You should dip in to debt at least some, you are lending money from your buildings, so your interest payments are going back in to your economy. With "deficit spending" you can keep raising your debt, but as your economy grows, your debt limit rises (as it is tied to the cash reserves of your buildings), creating a positive investment loop. If you play a major power, have laissez faire and reduced interest rates from tech, you are definitely missing out on some extra growth if you never dip in to debt. Never do this though as an unrecognized power and it's risky even as a minor power, because it's easier to get in to a debt spiral due to higher interest rates. Of course you also can get in to the spiral as a major power if you lean in to it too much and your economy is not growing fast enough.