The strongest arguments for and against raising the blocksize are all about decentralization. For the raise: As the number of transactions organically grows, i

The strongest arguments for and against raising the blocksize are all about decentralization. For the raise: As the number of transactions organically grows, if the blocks fill up, users will be pushed to "off-chain" services such as CoinBase or ChangeTip. This will hurt decentralization, because these services are basically banks. Against the raise: As the size of blocks have grown, the number of full nodes has fallen. Further increases in block size will only make the number of full nodes decrease further (because of increased requirements for bandwidth, memory, and disk space), which will hurt decentralization.