Different types of Consideration that are not real are:
Though consideration need not be adequate, it must be of some value in the eye of law, i.e., it must be real and competent. Where consideration is physically impossible, illegal, uncertain or illusory, it is not real and therefore shall not be a valid consideration.
(i) Physically impossible:
ADVERTISEMENTS:
A promise to do something which is physically impossible, e.g., to make a dead man alive or to run at a speed of 100 kilometres per hour, does not form valid consideration.
(ii) Legally impossible:
A promise to do something which is illegal, e.g., a promise for illegal cohabitation, does not amount to good consideration.
ADVERTISEMENTS:
(iii) Uncertain consideration:
A promise to do something which is too vague and uncertain, e.g., a promise to pay such remuneration “as shall be deemed right,” is no consideration in the eye of law.
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(iv) Illusory consideration:
Again, an illusory or deceptive consideration does not amount to a valid consideration. Consideration is illusory if it consists in a promise to perform a public duty, or to perform a contract already made with the promisor.