There must be power.
There has to be" is "the power to think that [there has to be.
If you lack the power that you should have, you don't look for it, you don't find it.
When you look for something you think "should be there," you may or may not find it.
If you don't think, "It must be there," you don't look for it, so of course you can't find it.
Example
It is hard to believe that other people have not encountered such a problem in a widely used programming language that I, as a layman, have encountered. Someone out there must have encountered the same problem, solved it, and published it on the Internet, so let's look for it.
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This page is auto-translated from /nishio/あるはずだ力. If you looks something interesting but the auto-translated English is not good enough to understand it, feel free to let me know at @nishio_en. I'm very happy to spread my thought to non-Japanese readers.