Tansu KUCUKONCU , PhD
( Tansu KÜÇÜKÖNCÜ ( in Turkish alphabet ) )
Reasoning : Mental View Revision
There are basically two theories (for normal conditions) of revision of one's mental view.
* Foundations Theory (FT): holds that some of one's beliefs 'depend on' others for their current justification; these other beliefs may depend on still others, until one gets to foundational beliefs that do not depend on any further beliefs for their justification. In this view reasoning or belief revision should consist, first, in subtracting any of one's beliefs either need no justification or are justified on the basis of other justified beliefs one has.
* Coherence Theory (CT): according to it, it is not true that one's ongoing beliefs have or ought to have the sort of justificational structure required by the foundations theory. In this view ongoing beliefs do not usually require any justification. Justification is taken to be only required only if one has a special reason to doubt a particular belief. Such a reason might consist in a conflicting belief or in the observation that one's belief could be made more 'coherent', that is more organized or simpler or less ad hoc, if the given belief were abondened.
Both of these theories have some inefficiencies to explain the situation in real life, when they are used alone.
The foundations theory seems to be more in line with our intiutions about how people ought to revise their beliefs; the coherence theory is more in line with what people actually do in such situations. Intiution seems strongly to support the foundations theory over the coherence theory as an account of what one is justified in doing in such cases; but in fact one will tend to act as the coherence theory advises.
We can briefly list the main effective factors in belief revision as below:
1. Interest Condition (on theoretical reasoning): One is to add a new proposition P to one's beliefs only if one is in whether P is true (and it is otherwise reasonable for one to believe P).
We can gather types of interest in four headlines:
a. Interest in the environment: One has a reason to be interested in objects and events in one's immmediate environment. (So one fairly automatically notices 'salient occurences' that are 'right before one's eyes'.)
b. Interest in facilitating practical reasoning: If one desires E and beliefs M's being true would facilitate or hinder E, one has a reason to be interested in whether M is true.
c. Interest in facilitating theoretical reasoning: If one is interested in whether P is true and has reason to believe knowing whether Q is true would facilitate knowing whether P is true, one has a reason to be interested in whether Q is true.
There is an important respect in which one can be interested in whether Q is true without being interested in whether not Q is true.
Granted, acceptance of not Q might be useful in keeping one from later trying that possibility again. It is useful to have some record of ways one knows one get to P. It is enough to note general charecteristics of unsuccesful routes.
d. Interest in 'not being inconsistent': One always has a reason to be interested in avoiding inconsistency.
Actually one has two tendencies:
i. tendency to avoid holding beliefs that are immediately inconsistent.
ii. a tendency to avoid holding beliefs that that one recognizes to be indirectly or less obviously inconsistent.
Beliefs are indirectly incosistent if there is a possible argument each step of which represents an immediate implication from those beliefs to conclusions that leave one's beliefs immmediately incosistent.
2. Clutter Avoidance: One should not clutter one's mind with trivialities.
3. Simplicity
4. One should make minimal changes.
5. One should not give up a belief one can easily (and rationally) get right back. (The Get Back Principle)
All these are needed because of the limited capacity of human mind (memory, speed, etc).
We can sum up all these, in a shorter way, as:
'Belief revision should involve minimal changes in one's belief in a way that sufficiently increases overall coherence'.
The basic principle of foundations theory is that one must keep track of one's original reasons for one's beliefs, so that one's ongoing beliefs have a justificational structure, some beliefs serving as reasons or justificationsfor others.
If we try to apply FT in an ideal way, we have problems because of human's limited mental capacity.
There not enough memory in mind for infinitely many justificzations.
Moreover, mental transmission speed is not enough to perform too much long justifications for each mental acceptance.
FT rejects any principle of conservatism. In this view a proposition cannot acquire justification simply by being believed. The justification of a given belief cannot be, either in whole or in part, that one has that belief.
Justifications are prima facie or defeasible. The FT allows that one can be justified in believing something P and then come to believe something else that undermines one's justification for believing P. In that case one should stop believing P, unless one has some further justification that is not undermined.
If one believes P and it happens that all one's justifications for believing P come to be defeated, one is no longer justified in continuing to believe P and one should subtract P from one's beliefs.
If one comes not be justified in continuing to believe P in this way, then not only is it true that one must abonden belief in P but justifications one has for ohter beliefs arealso affected if these justifications appeals to one's belief in P. Justifications appealing to P must be abondened when P is abondened.
Justifications cannot be legitimately be circular. P cannot be part of the justification For Q while Q is part of the justification for P.
It does not allow P to be justified by by appeal to Q which is justified by appeal to R, and so on forever.
The FT also disallows infinite justifications.
The C.T supposes one's present beliefs are justified just as they are in the absence of special reasons to change them, where changes are allowed only to the extent that they yield sufficient increases in coherence.
When it is applied alone, C.T increases the risk of making errors. One can easily miss incoherencies.
Coherence competes with conservatism. But in CT, while one resist to changes, he should not miss opportunities toincrese coherence (that's something like a tendency to maximize coherence, but with minimum change.
I think that a moderate and controlled conservatism is needed. Not all the time, but sometime a wrong method or knowledge may be better than none. In fact, that is the case in practice.
Whether a belief is justified depends on how well it fits together everything else one believes.
Nothing wrong with circular justification in the coherence theory, especially if the circle is a large one.
I think that justification is used more than supposed to be in CT. But I accept that most of the time people are not aware of the justification (that's its steps) they performed.
For example, one makes multiplications in mind, but he is unaware of how he performed those. It is something like that.
The FT says one is justified in continuing to believe something only if one has a special reason to continue to accept that belief,
where as the CT says one is justified in continuing to believe something as long as one has no special reason to stop believing it.
FT represents an idealized method for belief revision. As I said before, it would not be true to use it strictly in explaining the situation in real life. But maybe it is the only method can be used in artificial intelligence applications to minimize errors.
Here I want to give some passages from Harman:
'People simply do not keep track of the justification relations among their beliefs. They continue to believe things after the evidence for them has been discredited. They do not understand that the discredited evidence was the solereason why they believe as they do.' (1,38)
'Since people rarely keep track of their reasons, people are unjustified in almost all their beliefs.' (1,39)
I don't agree with these ideas.
Coherence involves not only consistency but also a network of relations among one's beliefs, especially relations of implication and explanation.
I think that a bit of FT, in fact, is hidden in CT. In CT some justifications always are required when the overall coherence is checked.
Therefore it would not be true to argue such things as above.
On the contrary, people keep track of their reasons. But it can be said that it is not as required in FT. It's okey. That's why I want to combine two theories. At zero point(s) (of knowledge cumulation) FT and CT are indifferent. Differences begin after some level of knowledge cumulation. Most of the time they don't keep exact tracks of their reasoning, but they keep basic charecteristics of their tracks. So, it is not true to say people are unjustified in almost all their beliefs. Their justification might be far from common sense. These might not be in universal norms. But I think that most of the time people have these tracks.
And even for FT there will always be new second-level (different than initial one) zero points, where the cumulation of knowledge would be insufficient to be a background to a new belief. Then it can be accepted or unaccepted, according to will. At these points FT and CT are indifferent again. To make critics about these points is not easy. According to the level of knowledge cumulation, amount of these point may be more in some than in others.
And I want to point out another important subject. Harman says that:
'They continue to believe things after the evidence for them has been discredited. They do not understand that the discredited evidence was the sole reason why they believe as they do.' (1,38)
In fact, Harman's argument does not mean that they don't keep tracks of their reasoning. That reason really might not be the sole reason to believe. There may be other reasons. Moreover, the discredition might be illusory, or false. Even there may be other tracks of reasoning which supports thatthat belief cannot be discredited, or which suspects about the truthness of discredition and thus resist it. That's a discredition for one might not mean discredition for another. If this discredition is proved to be a universal one, and we examine the situation for universal conditions, then it is another dimension of our subject. And I don't want to discuss it here.
Before putting the last dot, I want to sum up what I said up to here. My hypothesis is that:
In real life, in normal and contemporary conditions, when revising their beliefs, most of the time, most of the people behave according to a combinational form of FT and CT.
Some of ones beliefs 'depend on' others for their current justification; these other beliefs may depend on still others, until one gets to foundational beliefs that do not depend on any further beliefs for their justification. These should not be ideal justifications. Most of the time it is enought that that belief supplies the basic charecteristics of the required justification.
Unoccurrance or discredition of justification is a required condition not to accept or to abondan a belief, but it is not a sufficient condition by itself.
The main purpose of belief revision is to maximize coherence with minimum change.
(i,j):
i: no of the source material in the bibliography
j: pg. no.
Bibliography:
1. Change in View: Principles of Reasoning, by Gilbert Harman, The MIT Press, 1986
2. Long Run Consistency of Beliefs as Criterion of Emprical Knowledge, by Teo Grunberg, (unpublished), 1993
