Answers:

Pat Buchanan:
To steal a job from a decent, hard-working American.

Machiavelli:
The point is that the chicken crossed the road. Who cares why? The ends of crossing the road justify whatever motive there was.

Thomas de Torquemada:
Give me ten minutes with the chicken and I'll find out.

Timothy Leary:
Because that's the only kind of trip the Establishment would let it take

Carl Jung:
The confluence of events in the cultural gestalt necessitated that individual chickens cross roads. This brought such occurrences into being.

John Locke:
Because he was exercising his natural right to liberty.

Albert Camus:
It doesn't matter; the chicken's actions have no meaning except to him.

The Bible:
And God came down from the heavens, and He said unto the chicken, “Thou shalt cross the road.” And the Chicken crossed the road, and there was much rejoicing.

Randy Weaver:
It was a government conspiracy.

Freud:
The fact that you thought that the chicken crossed the road reveals your underlying sexual insecurity.

Darwin:
Chickens, over great periods of time, have been naturally selected in such a way that they are now genetically predisposed to cross roads

Darwin #2:
It was the logical next step after coming down from the trees.

Richard M. Nixon:
The chicken did not cross the road.
I repeat, the chicken did not cross the road.

Oliver Stone:
The question is not “Why did the chicken cross the road?” but is rather “Who was crossing the road at the same time whom we overlooked in our haste to observe the chicken crossing?”

Jerry Seinfeld:
Why does anyone cross a road? I mean, why doesn't anyone ever think to ask, “What the heck was this chicken doing walking around all over the place anyway?”

The Pope:
That is only for God to know.

Louis Farrakhan:
The road, you will see, represents the black man. The chicken crossed the “black man” in order to trample him and keep him down.

Martin Luther King, Jr.:
I envision a world where all chickens will be free to cross roads without having their motives called into question.

Immanuel Kant:
The chicken, being an autonomous being, chose to cross the road of his own free will.

Grandpa:
In my day, we didn't ask why the chicken crossed the road. Someone told us that the chicken had crossed the road, and that was good enough for us.

Dirk Gently (Holistic Detective):
I'm not exactly sure why, but right now I've got a horse in my bathroom.

Bill Gates:
I have just released the new Chicken 2000, which will both cross roads AND balance your checkbook, though when it divides 3 by 2 it gets 1.4999999999.

M.C.Escher:
That depends on which plane of reality the chicken was on at the time.

George Orwell:
Because the government had fooled him into thinking that he was crossing the road of his own free will, when he was really only serving their interests.

Colonel Sanders:
I missed one?

Plato:
For the greater good.

Aristotle:
To actualize its potential.

Karl Marx:
It was a historical inevitability.

Nietzsche:
Because if you gaze too long across the Road, the Road gazes also across you.

B.F. Skinner:
Because the external influences, which had pervaded its sensorium from birth, had caused it to develop in such a fashion that it would tend to cross roads, even while believing these actions to be of its own freewill.

Jean-Paul Sartre:
In order to act in good faith and be true to itself, the chicken found it necessary to cross the road.

Albert Einstein:
Whether the chicken crossed the road or the road crossed the chicken depends upon your frame of reference.

Pyrrho the Skeptic:
What road?

The Sphinx:
You tell me.

Buddha:
If you ask this question, you deny your own chicken nature.

Emily Dickenson:
Because it could not stop for death.

Ralph Waldo Emerson:
It didn't cross the road; it transcended it.

Ernest Hemingway:
To die. In the rain.

Saddam Hussein:
This was an unprovoked act of rebellion and we were quite justified in dropping 50 tons of nerve gas on it.

Saddam Hussein #2:
It is the Mother of all Chickens.

Joseph Stalin:
I don't care. Catch it. I need its eggs to make my omelette.

Dr. Seuss:
Did the chicken cross the road?
Did he cross it with a toad?
Yes the chicken crossed the road,
but why he crossed, I've not been told!

O.J.:
It didn't. I was playing golf with it at the time.