The Buddha taught that there are seven factors that support awakening, or enlightenment. The second of these is, in Pali, dhamma vicaya. Vicaya refers to examination, analysis or investigation; dhamma is the Pali for dharma. In Buddhism, the word "dharma" most often refers to the teaching of the Buddha, but it can also refer to the nature of existence (see "What Is Dharma in Buddhism?").
Notice that it says "investigation of," not "belief in." It cannot be stressed enough that the Buddhist path is not about adopting a belief system or accepting religious authority without question. One of the most frequently quoted passages of all Buddhist scriptures is the Buddha's advice from the Kalama Sutta -- " ... don't go by reports, by legends, by traditions, by scripture, by logical conjecture, by inference, by analogies, by agreement through pondering views, by probability, or by the thought, 'This contemplative is our teacher.'" Instead, judge for yourself what is true.
However, if you read the entire sutta you see that the Buddha provided rigorous criteria for making spiritual judgments. The Kalama Sutta is called a "charter of free inquiry," not "a permission slip to believe whatever you like."
Why Believing in a Doctrine of Enlightenment Is not Enlightenment
Buddhism is built upon the proposition that the way we perceive ourselves and everything else is an illusion, and waking up to reality requires discipline and determination.
The Buddha taught that because enlightenment is different from our conventional experience and and outside our usual points of reference, it cannot be imagined or "figured out." It is perceived only by one's direct, intimately experienced insight. The Buddha himself could not give enlightenment to someone else merely by describing what it is. For this reason, the Buddha did not leave us with a belief system but with a path of disciplined practice.
Working With Buddhist Doctrines
So there you are, walking the path, and before long you bump into one doctrine after another. You're told about the Three Poisons, the Four Truths, the Five Aggregates, the Six Perfections, the Seven Factors, the Eightfold Path, and on and on. And you might wonder, If I'm not supposed to accept these as beliefs, what do I do with them?
And the answer is, investigate them. But how? Many people stumble on this point. Either they accept the teachings as beliefs -- which isn't terribly useful -- or they try to figure them out intellectually, which also isn't terribly useful.
We humans usually learn new things by a process that draws on what we already know. As we listen or read or watch, consciously or unconsciously we classify the new thing according to our existing taxonomy of knowledge. Most of the time this is a reasonably useful learning strategy. But if the new thing is utterly unlike anything we already know, this strategy gets in the way.
Often, if something doesn't immediately "make sense" -- meaning that it doesn't correspond to anything we already know -- we are likely to reject it pretty quickly. Or, we "interpret" the new thing so that it does fit into what we already know. However, to do that we have to distort the new thing to make it fit, meaning we aren't seeing it as it is, but as we think it's supposed to be.
Much of Buddhist practice amounts to opening ourselves up to new ways of understanding. In particular the practices of mindfulness and concentration quiet our minds so that we stop judging and comparing and classifying.
Thich Nhat Hanh said,
"We need to empty our mind, and be free of thoughts, ideas, and perceptions in order to listen to a Dharma Talk (Buddhist teaching). Comparing what we hear with something we already had in mind, and drawing "right" or "wrong" conclusions is a mental habit that limits our capacity of listening. To agree or disagree with what is said does not help us learn anything new. To listen deeply, we do not engage our intellect while listening."
To "not engage our intellect while listening" does not mean blind acceptance. It just means staying open. A teaching that baffles you the first time you hear it may open the door to realization the third or fourth of tenth time you hear it.
Over the centuries the several schools of Buddhism have developed many different approaches to dharma. Some of these approaches may seem "out there" -- Tibetan tantra, Zen koans. Others are more analytical. Most schools combine some amount of "book learning" with meditation or some other concentrated practice to transform consciousness. Most schools also recommend working personally with a dharma teacher who can guide you beyond the boundaries of your particular projected reality.
So, exactly how you investigate the dharma depends on the school in which you choose to practice. And it may take some time to get the hang of it. But the Theravadin teacher Piyadassi Thera (1914-1998) said,
"One who goes in quest of truth is never satisfied with surface knowledge. He wants to delve deep and see what is beneath. That is the sort of search encouraged in Buddhism."