Abstract explanation: State the apriori probability of the hypothesis/question. This is your "gut feeling" about the hypothesis before considering any evidence. Let's say you think the apriori probability is 0%. That means you, regardless of the evidence, believe the hypothesis is impossible. Or, if you specify 100%, you believe the hypothesis is certain to be true, regardless of the evidence. These are the two extremes that must be avoided if one considers oneself open to evidence! You can specify any value, but ChatGPT says 5% means 'very skeptical' and consequently 95% means 'very confident'. The default is 50%, which means you are neutral and have no prior bias about the hypothesis.

Example: After entering the apriori probability, you can add evidence. Let's assume an example hypothesis: "Unicorns exist". We can then think of an evidence such as "I found a long straight & twisted horn". We must now specify two probabilities: 1) The probability of this evidence if the hypothesis is true, and 2) the probability of this evidence if the hypothesis is false. You do this by imagining that the hypotheis is true and then ask yourself: "Unicorns exist, then how likely is it that I would find such a horn?" and then you do the same for the case where the hypothesis is false: "Unicorns do not exist, then how likely is it that I would find such a horn?" Let's try it out:

• P(E_i | H): The probability of the evidence if unicorn exists. We can say that the probability of such a horn is 80%, since we don't know if unicorns tends to lose their horns.
• P(E_i | ¬H): The probability of the evidence if unicorns do not exist. We can say that the probability of such a horn is 79%, since it is likely that such a horn could be found in nature (from a narwhal perhaps?) or maybe it's fake?

Once you have entered the apriori/initial probability and at least one piece of evidence, the result will be calculated. The result will update as you add or change evidence. The result is probability of the hypothesis given the all evidence. In our example, if we choose 1% as the apriori probability, and the two probabilities above, the result will be 1,01% - a slight increase in the probability. Test some values below, and see the result yourself!