Buddhism is a tradition that has developed for 2,500 years, and it is tremendously complex and rich. Obviously, we can't tell you every detail of Buddhist philosophy. This is just a practical introduction to some important concepts of Buddhist philosophy and what they mean in daily life.
Although faith is important, Buddhism does not insist on blind faith. Instead, Buddhists are encouraged to examine teachings intellectually and experientially. Of course, some things that Buddhism teaches can't be known through direct experience or logic, at least for ordinary beings. But they can be known through the enlightened experience of Buddha. Until we reach that levels ourselves, we have to take it on faith -- but we can use reason to see if the teachings are at least logically consistent and reasonable in principle, and if the teachers seem trustworthy and spiritually mature. We can and must apply the teachings in practice, develop our own spiritual vision, and verify the teachings in our own experience.
THE GROUND: Buddha Nature. Buddhist philosophy starts from the recognition that the fundamental nature of the mind of all sentient beings is awareness, openness, and limitless freedom. This inherent nature of the mind is called Buddha Nature, and it is present equally in all beings, regardless of age, gender, race, etc.
However, this fundamentally pure nature of the mind, though present in all beings, is obscured by the negative emotions, concepts, and habits that ordinary beings are constantly engaged in. In other words, caught up in the thoughts and emotions of ordinary life, we become confused about our true nature.
In particular, the fundamental negative emotions that obscure our enlightened nature are
known as the "Three Poisons". In Sanskrit, they are known as the kleshas. There are other kleshas, such as pride and jealousy, but they all arise from these three fundamental roots. In brief, we can sum up the problems that veil our enlightened nature as self-centeredness or "ego" (although this means something different for Buddhists than it does for psychologists).
Based on these negative emotions, we engage in actions (karma) of body, speech, and mind that give rise to suffering in our lives, just as planting a seed gives rise to fruit in the future. It is important to understand that in Buddhism, suffering is not seen as "punishment" for bad deeds, but simply a natural process of cause and effect. Deeds based on attachment, aggression and ignorance naturally give rise to suffering, while deeds based on a mind of non-attachment, non-aggression, and wisdom naturally bring happiness into our lives.
In Buddhism, this process continues from one life to the next, through the process of Rebirth. Though the body ceases to exist at death, the mind continues into a future existence, and carries the seeds of karma into the next life. Different conflicting emotions lead to rebirth in different realms, some of which are not visible to humans, though others are.
Hell realms - anger
Hungry ghost - greed
Animal - ignorance
Human - passion
Demi-god - jealousy
God - pride
This process of rebirth happens with little or no freedom of choice for most of us. Ordinarily, we have no more control over our rebirth than we do over our dreams. However, through spiritual practice, it is possible to obtain control over this process and direct your rebirths towards your continual spiritual growth.
Learn More: See Chogyam Trungpa, Cutting Through Spiritual Materialism and Khenpo Karthar, Dharma Paths for a discussion of the Six Realms. Sogyal Rinpoche discusses Buddha Nature and the process of death and rebirth in The Tibetan Book of Living and Dying. A traditional discussion of these basic teachings is found in Gampopa's Jewel Ornament of Liberation (translated by Khenpo Konchog Gyaltsen).
THE PATH: Overcoming Confusion. We need to recognize that although the nature of our minds is obscured by confusion, it is not harmed by that confusion -- just as a mirror may reflect all kinds of negative things but is not itself harmed by the reflections. So we don't need to feel bad about ourselves. In fact, all we have to do is relax and slowly penetrate the negativity that obscures our enlightened nature, and our own Buddha-qualities will naturally shine out more and more. All Buddhist practice is about unveiling the enlightened qualities that are inherent in the nature of our minds.
The confusion that veils our Buddha Nature is based on "ignorance" (marigpa). Ignorance is a fundamental misunderstanding and misperception of ourselves and our world. We are continually projecting our own preconceived ideas and concepts onto our experience, which blocks us from experiencing things the way they actually are. This confusion gives rise to all of our negative emotions and karma.
"How things really are" is described in Buddhist philosophy as Emptiness (shunyata). Emptiness is often MIS-understood in the West to mean "nothingness", as if to say that nothing exists. This extreme view is known as "nihilism", and it is a great obstacle to Buddhist practice. If you cling to the idea that nothing exists, then you may behave in ways that only solidify your own ego and cause harm to yourself and others.
On the other hand, emptiness DOES mean that things don't exist the way we think they do. Things seem real and solid and permanent to us, but when we analyze closely, we see that everything is impermanent and constantly changing. In other words, they are "empty" of our confused projections. Recognizing this not just intellectually but experientially removes our ignorance and confusion, and creates a tremendous sense of space in our lives. An example that is traditionally given is that of a person who mistakes a coiled rope for a snake, and experiences tremendous fear and suffering because of that. However, through investigation, the person realizes that it is just a rope, and that there was never a snake there in the first place -- and the fear and suffering vanishes. It was based on illusion.
Through studying Buddhist philosophy, and developing helpful and correct concepts about the world by contemplating the teachings, our spiritual practice can develop more powerfully. Eventually though, we need to move beyond a merely conceptual understanding and develop direct experience through meditation. This 3-step process is how we grow in wisdom.
All Buddhist traditions emphasize a combination of meditation practice and study. It is said that study without meditation is like having eyes, but no legs -- you can see where you want to go, but you can't get there. On the other hand, meditation without some study is like having legs, but no eyes -- you are walking, but you have know idea if you are headed in the right direction or not.
Learn More: Lama Surya Das discusses many aspects of Buddhist practice in Awakening the Buddha Within. The Dalai Lama has an excellent discussion of emptiness and interdependence in The Meaning of Life from a Buddhist Perspective. Khenpo Tsultrim Gyamtso discusses the philosophy of emptiness in The Progressive Stages of Meditation on Emptiness. See also the discussion of the Buddhist path in The Jewel Ornament of Liberation, especially the chapter on "Wisdom".
THE FRUIT: Enlightenment. The result of Buddhist practice is to unveil the Buddha Nature within us, so that all its enlightened qualities of wisdom, compassion and power can shine without distortion. One way of describing the qualities of enlightenment is as the Three Bodies of the Buddha.
1) Dharmakaya. The "Wisdom Body" of the Buddha is the fundamental nature of the mind as openness, space and awareness. This enlightened awareness, though it has no form in itself, manifests as two "Form Bodies" in order to benefit other beings. These enlightened manifestations happen spontaneously without thought or effort, due to the compassion of the Buddhas.
2) Sambhogakaya. The "Enjoyment Body" represents forms of color and light that are perceived in meditation, and that give teachings and blessings to advanced meditators. Many of the deity practices of Tibetan Buddhism consist of visualizing these pure forms of enlightenment.
3) Nirmanakaya. The "Emanation Body" is the form perceptible by ordinary beings who have the good karma to come into contact withan enlightened being. The most famous example of a nirmanakaya is Shakyamuni Buddha, who lived and taught in India 2,500 years ago. However, other highly realized beings also take rebirth in ordinary form in order to teach and lead other beings towards enlightenment. The Tibetan word for such beings is Tulku.
However, let's remember that the qualities of enlightenment are our inherent potential already. We don't have to struggle to be something we are not, but instead, we can relax and become more and more who we genuinely are, beyond all the confusion and negativity that dominate our lives. It's like the sun, which may temporarily be obscured by clouds, but it's still shining -- even if only a little light is getting through. Through meditation and study we dissolve the clouds, which become thinner and thinner, and let more and more light shine, until one day our true Buddha Nature shines forth without any veil. That is called enlightenment.