(Philosophy All Souls Exam Questions)
"If you were a brain in a vat, would you be justified in believing that you have hands?"
Yes. As long all input you were receiving was consistent with you having hands since it would be impossible for you to know that you were a brain in a vat. However, if the input you were receiving was not consistent with you having hands then you would not be justified in believing you have hands; unless a defect or damage to the brain in the vat prevented you from understanding whether the input is or is not consistent with you having hands in which case you would be justified in being confused or still believing you have hands.The third option is if you received no input either supporting or refuting the "Hands-Hypothesis" in which case you should assume you do not have hands until such time as evidence supporting the existence of hands is available.
"Can visually inspecting your hands provide you with a reason for thinking you are not a brain in a vat?"
Yes. Visually inspecting your hands is evidence that they do indeed exist, however for you to conclude they are 'your' hands you would could have to be able to see that they are attached to yourself or that you can repeatably intentionally move the hands (in the absence of priopreception aka body-awareness of the hands). You may in fact just be a brain in a vat and the visual or other sensory information may just be electrical impulses plugged into the brain or be generated from another part of the brain which you are not consciously aware of (like a hallucination) but these are unknowable from your point of view until such time as flaws, faults or inconsistencies arise in the inputs. Since we have no evidence such a complex and perfect system can exist you should assume your perceptions are indeed genuine (in contrast our electronics are extremely buggy).
"To what extent are philosophical questions implicitly about the use of language?"
To a large extent. Issues such as that discussed in the two previous questions are really just discuss what is meant by 'reality' and 'objectivity'. Colloquially we use 'reality' and 'objectivity' to mean what really truly exists but obviously absolute truth is impossible to know because we are restricted to whatever reality we exist in and the stuff in it we can sense/manipulate. It is because of this very impossibility that the distinction was not made during the evolution of language. However, because of the flexibility of language it is possible to express ideas and questions which are useless, meaningless, contradictory or paradoxical. For instance "What came before time began?" is a completely grammatical question but is also meaningless - there is no 'before' the beginning of time. Similarly "This statement is false" is paradoxical (if it is true then it is false and if it is false then it is true) and thus meaningless. Or another common what "What caused the first thing to happen?" (if something caused it then it was not the first thing). Language did not evolve to reveal truth, it evolved and continues to develop to facilitate communication including the communication of lies and untruths.
