At death the world does not alter, but comes to an end." "Death is not an event in life; we do not live our death." 60 This is the basic premise of all solipsistic thinking.
    Although everything that appears is perceived in the mode of it-seems-to-me, hence open to error and illusion, appearance as such carries with it a prior indication of
realness.
All sense experiences are normally accompanied by the additional, if usually mute, sensation of reality, and this despite the fact that none of our senses, taken in isolation, and no sense-object, taken out of context, can produce it. (Art therefore, which transforms sense-objects into thought-things, tears them first of all out of their context in order to de-realize and thus prepare them for their new and different function.)
    The reality of what I perceive is guaranteed by its worldly context, which includes others who perceive as I do, on the one hand, and by the working together of my five senses on the other. What since Thomas Aquinas we call common sense, the
sensus communis,
is a kind of sixth sense needed to keep my five senses together and guarantee that it is the same object that I see, touch, taste, smell, and hear; it is the "one faculty [that] extends to all objects of the five senses." 61 This same sense, a mysterious "sixth sense" 62 because it cannot be localized as a bodily organ, fits the sensations of my strictly private five senses—so private that sensations in their mere sensational quality and intensity are incommunicable—into a common world shared by others. The subjectivity of the it-seems-to-me is remedied by the fact that the same object also appears to others though its mode of appearance may be different. (It is the inter-subjectivity of the world, rather than similarity of physical appearance, that convinces men that they belong to the same species. Though each single object appears in a different perspective to each individual, the context in which it appears is the same for the whole species. In this sense, every animal species lives in a world of its own, and the individual animal does not need to compare its own physical characteristics with those of its fellow-members in order to recognize them as such.) In a world of appearances, filled with error and semblance, reality is guaranteed by this three-fold commonness: the five senses, utterly different from each other, have the same object in common; members of the same species have the context in common that endows every single object with its particular meaning; and all other sense-endowed beings, though perceiving this object from utterly different perspectives, agree on its identity. Out of this threefold commonness arises the
sensation
of reality.
    To each of our five senses corresponds a specific, sensorily perceptible property of the world. Our world is visible because we have vision, audible because we have hearing, touchable and full of odors and tastes because we have touch, smell, and taste. The sixth sense's corresponding worldly property is
realness,
and the difficulty with this property is that it cannot be perceived like other sensory properties. The sense of realness is not a sensation strictly