Dorianne asked:

What did the person who hit a stone and said ‘I refute him thus’ while disagreeing with Berekely mean by that action?

Answer by Martin Jenkins

Dr Johnson reputedly kicked the stone to demonstrate that the stone was a real, material thing existing independently of him – the epistemological view of Naive Realism. By this act he hoped to refute Berkely’s philosophical doctrine of Immaterialism.


In his Of the Principles of Human Knowledge, Bishop George Berkeley begins by stating that human knowledge is derived from either ‘Ideas imprinted on the senses or perceived by attending to the passions and operations of the Mind or, the ‘compounding, the dividing of ideas by memory, by Imagination’ (#1, Principles).

There is something that knows or perceives the ideas, which wills, imagines, remembers.

“This perceiving, active being is what I call mind, spirit or soul or my self. By which words I do not denote any one of my ideas but a thing entirely distinct from them, wherin they exist, or which is the same thing – whereby they are perceived; for the existence of an idea consists in being perceived.” #2

There exists only ideas, sensations and minds which have those ideas, those sensations. This is contra to ‘common sense’! What we perceive are ideas granted but, these are copies, representations, reflections of actual, independently existing material objects, things in the world.

The ‘common sense’ materialist view involves, upon examination, a manifest contradiction. It maintains that houses, mountains, rivers exist or have independent existence distinct from their being perceived. If however, we perceive only Ideas, sensations; ideas and sensations can only exist when being perceived by the Mind. Ideas cannot exist apart from, independently of a Mind. So, Ideas exist only when perceived by a Mind. As Berekely famously summarised: Esse est Percipi — to be, is to be perceived.

No! The Ideas, sensations are only ideas etc of underlying things, objects. Just because we do not have an idea of a thing, object; it does not follow that we can then conclude that the object itself does not exist. A conclusion of ontology does not follow from a conclusion of epistemology.

Berkeley is most insistent that Ideas cannot be representatives of objects underlying or causing them. For we only ever perceive Ideas. Even if we had an Idea of an underlying object, this would be another Idea, an Idea to be contrasted with another Idea and so on ad infinitum. (#8 et alibi) No underlying physical object existing independently of a perceiving Mind can ever be reached. He lays down his challenge: is it conceivable for Ideas to exist independently of perceiving Minds?

“This easy trial may take you to see what you contend for is a downright contradiction. Inso much that I am content to put the whole upon this issue; if you can but conceive it possible for one extended, movable substance or, in general for any one Idea or anything like an Idea to exist Otherwise than in a perceiving mind; I shall readily give up the cause…” #22

So Dorianne, when Dr Johnson kicked the stone, he had the Idea of the stone, the sensations accompanying his kicking it but, as these remain Ideas, sensations in his Mind and the Mind of his companion with whom he was discussing the Bishop; he has not refuted Berkeley’s thesis. He is verifying it.