Perception

Are sensations real? That is, do they continue to exist when unperceived? It seems to me that objects that I perceive around me are both real (because outside my head) and composed of sensations: that is, they are structures of colours, tactile qualities, etc.; in which case these sensatations, as parts of real objects, are real. But it also seems obvious that sensations exist only while perceived, in which case they are not real.

Comments

Sensations are real in my book while I am having them, but you are right that it is not easy to use them to build a table. The trouble is that the table has a continuous existence, while it is only intermittently observed. One standard way around this problem is to fill in the apparently unobserved periods by having God observe the table all the time. That was George Berkeley's suggestion. Another way is to fill in the gaps between actual table sensations with merely possible sensation. This too is suggested by Berkeley in one remarkable passage, and figures centrally in John Stuart Mill's phenomenalism, acccoring to which tables are, in his memorable phrase, 'permanent possibilities of sensation'. The idea is that even when nobody is looking at the table, it is still true that if someone were to come into the office, they would see the table.

Phenomenalism is a clever solution to the gap problem, but like many other philosophers (not to mention ordinary people) I find it incredible to suppose that objects are built out of sensations, gappy or continuous, actual or potential. Sensations are in our heads, and sometimes caused by physical objects that are outside our heads and are not even partially made up of sensations. But the contrary, idealist perspective has certainly figured prominently in the history of philosophy.

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