Just a note and reminder that, as per the agreed debate structure this is my response to PRO's Round 3 argument (as well as defense and support of my own arguments).
Reliability of Senses
PRO clarifies that they aren't actually claiming that senses aren't reliable, just that the could be unreliable and that Empiricism doesn't demonstrate this. However, the senses either are reliable enough to provide knowledge or they are not. If the senses are reliable enough to provide knowledge, then PRO concedes the argument in my favor. It doesn't matter if a specific claim is not attainable by Empiricism itself (such as the claim that the senses are reliable) and is not necessary to prove the argument. The claim that all knowledge comes from Empiricism doesn't mean that all truths are justifiable as knowledge through Empiricism, just that all truths that can be justifiable as knowledge can be done so through Empiricism. There is an allowance that there are some truths that simply cannot be known.
The shared BOP also means PRO cannot simply take a neutral stance here either. They aren't just defending Rationalism, but Rationalism instead of Empiricism. To win this argument, PRO must demonstrate that the senses are necessarily reliable to a degree that no knowledge can be derived using them.
The Source of Axioms
PRO says I am being uncharitable, but does not disprove my statement. PRO says that they defended their axiom, but that does not refute my point. By definition
, an axiom is "an unprovable rule or first principle accepted as true because it is self-evident or particularly useful."
Thus we choose axioms because: a) they are self-evident; or b) because they are useful to achieve some specific goal. It is undeniable that the latter is a result of personal choice. I will concede that the former is not an element of choice, but self-evidence, from am epistemological standpoint, does not constitute knowledge. Furthermore, it is not necessary that a logical framework include such axioms, so there is still the element of choice that such a self-evident statement forms the axiomatic base of a given rational outlook.
Just as PRO notes that there are logical frameworks that exclude the law of non-contradiction (which many people would claim is self-evidently true), there is no reason a person can't exclude PRO's stated axioms in developing or using a different logical framework. PRO would have to demonstrate that such axioms bust necessarily be included in a given logical framework and still would have to address the fact that self-evidence isn't knowledge.
The Objectivity of Truth
PRO confirms my claim that truth requires an external basis to judge our beliefs against ("Rationalism is a theory about how we come to discover what this objective truth is"). Yet, rationalism cannot provide this. The axioms are chosen based on personal choice, as are any given rule of inference. Thus all subsequent theorems within that logical framework are a result of that choice and that choice alone. These choices strictly determine what "truths" can be derived within that framework and thus no truth can be accurately called "objective."
Without this objectivity, there is no basis against which one can judge one's beliefs to call them knowledge.
Defense and Support of Empiricism
By contrast, Empiricism, by establishing the existence of an external world through which we can attain information, Empiricism can move beyond pure introspection and judge claims against an external, objective reality that is not limited by, or subject to, our choices. The 100% reliability of senses is not required. The continued comparison of our beliefs with reality over time, and with other observers, serves to weed out potential errors. Given that 100% certain is not a universally agreed upon requirement for justification, this refinement process means that knowledge is eventually attainable.
Since knowledge can only be attained by comparison against an external, objective reality, and since Rationalism doesn't provide this while Empiricism does, only Empiricism can offer a path to knowledge.
Brain in a Vat/Hallucination Scenarios
Technically, this section only applies if PRO actually takes up the argument against the reliability of senses. The Brain in a Vat/Hallucination is a type of scenario that is oft brought up in refutation of Empiricism and similar frameworks. However, it is not given that these scenarios actually rob Empiricism of epistemological value.
Firstly: They do not eliminate the existence of an external, objective reality. The simulation or hallucination is not subject to the individual's choice or whim, so still exists as external and objective to the conscious mind.
Secondly: It does not render, strictly, false, statements made about reality itself, just our belief that the reality we are making claims about is the ultimate reality that exists, which is a separate belief. For example, if you project the holographic image of an apple on a table and I say, "there is an apple on the table," yes that statement is technically false, as the apple is fake, but bound within that simple statement are a number of implicit facts:
1. There is something there on the table.
2. It has the size, shape, and color of an apple.
So even if the statement itself, taken at face value, isn't itself knowledge, knowledge is still attained in some form.