Disproving Odin - An Experiment in arguing with a theist with Theist logic

[Jenny A]

I remember no such thing.  And I'm going to start here, because I find this statement flabergasting.   

We are rehashing things already discussed. I cannot possibly know what posts you have read. Here is the very first paragraph under the article of Inductive Reasoning:

Inductive reasoning (as opposed to deductive reasoning or abductive reasoning) is a method of reasoning in which the premises are viewed as supplying strong evidence for the truth of the conclusion. While the conclusion of a deductive argument is certain, the truth of the conclusion of an inductive argument may be probable, based upon the evidence given.[1] https://en.wikipedia.org/wiki/Inductive_reasoning

More likely than not is not the standard for premises in syllogisms.   (I'll get to whether your premises exceed that standard in minute). If your standard is, "more likely than not," then you are obliged to add more likely than not to each conclusion following from that premise.  If more than one of your premises is merely "more likely than not" the chances of  the conclusion following from those premises will fall below 50%.  For example, if the chance premise A is correct is 51% and the chance premise B is correct is also 51%, then the chances that they are both correct is just 26%. Even if the chances that each premise is correct are 70% the chances of both premises being correct drops to 49% and thus becomes less likely than not.

Just about everything in that paragraph is wrong--starting with your requirements about premises in a syllogism. Read the link above to learn more about an inductive argument. 

As to the percentage question, you do NOT multiply probabilities together to come up with a net probability in a syllogism. The conclusion's probability is equal to the lowest of the premise probabilities. Think about it--the more premises you have that are likely true would reduce the net probability if you multiplied them together. 

The proposition you have stated is:

All things that begin to exist have a cause
The universe began to exist
Therefore the universe had a cause

That is a syllogism.  Syllogisms use deductive reasoning from two or more propositions to reach a conclusion.  If the logic is sound, and all of the propositions are true, the the conclusion follows.  If any proposition is false the  syllogism  fails.  https://en.m.wikipedia.org/wiki/Syllogism  https://www.merriam-webster.com/dictionary/syllogism  http://philosophyterms.com/syllogism/  https://www.britannica.com/topic/syllogism  Look it up.

To determine the probability of two or more things all being true you multiply to probability of each thing together.  And yes the probability of both propositions being true will be the same if all chances are 100% nd lower if they are not.  https://www.mathplanet.com/education/pre...-of-events.  Look it up.  It's Pre Calc 101.

If you roll a pair of dice the chance of rolling a six is one in six for each die.  If you want to know what the chances are that at least on of the die will come up six, you add the probabilities together.  So, 1/6 + 1/6 = 1/3. But, if you want to know what the chances are of both die rolling 6, you multiply the probabilites.p 1/6 × 1/6 = 1/36. 

Since both proposition 1 and two must be true for the conclusion to follow, it is correct to multiply the probability of the propositions together to determine the probability that the conclusion is proved as stated by the syllogism. 

The probability that your syllogism proves that the universe has a cause is dependant on both (1) everything that begins to exist having a cause, and  (2) the universe beginning to exist.  So to determine the likelihood that the syllogism proves that the universe has a cause we multiply the probability of the first two propositions together.

[Edit: Polymath correctly notes that the computation of the probability of the two propositions both being true would be affected if the the truth of one proposition makes the other proposition more or less likely. I agree. ]

Notice that I did not say that that gives us the absolute probability of whether the universe has a cause because there might other evidence besides your syllogism, that the universe has a cause.  Perhaps you might have inductive evidence that the universe has a cause?



I'll get to the rest of your response later.