Where does the Bible say that?

Sometimes, when I'm defending the Bible, my opponent will challenge me: "Where's that in the Bible?" Here's a recent example:

Hays

Regarding Gen 7:20, the text doesn't say the waters rose to a depth of 15 cubits above the mountains. The Hebrew text simply says the waters rose 15 cubits above, and the mountains were covered.

So "15 cubits above" may well have reference to ground level, which was sufficient to wash over the surrounding hillside. Think of a flood plain or river basin skirted by hills. Keep in mind that "mountain" isn't a technical term in Hebrew, but a synonym for "hill".

Kenton

Okay, if I accept that dubious definition then how come there weren’t survivors? Surely people could have headed toward higher ground that wasn’t covered or, more importantly, use their own boats? Pretty sure boats were a common thing back then.

Hays

Heading for higher ground may save you from drowning, but with contaminated drinking water, how long will you survive?

Kenton

I missed that part of the Bible. Which verse was that in? 

Hays

The account doesn't say they all died by drowning. It just says they all died in the flood. You do realize, do you not, that there's more than one way people may die as a result of flooding? Having a boat might prevent you from drowning, but it doesn't prevent you from death by starvation, exposure, or cholera.

1. Kenton's objection represents a misunderstanding of sola scriptura. When we interpret the Bible, we combine what the Bible says with extrabiblical background knowledge. To take a comparison, if I read a news report about a passenger plane crashing, I can mentally fill out certain details not included in the report. Indeed, the reporter expects me to know what airplanes are. 

At one level, my knowledge of the event is dependent on the report. Absent the report, I wouldn't know that a passenger plane crashed on that day in that place. However, I can mentally supplement the report with my general knowledge of airplanes and airplane crashes. 

So there's the direct information supplied by the report. It tells me that a particular kind of event occurred. But over and above the report, the nature of the event in itself is an additional source of information. It would be silly for someone to object: "Where did the report say that?"–if I'm making common sense assumptions or drawing reasonable inferences from the nature of the event. The report doesn't have to say that. Once the report says it happened, then the nature of the event is an implicit source of information, in addition to what the report explicitly mentions. An event of that kind may raise a number of possibilities. More than one possible explanation or reconstruction. 

If the Bible says King David was a man, we can infer certain things from that identification. He had hands and feet, fives senses, and male anatomy. To ask, "Where does the Bible say that?" is confused. For certain things follow from what the Bible says. That's understood. The reader is responsible for filling the gaps. If the Bible says King David was a man, that's both a direct source of information about David as well as an indirect source of information about David. There's what it specifically says. But based on what it says, we justifiable draw further conclusions. And the reader is supposed to do that.

If the Bible says people died in the flood, it needn't specify how, exactly, they died, as if they all had to die the same way. While it's possible that they all died the same way, that's not an implication of death by flooding. Death by drowning is a direct result of death by flooding, but that doesn't rule out death by "complications" caused by flooding. A massive deluge may well generate different causes of death. Some more immediate while others are more drawn out and roundabout. To take modern examples, consider people stranded on the roof of their house, waiting to be rescued. Although they survived death by drowning, that doesn't mean they survived death by flooding. Some of them still perish as they wait in vain to be rescued. 

You needn't agree with that interpretation of the flood account. I'm just using it to illustrate a hermeneutical principle. 

2. Of course, that's a question we frequently press against Catholics: "Where does the Bible say that?" But there's a difference. 

i) We wouldn't object to Catholic dogmas if those were implied by what Scripture does say. The problem with Catholicism isn't simply that they believe things we can't find in the Bible. Rather, they believe things when there's no good evidence anywhere! No good evidence in Scripture. No good evidence outside of Scripture. Indeed, they believe some things that run contrary to extrabiblical evidence (not to mention things contrary to the witness of Scripture). 

ii) In addition, they insist on a duty to believe or firmness of belief that goes beyond what the evidence warrants. Suppose there's some evidence that Peter ministered in Rome. Fine. But they turn that into a dogma. They make that belief obligatory. A sacred duty. Yet our late, spotty, even contradictory records of Peter's stay in Rome might be mistaken. We should be able to make allowance for the possibility of error.