The answer is: we don’t know. The deck of cards can be stacked, the die may be false. And yet, as humans, we tend to believe that we’re pretty good at both seeing randomness and generating it.
Looking at it psychologically there are three main parts of randomness: that events aren’t dependent, that events are consistently likely (meaning that their chance doesn’t change much over time) and that the outcomes match what we believe about the system.
For example, we believe that die rolls are random. But if we roll ten sixes in a row we tend to believe that we shouldn’t roll another one (the Gambler’s Fallacy), that it’s “time” for a different result. But if we are told that the system has been rigged we’ll tend to believe that those sixes are a result of that rigging, even if we don’t know what that rigging consists of or whether it exists at all.
That’s because we’ve trained ourselves to think in certain terms. Dice are random. Cards are random. But cards feel slightly less random than dice. Ask someone to select an image of a random thing and in 99% of the cases they will choose a die.
We’re trained to consider dice random from a very early age. Most people play die rolling games, like Snakes and Ladders, Parcheesi or Monopoly, at an early age. The idea of generating random numbers from dice becomes ingrained in our psyche.
But imagine poor Viking tribesman from around Ceasar’s time. They wouldn’t have had dice (dice would have been exclusive to them, if they used them at all) and may have drawn lots instead using pieces of straw. Would they have imagined straw as an image of randomness? Maybe. Possibly. My point is that the feeling of something being random is just that, a feeling.
Randomness is a complex matter. On one side we’ve got mathematical randomness, the probability of events to occur. On the other hand we’ve got the feeling of randomness, that some things are beyond our control. And while mathematical randomness is inviolate, the feeling of something being random is not.
Which brings us back to my original question: why do some things feel more random than others?
Easy answer: mental (and cultural) bias. It might be just as random to roll a die as it is to draw a chit from a cup but on casual examination the drawing of the chit feels less random (yes, I am aware that there’s great variance in this). My personal theory is that the action of pulling something makes people feel that they’re actively choosing, as opposed to waiting for the result of the thrown die. Add to this the common “dice are random” mental image and we get a spread of randomness amongst equally good randomizers.
This is something that we can use in designing our games. When we’re looking for a feeling of randomness we can use dice. When we’re looking for a feeling of action, possibly even control, we can use cards, chits or something that doesn’t have quite as strong mental ties to randomness. We can increase a certain feeling in our designs by leveraging common biases.