Searle claims the brain's causal powers are sufficient for intentionality & wrongly, on this basis, that anything with intentionality must have causal powers equivalent to those of the brain.

Philip Cam, 1990.

Necessary & Sufficient Conditions

Necessary and sufficient conditions are different kinds of conditions on an event (called the conditional event) that takes place. In the Chinese room argument the conditional event in question is intentionality (or understanding, or semantics, or meaning), and the question is whether various other events (brain processes, computer program, etc) are necessary or sufficient conditions or both for intentionality. In the example below, the conditional event is a window breaking.

Sufficient Condition
A condition whose presence ensures the occurrence of the event. A throw rock or a gun blast are each sufficient to break the window. There are many possible sufficient conditions of the occurrence of the event (dropping the window, punching it, blasting it with a laser beam, etc).

Necessary Condition
A condition that must be present for the event to occur. For instance, the window will only be broken by events that have enough force in relation to the thickness (strength) of the window. All necessary conditions are required in order for the window to be broken.

Note: The example of the breaking window is of an empirical nature, so the conditions discussed do not hold with absolute logical force. Such conditions are sometimes intended to have stronger force, for example, in logic or maths. The window example is used because it is illustrative.