The necessitarians are all compelled to concede that the universal conviction of our race is, and always has been, that man is free. They have, however, asserted that this dictate of common-sense is not to be accepted as philosophically true. Lord Kames admits the natural conviction of freedom from necessity, though he declares it to be an illusion: "Man fondly dreams that he is free to act; Naught is he but the powerless, worthless plaything Of the blind force that in his will itself Works out for him a dread necessity." And Hommel, certainly one of the ablest and most decided of fatalists, says, "I must believe that I have a feeling of liberty, at the very moment I am writing against liberty, upon grounds which I regard as incontestable. Zeno was a fatalist only in theory; he did not act in conformity with his convictions."[527] The possession of alternative power is a fact of consciousness as clear and indubitable as the fact of personal existence. It is admitted by the necessitarians that all men have "a natural conviction of freedom;" they believe themselves to be free beings, and they act upon this belief in all the relations of life. If this fact of consciousness is an illusion, then our existence is also an illusion, for that same intuition which certifies to me that I exist certifies also that I am free. If the testimony of consciousness is invalidated, there is no criterion for truth. If one of its deliverances is found to be false, how can we vindicate the veracity of any? "Our faculties are bestowed upon us as the instruments of deception; the root of our nature is a lie, and universal skepticism is the only goal." 2. _The idea of moral obligation necessarily presupposes the freedom of the will._ This is a principle so obvious that it needs no elucidation. If man have duties, he must possess the power of fulfilling them. He ought to be free if he ought to obey law, or human nature is in contradiction with itself. The direct certainty of obligation implies the corresponding certainty of freedom. Hence Kant's well-known canon, "_I ought, therefore I can._" Though denying the direct consciousness of freedom, Kant maintained with earnestness that the fact of liberty is guaranteed by the existence of the moral law, whose categorical imperative _thou shalt_ necessarily implies a corresponding _thou canst_. To the same effect are the words of Sir William Hamilton: "The fact that we are free is given to us in the consciousness of an uncompromising law of duty.... Our consciousness of the moral law, which without a moral liberty in man would be a mendacious imperative, gives a decided preponderance to the doctrine of freedom over the doctrine of fate."[528] Physical causation and moral obligation can not coexist side by side. In proportion as we extend the domain of necessity we must diminish that of duty.