Tuesday, April 12, 2005

LBDES: Plausibility Reckoning

As part of the Looking Back Down Explorer Street series of posts...

Determining the plausability of a claim is one type of reasoning task, which I am calling plausability reckoning. Naturally, some of the means by which we undertake plausability reckoning are flawed.

One such means uses imagination as a judge. The plausability of a claim is tested by trying to imagine some situation or way that the state of affairs could arise or have existed. And if the imagining comes up blank, the judgement is: not plausible.

Unfortuantely, imagination is a poor judge at this, because it simply can't match the complexities of the world. The possibility that coming up blank is a limitation of your imagination looms much larger than the possibility that your imagination has a correct insight into the nature of reality.

To consider one type of claim, of whether some thing will be possible in the future, it means little if a person can't imagine how the thing could become possible. In the realm of technology, for example, the possibility is always impacted by future technological advances which we in the present are not privy to.

Another flawed means of plausibilty reckoning is to compare this thing to what we are familiar with and to reject it if it seems too different. This is really just a special case of the first means. You are again assuming that if the thing is plausible, you ought to be able to find some positive justification for believing it is -- such that lack of such positive justification implies implausibility. In this case the supposed justification is that it is like other things you know exist.

On this blog I noted down two examples of flawed plausibility reckoning, one historical, one recent. The historical one involved an early description of geisers that was submitted to a publication but rejected because they "don't print fiction". The more recent involved giant ocean waves that were rejected as myths but are now known to exist.

I think that we have a tendancy to look back on such things as being reasonable judgements for their time and place, thinking "any reasonable person would have made the same judgement". This expresses a belief that there is no reliable means for avoiding such mistakes. But while it seems likely that there is no universal method, what we can do is rule out all the means that, while intuitively appealing, are not reliable. As I believe these means are.

I believe a more adequate approach, instead of trying to find a reason why the thing might be possible, is to see if you have any good reason for believing it couldn't be possible. If you can't find any good reason then you have no grounds to reject it. This doesn't mean you believe it is definitely true, it means you have no grounds for making a judgement. And this is okay.

There's a belief that we always have to make either a yes or no (approval or disapproval) judgement on thing. We can't sit there without making a definite judgement. But I believe this is in fact false. Quite often there is no reason at all to make a one-way-or-another judgment, and not even a reason to make any sort of judgement (I haven't done a proper justification of this yet).

Even if we do need to take some action based on our judgement of the thing, what we need is a definitive action not some definitve belief about the actual plausiblity. What we can do is make a judgement of what is most likely and then go one-way-or-the-other through the action that we take. It is our actions that require definitiveness, not our judgements of the situation -- we can be definitive with our action and still undecided about the plausibility.

People seem not to decouple judgements from their actions. If there is a need for definitive action, they see it as a need for definitive belief, and this leads to some degree of dogmatism, which fills the void of a substantial justification for the judgement made.

The flawed means of plausability reckoning by trying to see a reason why the thing might be possible, and rejecting if you can't see such a reason, is an example of our overconfidence in our perception of the world. We think that because we can't see an answer, an answer must not be there. As such, we need to always take the nature of our own perception into account, and consider whether one of its limitations could be responsible how things seem to be, and not the world itself.

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