FAITH... WITH REASON

I doubt anyone would claim certainty that the bridge would hold them. Whether they choose to cross or not doesn't depend on certainty, though, it depends on whether they think the risk is worth the reward. Same thing with my coin flip example but without any solid math. Seeing 5 people safely cross is evidence that it's safe, but whether it's safe enough that will entirely depend on how much value you put on crossing VS how much of a risk you think crossing is. Still, to repeat the central point: crossing doesn't depend on you being certain the bridge is safe. The only way you're putting "faith" in its safety is if you tell yourself there's no risk involved and the bridge is completely safe.