I don't know about 'strictly a matter of faith'. There is some pretty good evidence that 100% taxation (i.e. 100% of your earnings belong to the state and not to you) doesn't work to well.
I'm not suggesting that there aren't reasonable arguments about what the marginal tax rate curve should look like (flat, curved, etc.) to optimize various economic metrics--just that there are some configurations that we can rule out as unworkable without much real controversy.
I'm not suggesting that there aren't reasonable arguments about what the marginal tax rate curve should look like (flat, curved, etc.) to optimize various economic metrics--just that there are some configurations that we can rule out as unworkable without much real controversy.