It's a shame nobody ever thought to ask this question in the past. Then we wouldn't have to try and figure out such a complicated concept today.

Just for fun, lets see what a quick Google search turns up?

Quote from: DeathAndTaxes on November 28, 2013, 04:49:28 PM

Nodes (once again ALL NODE not just miners) use the longest (most work) VALID chain.

Quote from: CIYAM on February 11, 2014, 04:50:18 PM

Quote from: ChuckOne on February 11, 2014, 04:36:45 PM

But then, what's the legitimate branch of the chain?

That is determined by what in Bitcoin terms would be "the most work".
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Quote from: gmaxwell on May 05, 2014, 11:52:37 PM

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This attack does not exist because Bitcoin chooses the chain with the most work, not the most blocks.

Quote from: BoardGameCoin on July 27, 2012, 10:47:03 PM

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bitcoin uses a cryptographic proof of work with a most-work-wins approach to double-spend resolution.
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Quote from: DeathAndTaxes on January 01, 2014, 10:35:53 PM

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* Longest technically means the most work not necessarily the most blocks as Bitcoin selects as the primary chain the one with the highest collective difficulty.

Quote from: dree12 on April 15, 2013, 12:40:18 AM

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The Bitcoin client will accept the "longest chain", which is the chain with the most work behind it.
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Quote from: maaku on May 15, 2013, 06:58:08 PM

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Client trusts the longest (most work) chain,
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Quote from: CJYP on August 22, 2014, 04:19:55 PM

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The bitcoin protocol specifies that in the case of a blockchain fork the winning chain is the one with the most work in it.
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Wow. It's almost like there's an actual reason that the system is called "proof-of-work". As if it's necessary to somehow provide cryptographic proof that your chain involved the most work in order to be considered to be the current consensus chain.