ABSTRACT
In some sense, thought is subject to certain fundamental conditions is obvious. Hence attempts have been made to formulate the fundamental laws that are necessarily involved in all thought. The laws that are most commonly stated are those of Identity, Contradiction, Excluded Middle and Sufficient Reason. Any statement that would be definitely rejected as untrue by many of the leading writers on philosophical subjects could scarcely be described as a necessary Law of Thought. In what is commonly called Formal Logic, only one kind of implication is dealt with that involved in the conception of classes. The formal treatment of thought can, however, be extended, as it is in modern mathematical logic, so as to deal with other relations than those of classes. Kant thought, for instance, that, without the Postulates of Freedom, Immortality and God we could not give a satisfactory account of the moral life.
