Aquinas begins with two principles that are today at the heart of scientific reasoning. He argues that every effect requires a cause, and that nothing in the world is the cause of its own existence.
You know, I hate Sam Harris. A good friend recommended I read The End of Faith, I did, and somehow it seemed as if I read and understood every individual word in the book, I saw that time had elapsed, yet no change whatsoever had taken place. Reading Sam Harris is like chewing ice for dinner. Dawkins I do like, and consider him one of the most important minds of modern times, but the little bits and pieces of The God Delusion I've read have left me unimpressed, because his arguments therein are all completely beside the point. I'll probably do blog posts on both of them assuming that I find the time to read the entirety of TGD (as for Harris's book, we'll see if I have any tables that need propping up).
Still, as much as I dislike Harris and Dawkins's argument, they deserve a better rebuttal than D'Souza's brain vomit. And I say that as a (very heterodox) Christian. In 1748, David Hume published An Enquiry Concerning Human Understanding, which you can read here online for free.
A relevant excerpt from part four:
25. But to convince us that all the laws of nature, and all the
operations of bodies without exception, are known only by
experience, the following reflections may, perhaps, suffice. Were
any object presented to us, and were we required to pronounce
concerning the effect, which will result from it, without consulting
past observation; after what manner, I beseech you, must the mind
proceed in this operation? It must invent or imagine some event, which
it ascribes to the object as its effect; and it is plain that this
invention must be entirely arbitrary. The mind can never possibly find
the effect in the supposed cause, by the most accurate scrutiny and
examination. For the effect is totally different from the cause, and
consequently can never be discovered in it. Motion in the second
billiard-ball is a quite distinct event from motion in the first;
nor is there anything in the one to suggest the smallest hint of the
other. A stone or piece of metal raised into the air, and left without
any support, immediately falls: but to consider the matter a priori,
is there anything we discover in this situation which can beget the
idea of a downward, rather than an upward, or any other motion, in the
stone or metal?
And as the first imagination or invention of a particular effect, in
all natural operations, is arbitrary, where we consult not experience;
so must we also esteem the supposed tie or connexion between the cause
and effect, which binds them together, and renders it impossible
that any other effect could result from the operation of that cause.
When I see, for instance, a billiard-ball moving in a straight line
towards another; even suppose motion in the second ball should by
accident be suggested to me, as the result of their contact or
impulse; may I not conceive, that a hundred different events might
as well follow from that cause? May not both these balls remain at
absolute rest? May not the first ball return in a straight line, or
leap off from the second in any line or direction? All these
suppositions are consistent and conceivable. Why then should we give
the preference to one, which is no more consistent or conceivable than
the rest? All our reasonings a priori will never be able to show us
any foundation for this preference.
In a word, then, every effect is a distinct event from its cause. It
could not, therefore, be discovered in the cause, and the first
invention or conception of it, a priori, must be entirely arbitrary.
And even after it is suggested, the conjunction of it with the cause
must appear equally arbitrary; since there are always many other
effects, which, to reason, must seem fully as consistent and
natural. In vain, therefore, should we pretend to determine any single
event, or infer any cause or effect, without the assistance of
observation and experience.
This was written more than two hundred and fifty years ago, and it's air tight. There is no justification for the Thomist claim that all events need a cause and no effect is self-causing, other than the human brain is hard wired to perceive things that way. There are no holes.
Jump ahead to the 20th Century and what Hume wounded, Mr. Heisenberg finishes off.
Quantum indeterminacy is the assertion that the state of a system does not determine a unique collection of values for all its measurable properties. Indeed in the quantum mechanical formalism, for a given quantum state, each one of these measurable values will be obtained non-deterministically in accordance with a probability distribution which is uniquely determined by the system state. Note that the state is destroyed by measurement, so when we refer to a collection of values, each measured value in this collection must be obtained using a freshly prepared state.
Cause and effect simply is not an absolute law that the whole universe operates under. If you told any self-respecting physicist every effect requires a cause, and that nothing in the world is its own cause, he'd laugh in your face.
Boom, there we go. Harris and Dawkins's arguments are stupid, because while technically correct they proceed from false premises. D'Souza doesn't even have the "technically correct" part.