Credit cards have been shown to make us spend more. Ryan Sager argues that this isn't the full story:
Every person’s financial situation and mind works differently. For some people, doing many more of their transactions in cash (or check — you have to have some way to pay bills) would be a huge improvement. If you shop a lot recreationally, for instance, this could slow you down. For some people, just using a debit card could be the answer. For me and other people who like a lot of control and data and feedback…a solution like credit cards plus something like… Mint.com is a good answer.
The key, as in so many things, is a high degree of self knowledge, a willingness to experiment and track results, and the information to understand what biases might be driving your behavior.
The Dish 