Here is my full argument against pure reason as a scientific method. I am copying it directly from the thread
Pragmatism Morphed into a Reasoning System
Here is my argument supporting my position that pure reasoning can only reveal things about abstract forms, and not about reality.
From FZ's topic
The limits of reason
First, the prescriptive laws of reasoning (aka logic) cannot be proven "right" within the system of logic itself.
Second, all arguments rely on unproven axioms (aka assumptions).
All systems of logic can be put into one of two categories:
1. Deductive
2. Inductive
I explained all this in detail in my
Logic Notes thread, but let me give a rundown here.
Deductive Logic
An argument is deductive if its premises necessarily imply[/color] its conclusions. With a mandate to construct such a system of logic, one is led directly to a formal structural language that strongly resembles mathematics. It contains rules for types of inferences that can always be trusted. This should not be misunderstood to mean that deductive logic can be used to derive absolute truths about reality. In fact, deductive logic is completely silent in this regard. It should be understood as follows:
I may not know whether the premises are correct, but I do know for certain that: If the premises are true, then the conclusion must be true.[/color]
That conditional statement expresses the only idea of which we can be confident using only deductive logic. Deductive logic does not contain a procedure for testing the truth or falsity of propositions (except for some propositions
about deductive logic, of course).
Inductive Logic
An argument that is not deductively valid is inductive. The premises of an inductive argument provide only partial support for its conclusion, and as such the conclusions of inductive arguments are accepted only tentatively. This may prompt one to ask, "Why bother with inductive logic?" Good question. The answer is that it is impossible to reason about anything that cannot be known
a priori without inductive logic. So, the price we pay for inductive reasoning may be the lack of absolute support for the conclusion, but the benefit is that we obtain the ability to say something meaningful about reality.[/color] In other words, inductive logic provides a means to judge the truth or falsity of propositions, but only in a probable (as opposed to absolute) sense.
The discipline of implementing these two kinds of reasoning to learn about reality is called
science.
Continuing:
If truths about reality are destinations, then deductive reasoning is the car that gets you from one to the other. The initial post of the thread boils down to:
How far can that car get us?
Is there some limit to the understanding that logic
alone can provide? I have answered that question emphatically in the affirmative, on the following grounds:
We have two kinds of logic: deductive and inductive.
The former is concerned with arguments whose premises give absolute support[/color] to their conclusions. The problem is that it gives no decision procedure for determining the truth or falsity of propositions with absolute certainty (actually, it's damn near completely silent on the issue).
The latter is concerned with arguments whose premises give probable support[/color] to their conclusions. The advantage is that this logic does indeed either lend support to, or outright falsifies, the conclusions that are brought under its analysis.
Since those are the only two kinds of logic at our disposal, I state that absolute truths about reality (known absolutely!) are beyond the capacity of human logic.