Proof Quotes - page 20
Feuerbach is the only one who has a serious, critical attitude to the Hegelian dialectic and who has made genuine discoveries in this field. He is in fact the true conqueror of the old philosophy. The extent of his achievement, and the unpretentious simplicity with which he, Feuerbach, gives it to the world, stand in striking contrast to the opposite attitude (of the others). Feuerbach's great achievement is: (1) The proof that philosophy is nothing else but religion rendered into thought and expounded by thought, i.e., another form and manner of existence of the estrangement of the essence of man; hence equally to be condemned;(2) The establishment of true materialism and of real science, by making the social relationship of "man to man” the basic principle of the theory; (3) His opposing of the negation of the negation, which claims to be the absolute positive, the self-supporting positive, positively based on itself.
Karl Marx
You want to have proven to you that the soul is imperishable and immortal, and you think that the philosopher who is confident in death has but a vain and foolish confidence, if he thinks that he will fare better than one who has led another sort of life, in the world below, unless he can prove this; and you say that the strength and divinity of the soul, and of her existence prior to our becoming men, does not necessarily imply her immortality. ...For any man, who is not devoid of natural feeling, has reason to fear, if he has no knowledge or proof of the soul's immortality. That is what I suppose you to say, Cebes, which I designedly repeat, in order that nothing may escape us...
Socrates
Reason may be employed in two ways to establish a point: firstly, for the purpose of furnishing sufficient proof of some principle, as in natural science, where sufficient proof can be brought to show that the movement of the heavens is always of uniform velocity. Reason is employed in another way, not as furnishing a sufficient proof of a principle, but as confirming an already established principle, by showing the congruity of its results, as in astrology the theory of eccentrics and epicycles is considered as established, because thereby the sensible appearances of the heavenly movements can be explained; not, however, as if this proof were sufficient, forasmuch as some other theory might explain them.
Thomas Aquinas