From Rigpa Wiki
Doubt (Skt. vicikitsā; Tib. ཐེ་ཚོམ་, tétsom; Wyl. the tshom) is one of the six root destructive emotions and one of the seven kinds of cognition identified in Buddhist logic and epistemology. As defined in the Abhidharma, it is characterized by uncertainty as regards the truth and acts as the basis for not engaging oneself in virtue.
Sogyal Rinpoche writes:
- I sometimes think that doubt is an even greater block to human evolution than desire and attachment. Our society promotes cleverness instead of wisdom, and celebrates the most superficial, harsh, and least useful aspects of our intelligence. We have become so falsely "sophisticated" and neurotic that we take doubt itself for truth, and the doubt that is nothing more than ego's desperate attempt to defend itself from wisdom is deified as the goal and fruit of true knowledge. This form of mean-spirited doubt is the shabby emperor of samsara, served by a flock of "experts" who teach us not the open-souled and generous doubt that Buddha assured us was necessary for testing and proving the worth of the teachings, but a destructive form of doubt that leaves us nothing to believe in, nothing to hope for, and nothing to live by.
His Holiness the Dalai Lama says: "There are actually three types of doubt: incorrect doubt, uncertain doubt, and correct doubt. The first type involves starting to think about the truth but still doubting it is correct. The second is more open but ambivalent and unsure of what is correct or incorrect. The third is when we start to believe in the truth."
- Sogyal Rinpoche, The Tibetan Book of Living and Dying, revised and updated edition (Harper San Francisco, 2002), 'Doubts on the Path', pages 126-130.