Fundamentalism has spread from its original dictionary definition as adherence to a literal interpretation and acceptance of Scripture to cover a broader range. So we can talk of the fundamentalism which justified the slaughter of tens of thousands of Christians by other Christians of a different persuasion. Similarly we can talk of Islamic fundamentalists whose understanding of the Koran, the Prophet and the will of Allah leads them to conclusions which are repudiated by many of their fellow adherents, and are unacceptable to Christians. When I left school after ten years of Catholic education I maintained the smug fundamentalist certainty that I knew the ultimate truths, and that those who denied them would be condemned for their intransigence. (I speak of several decades ago.)
The common factor in fundamentalism appears to be the acceptance of an authority which is not open to question, and which rules every other consideration. It is the antithesis of autonomy, which is the deadly enemy of fundamentalism. It is only when we take personal responsibility for our choices, including the choice of accepting an external authority, that we counter fundamentalism. Only in making reason our ultimate instrument of judgment can we maintain our dignity as human beings. Exchanging reason for blind obedience is to wound our humanity, made in the image of God. Those who promote blind obedience are the blind leading the blind. And we all know where they end up.
While we most naturally associate fundamentalism with religious beliefs, we often find it elsewhere. I encountered an example in a blog discussion just the other day. In reply to a blog contribution which claimed that “religion demands absolute subservience.” I pointed out that the Catholic Church required me to take responsibility, through my conscience, for my own moral decisions. To which the contributor replied that the fact that I obeyed this principle simply proved how subservient I was.
In fact there is a commonly encountered form of fundamentalism based on scientific faith. It holds that the only kind of evidence which is acceptable is evidence which supports a materialist, cause and effect, Universe. This is likely to arise in any discussion of freewill. Even though the proponent may claim that he has an active moral sense, he finds this compatible with his insistence that there is no such thing as free will. He will cheerfully condemn religions for such perversions as the Inquisition without noticing that, in the absence of free will, blame is hardly appropriate. He is not even aware that his denial of freewill itself has no validity in the absence of freewill.
Is the fundamentalist (left wing, right wing, materialist or superstitious) a specific psychological type? I suspect so. I would argue that a fundamentalist is a fearful person. This is someone who is distressed by uncertainty. His deep need is to hold on to some principle to which he adheres so powerfully that no doubt can slip into the cracks and contaminate his security. But before we condemn such a person we must be sure that we do not ourselves protect the truths we hold, simply because we need them to be true – for the sake of our peace of mind.