The coding system behind Bitcoin makes it impossible to counterfeit
A major reason many people are distrustful of Bitcoin is for fear that since it is entirely online, it could be easily counterfeited.
The block chain is the skeleton of Bitcoin, a digital ledger that regulates and tracks the owner of every Bitcoin and every transaction. The block chain is how Bitcoin can be decentralized unlike a traditional bank. When a transaction occurs or a Bitcoin is mined, the device adds on a digital “block” to the chain, which details the transactions sender, receiver, and amount. Thus, Bitcoin’s information is distributed to those using it, each adding a block onto the chain which tracks the entire Bitcoin economy. If someone were to spend a Bitcoin more than once and counterfeit it, the chain would branch. Two (or more) blocks would be added containing details for the same Bitcoin, so the blocks would exist side by side as two branches in the block chain. The block chain and the computers running Bitcoin protect against this. In instances of branching, Bitcoin accepts the branch which has spent the longest time as part of the block chain. The “real” (or first) transaction would have the entire block chain attached to it, while the second would be a brand new one. The longer branch would be accepted, and the software would treat the counterfeit as if it had never occurred. The only theoretical way for a Bitcoin to be counterfeited would be for another branch to surpass the length of the original. However, this would require a counterfeiter to control a large majority of the CPU power of the entire Bitcoin network, meaning one user would have to have a power equal to millions of computers. This is practically impossible.
It is likely somebody will figure out how to counterfeit Bitcoin. Despite numerous government protections, people have figured out how to counterfeit government-backed currencies, including national bank notes and Federal Reserve notes, so they will be able to figure out a way to counterfeit Bitcoin too.
[P1] Bitcoin relies on blockchain technology. [P2] Blockchain technology makes counterfeiting impossible. [P3] Counterfeiting Bitcoin is impossible.
Rejecting the premises
[Rejecting P1] Blockchain technology is not foolproof. [Rejecting P2] Blockchain technology makes counterfeiting incredibly difficult, but no system is impossible to hack. [Rejecting P3] Many secure types of currencies have been counterfeited before. Therefore, Bitcoin will eventually be able to be counterfeited as well.