Can Bitcoin's algorithm of 50% majority be adjusted to 95% agreement acceptance?

[cloud9]

Would the Bitcoin blockchain not be more secure if the blockchain acceptance criteria of 50% majority of nodes becomes 95% agreement of nodes at certain stages of high single mining pool node concentration?

See also http://forum.bitcoin.org/index.php?topic=12153.msg170894#msg170894 ?

[Stefan Thomas]

There is no "50% majority algorithm".

Bitcoin considers the longest block chain valid. So requiring anything other than simple majority would mean something like waiting for competing chain forks to reach a significantly different length before accepting either one. This is problematic because a single side chain block can make the main chain untrusted for 20 blocks (using the 95% case as an example).

Another way to put it: Requiring 95% acceptance essentially means that Bitcoin can be shut down with only 5% hashing power (because the rest of the network will no longer be able to achieve a 95% consensus).

[gene]

Would the Bitcoin blockchain not be more secure if the blockchain acceptance criteria of 50% majority of nodes becomes 95% agreement of nodes at certain stages of high single mining pool node concentration?

See also http://forum.bitcoin.org/index.php?topic=12153.msg170894#msg170894 ?

Read up on the byzantine generals' problem.