George Berkeley is the leading idealist philosopher.

Idealism is the belief that ideas (thoughts) are the only reality.

This stems from Descartes.

Descartes wanted proof that he actually existed.

Definite, unarguable proof.

So Descartes doubted everything until proved otherwise.

But everything crumbled before doubt.

Descartes couldn’t prove the world outside his head existed, it might be an illusion.

Descartes couldn’t even prove his head existed, it might be an illusion.

Was there anything that wasn’t capable of being doubted?

Then it occurred to him.

He was thinking, doubting, everything.

So thinking was going on.

So someone must be there to experience the thinking.

That was the only thing he couldn’t doubt.

Consequently his famous quote “Cogito ergo sum”.

Translated as “I think therefore I am”.

That is proof that I, in some form, exist.

Around 100 years later, Berkeley took this further.

His famous quote was “Esse est percipi”.

Translated as “To be is to be perceived”.

This is the basis of “If a tree falls in the forest and there’s no one there to hear it, is there a noise?”

The answer of course is no.

There may be vibration and molecular movement of the air.

But without an eardrum to experience the movement and a brain to interpret that movement as noise, there can’t be any noise.

And Berkeley took this a stage further.

All we can ever know of the world is what our mind tells us.

We can’t know whether there even is a world outside our mind.

Because we can never step outside our mind.

So our thoughts are all that is actually real, the material world is just speculation, conjecture.

Which lead Berkeley on to:

“It is inconceivable for a material substance to exist independently of the thinking brain that perceives it.”

Around the same time, Dr Samuel Johnson was compiling the first comprehensive English dictionary.

It became the authoritative work for nearly 200 years.

He included all words and terminology in common usage.

Everything that was spoken by, and relevant to, the common man.

Johnson was a practical man.

So he became increasingly frustrated at Berkeley’s theorising.

To Johnson it had no purpose, therefore no meaning, therefore no relevance to ordinary life.

But a colleague asked him how he could possibly refute Berkeley about matter existing outside the mind.

At which point Johnson said “I refute him thus”.

And booted a large muddy stone some distance up the street.

No doubt Johnson’s wasn’t a very erudite argument.

But Johnson is the common man and Berkeley is the academic.

And my worry is that advertising belongs to the common man.

But it’s been taken over by the academic.

By incredibly interesting theories.

All of which can only be understood by university graduates engaged in complicated intellectual puzzles and arcane language.

Interesting, but not very practical.

They may be academically fascinating, but that isn’t the issue.

The real issue is, what does it have to do with the common man?

Because, without that, the common man will just boot it away like Johnson’s stone.