Well, the value of Occam's Razor is predicated on certain things, like that the person involved is interested in discovering what is true in the world around him, or has goals which he'd like to accomplish, etc.--things which, based on the strict skepticism you've advocated, you're likely to dismiss as meaningless. :)  If a person doesn't care for those sorts of things, then obviously Occam's Razor ceases to have meaning (along with just about everything that could be discussed).

But, within the context of those things, here's my answer: you "can" do anything you'd like.  A person doesn't need a theory to only explain A, B & C -- he can develop one that incorporates an entire undiscovered alphabet of data should he like.  But Occam's Razor is concerned with what is "best" to do:

We live in a world with competing theories on various subjects, and we must choose which of those theories to adopt as our own.  The reason we must so choose is because 1) there are things that we want, and 2) we must make decisions.  When confronted with a situation in which we must make a choice, generally one choice will bring us closer to that which we want, others less so.

The choices we make will ultimately depend on what we believe to be true--the theories we've selected, whether consciously or unconsciously.  We are able to make "good" choices (leading us closer to what we want) in so far as our theories accurately describe reality.  The better our theories, the better our chances of making the right decisions.

For any set of data points that need an explanation (like my A, B & C), an infinite range of theories could be advanced to explain them, most of which will require some other letter or combination thereof, which are not known to be true, and may be false.  While there are no logical means to distinguish between a theory that insists on, say, M versus one that insists on P, the theory that explains A, B & C, no more and no less, has this going for it over all others: all of its data points are known to be true.

By fitting your theories to the known facts--incorporating all that which has been proven (A, B & C) while dismissing all that which has not (D, E, F, G, H, I, J, K, L, M...)--you are minimizing your exposure to error.  You are giving yourself the best possible chances, based on what is known, to make the right choices.

It's no guarantee for any given situation; with strict adherence, you can and will continue to make errors, as will everyone else (D sometimes ultimately proves true, at which point it is proper to adjust your theories accordingly).  But over a long enough life and a large enough number of decisions made, I believe that Occam's Razor will mean a smaller percentage of error overall than any strategy of blindly choosing "unproven letters" upon which to make your choices.

There's your problem, son. Just because it's the best explanation doesn't make it obligatory.  If we could say that one model of car was the best, that wouldn't force anyone to choose it ... but it would be sensible, because it's the best.  

How is it you can say in a sentence what takes me a whole page? :)  I'm sincerely jealous. 

 But you said it was the only one we could take justifiably, which would mean the only one.  And what makes it the best, anyways?

EDIT: Oh, just a second, donathos.  I didn't see you're other reply.

EDIT 2: Nevermind, this will be fine.

"Justifiably" not "possibly."  And "best" seems to be the word that you've used (But I do not see why the one that best explains the situation), but beyond that, my reply to you does attempt to address the standard of "best" here:

Is this unsatisfactory?

Though, really, my mission here wasn't to prove Occam's Razor to you (because, like I said, Occam's Razor will rely on certain principles that I already know that you disavow... as will claims that the sky is blue or the earth is round ;), just to make clear what Occam's Razor is and how it operates.

But you did say, "...the most simple solution is the only one we're justified in adopting".

In any event, I understand the need to make a choice, it's just that I don't think Occam's razor is any help.  Of course, if you say Occam's razor depends on things I've denied, then I guess I shouldn't bother arguing this specifically.

...you know there's a sky? ;)

Actually, I'd disagree about that. Occam's Razor is only about making the superior choice given available data; it doesn't attempt to guarantee the validity of the data either way nor that the choice is necessarily correct. It's just the best one, of the available choices, and given the available data -- like I said in (3) of my post above.

I think that when he says "...the most simple solution is the only one we're justified in adopting" he means that there is no justification for inventing further complexity than is required to explain things. This is different from saying that there is no possibility of a more complex explanation being more correct.

I wonder if the reason you "don't think OR is any help" is that it does not provide an absolute solution? I think we can all agree that that's the case, but we don't agree that it means OR is totally worthless.

Oops.

Justified by the evidence.  You can adopt a solution that relies on "D," but since D is unknown/unproven, the adoption of that theory is as yet unjustified.

I think that this is generally true:  Once you've dismissed the ability to make judgements, as such, all other "arguements" become futile.  On what basis could we reasonably discuss health care, or baroque music, or how to properly hang the toilet paper (so that the sheets hang away from the wall, not next to it), when there's not even agreement on if a person can assess whether or not the sky exists?

However, a truer true   is that, deep down, you don't really believe the skepticism that you've advocated here.

Like we've discussed, you live your life as though the judgements you make based on the sense data you receive are true, otherwise our conversation here would be impossible because you would have died long ago.

Yes, yes I do.  Just as well as you know it. :)

While I have the urge to argue the first thing you said, I'd rather not start a 50-post argument again; so will just agree to disagree, eh (pardon the cliche)? :)

 It isn't that I've dismissed the ability to make judgements; just ones on sense data.  Actually, I think you can do that, too. It's just that in orde to, one must take that axiom, an axiom that's wholly axiomatic.  So, I think you can discuss Healthcare if you'd like, it just requires that assumption (that is, I posit that it requires one).

I would have died long ago, if you believe your own judgements .