# Making an argument valid? I need help

this is the argument in question.

The universe is complex and organized If so, the universe must have been designed But if the universe is designed, then there is a designer. So, there is a designer. So, God exists.

I have spliced it into premises.

1. The universe is complex.
2. The universe is organized.
3. The universe is complex and organized.
4. If the universe is complex and organized, the universe must have been designed.
5. The universe was designed.
6. If the universe was designed, then there must be a designer.
7. There is a designer.
8. If there is a designer, then God exists.
9. God exists

I am trying to put this into logical form. If "the universe is complex = A", the "the universe is organized = B", "the universe must have been designed = C", "there is a designer = D", and "God exists = E".

A

B

A^B

(A^B)→C

C

And this is where I'm getting stuck. How do I then move from C to D? And then from D to E? Should it be..

[(A^B)→C]→D? And then the same idea to get to E?

Also, does anybody know any resources that can help me practice putting arguments into logical form/making them valid?

Thanks

• Aside: "splice" means the opposite of what you intend here: en.wiktionary.org/wiki/splice Feb 3, 2018 at 6:03
• Re argument 6, "was designed" is just a passive voice way of saying there exists something that designed the Universe. It doesn't limit us to a single designer, or even a sentient designer-- perhaps physical laws designed the universe. Also, if God is complex and organized, He/She/It must also have been designed...
– user935
Feb 5, 2018 at 19:06

Firstly, make sure you keep the words the exact same for each step. This isn't an issue here, but it could be at other arguments.

A = The universe is complex.
B = The universe is organized.
C = The universe must have been designed.
D = There is a designer.
E = God exists.

And this is where I'm getting stuck. How do I then move from C to D? And then from D to E? Should it be..

Just do it step by step. This way you can clearly differentiate the premises. Here's one possibility of writing it:

1             (1) A                        Assumption
2             (2) B                        Assumption
1,2          (3) A ∧ B                  ∧ Introduction 1, 2
4             (4) (A ∧ B) → C        Assumption
1, 2, 4     (5) C                      → Elimination, 4, 3
6             (6) C → D                 Assumption
...

How you format it depends on what convention you're used to. The important thing is to not deviate from whatever system you being using.

As for resources, here's one: http://philosophy.hku.hk/think/sl/intro.php

edit: My formatting didn't work at first. Now it does but isn't pretty.

• Wow, thanks for that resource, that looks great. As for the PL, I'm still not sure I get step 6. I think perhaps I'm getting validity confused with soundness. I still want to ask, but how can we say "if C then D" if D is just coming out of nowhere, has no basis for acceptance. But I suppose we're no concerned with basis for acceptance, which is why you labeled them assumptions. Which is very helpful btw! Otherwise I think I'd still be confused Feb 3, 2018 at 0:49
• Everything labeled "Assumption" is a premise for the argument. Everything else follows from the premises with inference rules. The numbers on the left side are supposed to keep track of which premises are getting used. The numbers in the brackets just number each step. On the right we have a description of what exactly we're doing in the step. So if we add the last few steps without mistakes then we'll know the argument is valid. "Valid" means if the premises are true then the conclusions must follow. "Sound" means validness + true premises. Feb 3, 2018 at 2:54
• you could put the argument in a <pre></pre> block, this switches to a mono space font and thus you can do better ascii art.
– Dave
Feb 3, 2018 at 14:16

Predicate 6 should be a premise of your argument, not derived from your previous premises, like predicate 4 is. The same applies to predicate 8. Predicates 1, 2, 4, 6, and 8 are the premises of your argument, and predicates 3, 5, 7, and 9 are derived from your premises.

• Can you explain that a bit more? Are you saying that predicate 4 is a conclusion as opposed to a premise, but that premise 6 is not? Is that because a conclusion has to be derived from previous premises (as 4 is), and so 6 is then just a plain old premise, an assertion essentially? That makes enough sense, but I'm not sure how to articulate that into propositional form? Feb 3, 2018 at 0:44
• Aside: a predicate isn't the same thing as a premise. Premises are complete sentences, like "the cat is asleep." Roughly, predicates represent properties of objects, like "is asleep." Feb 3, 2018 at 6:07
• E.D.'s point is that step 6 of the argument is an independent assumption. It's not derived from any of the other claims. Different systems of notation have different ways to indicate assumptions. In Marc H.'s answer, assumptions are indicated simply by writing "Assumption" in the final column, and derived steps are indicated by writing the inference rule and steps used. Feb 3, 2018 at 6:13

My impression is that you are constructing an argument with the purpose of reaching a specific conclusion. The conclusion you are hoping to reach: "Therefore, there is a designer (God)." The argument goes basically like this: "The Universe is so complex and organized that it could not possibly have come into existence unless it was designed."

If you accept this logic, you are basically saying: Because the Universe is too complex and organized to exist on its own, it must have been designed by an agency that is infinitely MORE complex and organized.

Now you are faced with the EXACT same question. You have only pushed it one step further and made the question doubly complex. If God is complex and organized enough to create the Universe, then God is too complex and organized to have come into being without the action of some higher agency.