[D-fendr]

Moreover, he uses observation as evidence for his opening premise, but not for his conclusion.

So long as the conclusion is not contradicted by observation (and the logic is correct) it stands as a viable argument.

In fact, there are observational discoveries driven by just such arguments: If we observe A, B must exist...

It is true that "B" in the first cause argument has not been observed, but that does not in itself negate the conclusion.

I would call that a leap of faith as well as consistency.

No, again, it's not fancy, not a leap of faith, it's a logical argument.

If the source of our knowledge is observation then we certainly don't know that there is an uncaused being, do we?

Observation is one source of knowledge, but not the exclusive one.

[kosta50]

So long as the conclusion is not contradicted by observation (and the logic is correct) it stands as a viable argument.

His conclusion is not valid because it violates his axiom that no object (no thing) can cause itself.

Observation is one source of knowledge, but not the exclusive one.

Observation is the only form of objective (phenomenological) knowledge and it's method of discovery is a posteri reasoning. On the other hand, a priori approach leads to ontological arguments and subjective knowledge. The two cannot be conflated.