Bishop Berkeley Said Matter Does Not Exist

George Berkeley, Bishop of Cloyne, published A Treatise Concerning the Principles of Human Knowledge in 1710 with a central thesis that still stops readers cold: material substance does not exist. There are minds, and there are ideas in minds, and that is all.

His argument, compressed: we only ever experience our own perceptions. When you see a table, you are experiencing a visual impression. When you touch it, you experience a tactile impression. You have never experienced the table itself — only the sensory ideas it produces. Berkeley concluded there is no reason to posit an unperceived thing underneath those impressions. The table just is the collection of ideas a mind has when it attends to the table.

Esse est percipi — to be is to be perceived — was his formula. The obvious objection is: what happens to the table when no one is looking at it? Berkeley's answer was God. God perceives everything at all times, so nothing ceases to exist when humans stop attending to it. This moves the argument from metaphysics into theology, which is one reason it has always made materialists uncomfortable.

In 1763, James Boswell watched Samuel Johnson kick a large stone with his foot and declare, 'I refute it thus.' The line is famous; the refutation is not. Johnson's kick only proves that the stone produces a certain kind of forceful sensory impression in a certain kind of mind. Berkeley would say that is exactly his point: the stone exists as an idea, and a powerful one.

What Berkeley's argument does force you to do is explain what 'the external world' actually refers to, if not to your own experience of it. Most people find this uncomfortable to pursue for very long — which is, arguably, why materialism remains the default.