Kaiden writes: [To Theo]
An un-weird and appropriate question. I haven’t been sure what to say because it’s not a common question I receive. But I’ll say this.
My way of coming up with the scenario was to use imagination to create a counterexample. I saw that the argument was an invalid deductive argument. One way of proving such an accusation is to give and explain a counterexample. A counterexample is a description of a logically possible circumstance in which the premise of an inference is true, but the conclusion is false at the same time and in the same circumstance.
Logical possibility here is about consistency: the sentences describing the circumstance can all be true at once, according to their form, or, seen from a different perspective, no contradiction can be derived from the sentences.
In the case of your argument, I didn’t elaborate on my counterexamples at length in my post, but the gist is that I created a story in my head in which pizza slices and billiard racks come in and out of existence, playing a role in keeping triangle in existence. As long as the circumstance imagined is within the broad boundary of logical possibility, it can be as outlandish and goofy as you like (even defy physics and metaphysics.) Counterexamples are funny, attention catching, simple and get the job done.
For the second question…
I see what you mean. However, it seems to me that the sentence in premise 2 is not expressing the statement that there are abstract objects and that there are concrete objects. Instead, it is telling us a necessary condition of the existence of abstract objects. It is stating that abstract objects are a kind of thing that need concrete objects in order to exist. As far as the second premise is concerned, there may not actually be any concrete objects so as to fulfill the condition and, accordingly, there may not be any abstract objects.
I think it's because I was assuming that dependence meant that the object (in this case the concrete object) must exist to sustain the abstract. Is there a methodology to suss out these assumptions?
This assumption could be true, as far as premise 2 is concerned. Premise 2 does not require that this is true, though, which makes room for my counterexample.