A cause is outlined as an unconditional and invariable antecedent of an effect and an effect as an unconditional and invariable consequent of a cause. The same cause produces the same effect; and the same effect is produced by the same cause. The cause is not present in any hidden form whatsoever in its effect.

The conditions mentioned below should be met:

• The cause must be antencedent (Purvavrtti)
• Invariability (Niyatapurvavrtti)
• Unconditionality (Ananyathasiddha)

Nyaya recognises five kinds of accidental antecedents (Anyathasiddha):

• Just an accidental antecedent. E.g., The colour of the potter`s cloth.

• Remote cause is not a cause because it is not unconditional. E.g., The father of the potter.

• The co-effects of a cause are not causally related.

• Eternal substances, or eternal conditions are not unconditional antecedents. e.g. space.

• Unnecessary things, e.g. the donkey of the potter.

Nyaya recognises three kinds of cause:

• Samavayi, material cause. E.g. Thread of a cloth.

• Asamavayi, colour of the thread which gives the colour of the cloth.

• Nimitta, efficient cause, e.g. the weaver of the cloth.