All of these examples suffer the same defect -fatal defect.
But to take just the last one you believe the computer is front not SIMPLY because you see it. You also have decades of experience that has confirmed almost every time that what you see IS REALLY THERE.
Not according to David Hume or Bishop Berkeley.
This has been true since were in your crib reaching for a toy. You have l o-o-o-ng ago learned to accept that what you see IS there. And are most surprised if this turns out NOT to be the case.
I don't think I have ever "learned" that there is an external world. It's just something I've always assumed. As Hume (and others) have pointed out, it's notoriously impossible to prove that there is an external world of objects.
In all of your other examples the same argument applies. You can verify by investigation - and indeed at various times in your past you HAVE verified by investigation - that your perception or belief is accurate. You no longer go thru that process because you don't need to.
Reminder: I am simply making the distinction between beliefs formed in the basic way (i.e., they are not dependent on evidence or arguments) and beliefs formed by way of evidence (or beliefs formed on the basis of those formed in the basic way). My claim is that some basic beliefs count as warranted. You seem to be saying that a belief is warranted only if it is (perhaps only in principle) verifiable.
You have (quite rightly) focussed on perceptual beliefs because those sorts of beliefs are most amenable to your argument. Sadly, your argument isn't nearly as strong as you think it is. First, I haven't learned by experience that my perceptual faculties are reliable. I have simply always assumed it. As it happens, I've never had their reliability questioned, let alone had to investigate whether they are. Yet I still think that the vast majority of my perceptual beliefs have warrant.
I acknowledge that, as we develop from embryo to adult, our cognitive faculties grow and develop. There's a sense in which that's "learning", but it certainly isn't anything like "investigation" or "verification." Babies learning to perceive depth, or learning to associate sounds with things in the world so that they turn their heads in response to their parents' voices are not processes of verification or investigation. The baby isn't learning to trust her perceptual and cognitive apparatus. This is just their normal development. (Besides, do babies even
have beliefs?)
So your whole argument about verification seems predicated on a misunderstanding of what counts as verification and investigation. It also confuses the development of faculties with learning to trust them.
Putting those confusions aside, I still don't need to verify that there's a computer in front of me in order to know that there is. My perceptual belief is warranted whether anyone verifies it or not.
But it's also possible for me to have a warranted perceptual belief that is not verifiable. I have incredibly good hearing, much better than any other human. I can hear sounds in ranges that not even dogs can hear. I hear a high-pitched sound beyond your range, and thus form the belief that I hear that sound. It seems to me that my perceptual belief is warranted even without verification. You can't verify my belief by any means whatsoever. Yet it's warranted for me (whether it is for you is debatable).
Authority says something is so you accept absent anything to the contrary. But you could if so inclined verify every statement or observation made. So could any OTHER observer so inclined.
Not necessarily. If a mathematician tells me that mathematics is incomplete, there's no way I can verify it. I simply don't have the ability to follow complex mathematical proofs. Abstract logic frequently gets the best of me, especially when it goes beyond basic sentential logic (don't get me started on modal logic or relevance logic -- ugh). So it's not even possible for me to verify this truth (or any other higher mathematical proof). Yet it seems to me that my belief in the incompleteness of mathematics is entirely warranted, coming as it does from an authority in the field. My belief remains warranted unless I'm presented with other recognized experts who disagree. Until then, my belief has warrant. If it's true, it's also knowledge.
You're right to say that someone else might be able to verify the proposition. But then, for me, that just counts as another testimony. My belief is still based on testimony, which means that I've formed it in the basic way, without evidence.
But your invisible fairy god father . . . now there's a problem.
It's a problem only if verification by empirical means is necessary for knowledge claims. It's not, so it's not.
I noticed that you steered clear of focussing on the other forms of basic belief that I mentioned. I can only assume that they are less congenial to your verification argument. Be that as it may, my claim is rather modest. I'm only saying (a) we form beliefs in the basic way; and (b) at least some of those beliefs are warranted sufficiently for knowledge. The next (admittedly more controversial) step in my argument will be to argue (c) belief in God can be arrived at in the basic way, and (d) such beliefs can be warranted. If true, such beliefs count as knowledge.
