Epicuris: I come hither, O ye Athenians, to justify in your assembly what I maintained in my school, and I find myself impeached by furious antagonists instead of reasoning with calm and dispassionate inquirers.
By my accusers it is acknowledged that the chief or sole argument for a divine existence (which I never questioned) is derived from the order of nature; where there appear such marks of intelligence and design that you think it extravagant to assign for its cause either chance or the blind and unguided force of matter. You allow that this is an argument drawn from effects to causes. From the order of the work you infer that there must have been project and forethought in the workman. If you cannot make out this point, you allow that your conclusion fails, and you pretend not to establish the conclusion in a greater latitude than the phenomena of nature will justify. These are your concessions. I desire you to mark the consequences.
When we infer any particular cause from an effect we must proportion the one to the other, and can never be allowed to ascribe to the cause any qualities but what are sufficient to produce the effect. A body of ten ounces raised in a scale may serve as a proof that the counterbalancing weight exceeds ten ounces, but never that it exceeds a hundred.
The same rule holds whether the cause assigned be brute, unconscious matter or a rational, intelligent being. If the cause be known only by the effect, we never ought to ascribe to it any qualities beyond what are precisely requisite to produce the effect. Nor can we return back from the cause and infer other effects from it beyond those by which alone it is known to us.
Allowing, therefore, the gods to be the authors of the existence, or order, of the universe, it follows that they possess that precise degree of power, intelligence, and benevolence which appears in their workmanship; but we can never be allowed to mount up from the universe, the effect, to Jupiter, the cause, and then descend downwards to infer any new effect from that cause. The knowledge of the cause being derived solely from the effect, they must be exactly adjusted to each other; and the one can never refer to anything farther.
I deny a Providence, you say, and Supreme Governor of the world, who guides the course of events and punishes the vicious with infamy and disappointment, and rewards the virtuous with honour and success in all their undertakings. But surely I deny not the course of events itself, which lies open to everyone's inquiry and examination. I acknowledge that, in the present order of things, virtue is attended with more peace of mind than vice, and meets with a more favourable reception from the world. I am sensible that, according to the past experience of mankind, friendship is the chief joy of human life, and moderation the only source of tranquillity and happiness. I never balance between the virtuous and the vicious life, but am sensible that, to a well-disposed mind, every advantage is on the side of the former. And what can you say more, allowing all your suppositions and reasonings?