User blog comment:Ygrain/How the ending might make sense/@comment-4406862-20120617004040

"He/it claims that Reapers do what they do to protect organic life, but never explains why they should bother in the first place. "

He does explain how organic life represents chaos and that every 50,000 years they clear old advanced civilizations, leaving the unadvanced ones alone (like he explains they did with the humans the last time the Reapers were here) because the advanced civilizations always end up destroying or conquering newer ones. This way they ensure that new life is able to be created, the cycle of "life" continues, and the Reapers have an inexhaustible supply of organic life, materials and technology with which to replenish their own upon the completion of each cycle.

The explanation given by the Catalyst regarding how Synthetic life will inevitably destroy organic life doesn't make sense, especially considering how the Geth had the opportunity to destroy the Quarians during the Morning War but allowed them to leave because they were unsure of the consequences of destroying an entire race, and the fact that you can get the Quarians and Geth to work together again just a few hours prior to this conversation with the Catalyst! Also, in just the previous cycle the Protheans had their own "Geth problem" in the form of the Metacon wars and they were able to defeat them in their time, so why can't the citadel races of current time defeat our synthetic problem? Either way, civilizations show their ability to realize the threat of their mistake (of making too intelligent synthetics) and their ability to eliminate the threat. The fact that the Reapers had such control over the Geth (from 300 years after the Morning war onwards) and used them to attack the Citadel and organic species seems to me to be a perpetuation of their own argument. Essentially the Reapers are making Synthetic life (Geth) attempt to extinguish Organic life (Citadel species), so the Geth were not out to eliminate the Quarians or any other species until AFTER Harbinger had control over them (promising the Geth their ultimate goal of a Dyson-sphere like object which could house every Geth platform) so I'm not sure how trying to save organic life from synthetic life involves the Reapers controlling the Geth into proving their own argument.

To me the catalyst is just the Reaper's last attempt at Indoctrinating Shepard, providing him with misinformation and arguments which are unfairly influenced by the Reapers themselves.