Rationality Quotes Thread August 2015

Another month, another rationality quotes thread. The rules are:

Please post all quotes separately, so that they can be upvoted or downvoted separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote from Less Wrong itself, HPMoR, Eliezer Yudkowsky, or Robin Hanson. If you'd like to revive an old quote from one of those sources, please do so here.
No more than 5 quotes per person per monthly thread, please.
Provide sufficient information (URL, title, date, page number, etc.) to enable a reader to find the place where you read the quote, or its original source if available. Do not quote with only a name.

Another month, another rationality quotes thread. The rules are:

Please post all quotes separately, so that they can be upvoted or downvoted separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote from Less Wrong itself, HPMoR, Eliezer Yudkowsky, or Robin Hanson. If you'd like to revive an old quote from one of those sources, please do so here.
No more than 5 quotes per person per monthly thread, please.
Provide sufficient information (URL, title, date, page number, etc.) to enable a reader to find the place where you read the quote, or its original source if available. Do not quote with only a name.

Context (Hacker is Britain's Prime Minister, Sir Humphrey is his chief subordinate, the Russians are their enemy in the Cold War)

Double Context: This quote is from "Yes Prime Minister", a british comedy show.

Sir Humphrey: Bernard, what is the purpose of our defence policy?

Bernard: To defend Britain.

Sir Humphrey: No, Bernard. It is to make people believe Britain is defended.

Bernard: The Russians?

Sir Humphrey: Not the Russians, the British! The Russians know it's not.

How about adding the source?

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