Idealism

Philosophical idealism is one of the two great historical schools of philosophical thought; and, moreover, it is the one that is completely and totally false! It is false because it imagines that mind and ideas can exist completely separate from and unrelated to the activity of physical brains (or their computer equivalents). The opposite great school of philosophical thought has generally been known as MATERIALISM, and is the most fundamental assumption of the scientific world view. Idealism has been much more popular among those ignorant of, or opposed to, science—especially those under the spell of religion. So much so, in fact, that any adherence to philosophical idealism is the surest indicator that a person has not yet truly escaped the hold of religion.

Many of the most famous philosophers have been idealists of one sort or another, with two of the most notorious being PLATO and BISHOP BERKELEY . Let's begin here with a limerick poking fun at philosophical idealism of the Berkeley sort, which absurdly proclaimed that physical reality (including trees, rocks, houses and people) is only the figment of our mental imaginations:

There once was a man who said: "God
Must think it exceedingly odd
    If He finds that this tree
    Continues to be,
When there's no-one about in the Quad."
    —Ronald Knox

Then a religious reply to the above:

Dear Sir, Your astonishment's odd:
I am always about in the Quad.
    And that's why the tree
    Will continue to be,
Since observed by Yours faithfully, God.
    —Anonymous

Next we compare the idealist philosophy of Berkeley with the more wishy-washy philosophy of Descartes. (A "toper", for those unacquainted with the Queen's English, is one who drinks excessively.)

A toper who spies in the distance,
Striped tigers, will get some assistance
    From reading Descartes,
    Who holds that it's part
Of his duty to doubt their existence.

But if he's a student of Berkeley,
One thing will emerge, rather starkly,
    That he ought to believe
    What his senses perceive,
No matter how dimly or darkly.
    —Leslie Johnson

But if physical objects are not the true reality (according to Berkeley) but only "mental perceptions", then why should we believe "what our senses perceive"? The answer, says Berkeley, is that "esse est percipi" or, in other words, that what it "means" for something to exist is that it is perceived by our minds. This is a good example of the ability of idealist philosophers to cook up rationalizations for their absurd theories!