If you have a fair coin, and then you toss it ten times and it lands ten heads in a row, that result is no longer unlikely -- it has a probability (in whatever

If you have a fair coin, and then you toss it ten times and it lands ten heads in a row, that result is no longer unlikely -- it has a probability (in whatever sense that word is now meaningful) of 100 %. You can only judge hypotheses more or less likely in relation to each other. When you have multiple hypotheses that all explain the current situation, one may be more likely to have happened in the past than another. So if all you know is that on the first 20 tosses half were heads, you might say it's less likely the sequence was ten heads followed by ten tails, than some mix of heads and tails. But of course, the difficult part is judging whether two hypotheses explain the same outcome. That's often somewhat subjective when it comes to historical analyses like these.