Rationality and Irrationality

Rationality and IrrationalityAuthor(s): David CharlesSource: Proceedings of the Aristotelian Society, New Series, Vol. 83 (1982 - 1983), pp. 191-212Published by: Wiley on behalf of The Aristotelian SocietyStable URL: http://www.jstor.org/stable/4544999 .

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XII -RATIONALITY AND IRRATIONALITY

by David Charles I

Abel, the acratic, has weighed up the advantages and dis- advantages of continuing to smoke cigarettes. He realizes that although he finds smoking relaxing, the pleasure it brings is not worth the risk he runs of irreversible damage to his health, and so concludes that in the light of all his evidence it is best never to smoke again. His brother, Cain, the continent, goes through a similar pattern of reasoning, and reaches the same conclusion. At a party they are both offered a cigarette, remind themselves of their previous best judgement and remark that nothing has happened to change their assessment of the evidence. Cain, therefore, declines; but Abel, while fully aware that he is acting against his considered best judgement, accepts and smokes the cigarette intentionally and (apparently) freely.

Abel's action is theoretically puzzling because of the strain it imposes on our standard conceptions of intentional and free action and of irrationality. If one accepts that:

(P1) S does x intentionally - S has a reason for x-ing, intends to do x and S's reason is the cause of the x-ing;

(P2) S does x intentionally - S's action can be rationally explained by S's reasons (S's antecedent desires and beliefs);

(P3) If the action is rationally explained, it is rational; (P4) It is irrational to act against one's considered best

judgement,

it follows that Abel's apparently irrational action is, in fact, impossible. Given these premises, if an action is intentional, it must be rationally explained and hence rational. Irrational

* Meeting of the Aristotelian Society held at 5/7 Tavistock Place, London WC1, on Monday, 6 June, 1983 at 6.00 p.m.



192 DAVID CHARLES

action is not rationally explained, and hence not intentional. If Abel's action is possible and is irrational, either not all intentional action is rationally explained or not all rationally explained action is rational. In either case, the assumptions about intentional action, intention and rational explanation expressed by (1) (2) (3) and (4) cannot all be maintained.

Abel's action (if it is possible) is irrational because his intention to take the cigarette is not supported appropriately by his considered judgement that it is best to abstain. Is this a failure of reasoning, and if so, of what type? In theoretical reasoning, a belief is irrational when its truth is inconsistent with the overall balance of the reasoner's evidence, and is formed typically when the reasoner is beset by self-deception, stupidity, recklessness or a failure clearly to grasp his relevant evidence. If practical reasoning is parallel, Abel's intention should be inconsistent with the overall balance of his evidence for similar reasons. But, pre-analytically, we do not represent him as overcome (in the central cases) by these intellectual vices when he forms an intention against his better judgement. How then does Abel's better judgement support a given conclusion which is the content of the intention which he should have formed, and which Cain does actually form? Alternatively, if there is no support of this type, in what does the specific and distinctive irrationality of the acratic Abel consist? Why is an intention always irrational when it fails to correspond appropriately to an agent's best judgement, when an action need not be irrational when it fails to correspond appropriately to the agent's intention (e.g. in cases of deviant causal chains) unless the former, and not the latter, involves a failure of reasoning?

A complete account of irrational, intentional action requires an explanation both of how such action is intentional, and why it is irrational. The principal focus of this paper is on the second issue: the irrationality of the acrates. My aim is to investigate whether this consists in a failure of practical reasoning whose premises support a conclusion which represents the content of the intention which Abel should have formed, and which Cain did form. This should provide the basis for an account of the nature of intention in general, and the type of rational explanation required if intentional acratic action is possible. But both of these issues require separate extended treatment.



RATIONALITY AND IRRATIONALITY 193

II

(i) Donald Davidson has suggested that practical reasoning is inductive in character, and strongly analagous to probabilistic reasoning.' In particular, he distinguishes two parallel stages which may be represented as:2

A Practical Probabilistic (1) E makes it best that. A is (1 ) E makes it most to be done. probable that. A will

occur. (2) A is best. (2 ) A is most probable.

Cain draws the conclusion that

(2) A is best

from

(1) E makes it best that. A is to be done

where E is his total available relevant evidence, as the rational reasoner in the probabilistic case concludes that:

(2 ) A is most probable

from

(1 ) E makes it most probable that. A will occur.

in line with a Principle of Rational Acceptance:

Draw the conclusion supported by all your available relevant evidence.

In the practical case,

(2) A is best

represents Cain's intention to do A, while

(2 ) A is most probable

represents the reasoner's belief that A is most likely to occur. In the practical case,



194 DAVID CHARLES


represents Cain's reasoned best judgement, and rational choice to do A. Abel forms the intention to be represented as:

(2) B is best

while holding the same reasoned best judgement as Cain in violation of the Principle of Rational Acceptance. In the probabilistic case, when E is not equivalent to all the evidence there is,

(1 ) E makes it most probable that. A will occur

does not entail

(2') A is most probable.

if (2') represents A as, in fact, most probable, since (1F) claims only that the reasoner's present evidence shows A to be most probable. When his evidence is partial, it may support the view that A is most probable, when B is, in fact, most probable. If the parallel is exact, Abel in the case specified will not be guilty of failure to draw an entailed conclusion (except when E represents all the evidence there is), and so is irrational only because he violates the Principle of Rational Acceptance in forming an intention not appropriately supported by his evidence.

In the theoretical case, irrationality arises when some factor other than a reason for belief causes the reasoner to hold

(Z) A is most probable

while holding

(1) E makes it most probable that. B will occur.

although this factor may be conjoined with a reason for belief of the form

(O ) E1 makes it most probable that. A will occur.

(where E1 is a subset of E). The added factor cannot itself be a reason for belief: for if it were, and was sufficiently influential to lead the reasoner to hold

(2') A is most probable




it should also lead him to hold

(2') E makes it most probable that. A will occur

where E is his total relevant evidence. Typically, the added factor will be a desire or a further psychological feature, but not a belief. If the parallel is exact, there must be in the case of reasons for action an added factor-not itself a reason-which causes S to accept

(2) A is best

given

(1) E makes it best that. B is to be done.

while also holding

(0) E1 makes it best that. A is to be done.

For if, in the causal sequence

[pf reason pro-A (e.g. 0)] - C* [intention to do A]

C* were itself a reason for action, and sufficiently influential as a reason to lead the reasoner to hold

(2) A is best

it should also lead him to hold

(1) E makes it best that. A is to be done.

If Abel's acratic action is caused in this way, it is not rationally explained although it is based on his intention to do A and caused by his reason for doing A. As in the parallel case of the formation of an irrational belief, a non-reason plays an intrinsic part in the formation of Abel's intention to do A. Abel may recognise in the causal antecedents of his own intentional behaviour something essentially surd (a non-reason). Elsewhere, Davidson identifies this feature with psychological phenomena such as strength of desire, a memory-trace of past happy A-ings, an image of happy A-ing, etc.3

This analogy with probabilistic reasoning appears to yield an account both of why the acrates is irrational, and of how he may act intentionally against his best judgement (while denying that all intentional action is rationally explained).



196 DAVID CHARLES

(ii) In probabilistic reasoning, one may move legitimately from

(1P) E makes it most probable that. A will occur.

to

(Z) A is most probable

when one believes that one's evidence is sufficient to allow one to infer that the best explanation of why one's evidence makes it most probable that A will occur is that it is, in fact, most probable that A will occur. In other cases, however, one may need to reach a conclusion from one's evidence which is not of type (2): e.g. if one does not believe that the evidence one now possesses (or can now obtain) is sufficient to warrant an inference to (2) For example, a doctor seeking the causes of an epidemic may need to form a hypothesis quickly on the basis of limited evidence so as to prescribe the best line of treatment, but realize that he lacks sufficient evidence to conclude that A is, in fact, the most probable cause. He would, if cautious, conclude:

(3) A is the most strongly supported of my present hypotheses

and take this as equivalent to

(3") A appears most probable from my present viewpoint,

where the present viewpoint is his present doxastic perspective, and is defined by

(a) what I can now believe (my present hypotheses), and (b) my present information and beliefs relevant to the hypotheses I can now believe (including amongst this class my present estimate, if I possess one, of what evidence the future will provide).

This judgement, although sufficient for action, is not equivalent to

(Z) A is most probable.

For the doctor would deny that his background belief entitled him to hold this. Indeed, if A turned out not to be the most probable cause of the epidemic, he could justify his action by saying




(3;") A appeared most probable from my past viewpoint

and would not take this claim to be shown to be either incorrect or unwarranted in the light of subsequent events. For (3 ") is scope-limited to his past doxastic perspective, although not explicitly relativised to it as its ground.

There is a corresponding example in practical reasoning: a tramdriver is driving a tram on a downhill stretch when it goes out of control. He can still steer the tram but cannot stop it. He approaches a fork in the line, knowing that there are two men working on one of the lines ahead of him, but (unfortunately) he does not know which. He sees on the right a pile of bricks, and on the left two chalk marks on the track. He reasons that it is somewhat more likely that the men will be working on the line with bricks by the side of it and that he should therefore go left. But he would not judge:

(2) Going left is (in fact) best

as this would not reflect his heart-felt ignorance.4 Rather he would accept

(3) Going left appears best

or

(3') Going left is best, from my present viewpoint

where the latter is defined by

(a) what I can now do intentionally, and (b) my present information and beliefs relevant to the options I can do intentionally (where included in this class will be my present estimate, if I possess one, of what evidence the future will bring).

This judgement is sufficient for action, but is not equivalent to

(2) Going left is best,

since the tramdriver would deny that he believed (2) because he judges that his background beliefs are not sufficient to warrant a judgement of this form.5 If his going left turned out not to be best, he could justify his action by saying:

(3") Going left appeared most desirable then



198 DAVID CHARLES

and thus take his original intention as the correct one in the circumstances as warranted in spite of its unforeseen and disastrous consequences. And this is because the expression of his original intention was conceived as scope-limited in its content to his past doxastic perspective, although not explicitly relativised to it as its ground. If so, there are three stages in both practical and probabilistic reasoning and not two:

B

Practical Probabilistic (1) E makes it best that. A is (1 ) E makes it most prob- to be done. able that. A will occur. (2) A appears best (2) A appears most probable (3) A is best (3') A is most probable.

In the practical case the second represents A as warrantedly desirable, the third characterises A as simply desirable. Both are non-relativised in their logical form.

(iii) There are two types of case in which the practical reasoner advances no further than the judgement that

(2) A appears best.

(A) Considered Case. The reasoner considers all the evidence he can obtain from his doxastic perspective either individually or by taking a view about the evidence he has not obtained (but could). He judges that:

(1) E makes it best that. A is to be done; and (2) NOT (E" makes it best that. A is not to be done)

where En is the most inclusive set of evidence he can then obtain, but notes that

(3) En is not adequate to support an inference to the conclusion that A is best.

However, if the conclusion is

(2) A appears best

and his doxastic perspective is defined as above, the inference from stage 1 to 2 appears indefeasible. The very same grounds (En) cannot support both the explicitly relativised claim (1) and




the judgement (2) which, although non-relativised, is implicitly scope-limited to those very grounds. If one knows that

'From an all things considered perspective, A is best',

and the sense of 'Apparently', and the specific doxastic perspective relevant to this case, one knows a priori that

'Apparently, A is best'

is true. But if the inference is indefeasible, it is a simple logical blunder to fail to move from (1) to (2) in a considered case of this type.

(B) Non-Considered Cases. The reasoner judges:


but knows that he has not considered all the evidence he can then obtain, and has no view about how the unassessed evidence would affect his assessment of what is best. In some cases, when he does not assess all the evidence he can, his final conclusion will be scope-limited only to the evidence he has assessed (E) and the inference will again be indefeasible. But not in all; he may elsewhere be represented as holding that A is best not merely in the light of the evidence he has assessed, but given all the evidence he can obtain (or even needs). The connexion here is defeasible as the grounds to which (1) is explicitly relativised are a subset of those to which

(2) A appears best

is scope-limited. However, with these scope limitations, it is not rational to conclude either

(2) A appears best or

(2') B appears best

given (1), as S-ex hypothesi-has no view about the relevant significance of the sub-set of reasons in (1) with respect to the scope-limitations implicit in (2). This would be a rational step only if S had some ground to believe that the evidence he had assessed in (1) significantly indicated the balance of relevant evidence he could assess at that point. In both cases, S shows



200 DAVID CHARLES

rashness of judgement in moving to a conclusion of this type at all. But this cannot characterise a central case of acrasia in which it is rational, given (1), to reach an intention to do A and irrational to reach an intention of the same type to do B; for here it is irrational for a reasoner to conclude, from the same doxastic perspective, either:

(2) A appears best or

(2') B appears best

as defined by the same scope-limitations. What is required to represent a central case is one in which intending to do A is rational, and from the same doxastic perspective, intending to do B is irrational without the inference from (1) to (2) being indefeasible. And this is what seems elusive when a valuational conclusion of type (2) represents the relevant intention.

(iv) Judgements of the form:

(2)---appears- are shown to be sufficient for action by the example of the doctor examining the sources of an epidemic. Indeed, when the complexity of the case or the remoteness of the consequences prevent one from reasoning to a judgement of type (3), judgements of this form are required. In practical reasoning, it seems that the exception is to reach a conclusion of the form:

(3) A is best

since it is rare that one has sufficient evidence to warrant taking this as the best explanation of stage (1) or (2).

When the conclusion is in the form

(2) A appears best

its connexion with the previous stage appears either to be indefeasible or to exhibit the wrong type of irrationality for the central case of acrasia. Hence, since there can be acratic intentions in cases where the reasoner is not warranted (by his own lights) in concluding

(3) A is best




without the acrates being guilty either of a simple logical blunder or rashness of judgement, the proposed structure for practical reasoning is not adequate to capture the specific type of irrationality which characterises acratic intentional action.

There is a further difficulty. The practical reasoner may draw as his valuational conclusion either

(2) A appears best

or

(3) A is best

depending on his assessment of the evidence. In cases in which he finds the balance of evidence equal (in so-called Buridan's Ass examples) he will not be entitled to hold either (2) or (3) but only

(4) A appears no worse than B

or (4') A is good.

Since he can intend to do A in all three types of case, his intention cannot be represented by one unique type of valuational judgement. If the reasoner's intention to do A may remain constant while his assessment of the desirability of doing A increases or decreases, the appropriate expression of his intention should be distinct from those three types of valuational judgements. This conclusion is strengthened by, but does not depend on, the common-sense observation that Abel does not judge that the acratic course either appears best or is best, but rather that it is less good than doing the virtuous action. The unconditionality of Cain's and Abel's intention to do A cannot be represented by their acceptance of an unconditional value judgement in favour of A; for the unconditionality of the former will not be typically reflected by the unconditionality of

(3) A is best.

(v) What is required therefore is an alternative way of representing Abel's intention to do A which expresses its unconditionality while at the same time showing how it is irrational given his antecedent premises, since those premises in fact defeasibly support a distinct conclusion (Cain's actual



202 DAVID CHARLES

conclusion); for this will show Abel's irrationality as a failure of reasoning of the appropriate type.

This requirement could not be met by representing Abel's intention to do A merely by Abel's being in a dispositional state which leads him to do A, given ability and opportunity (as well perhaps as causing him to believe non-inferentially that he will do A). Although one could stipulate that it was rational for an agent to move from:

(2) A appears best

to an unconditional dispositional state of this type which represents his intention to do A, the account would not explain why this was irrational as the premises would not give evidence for the truth of the conclusion.6

Within a desire-based theory, the unconditionality of the conclusion might be expressed by:

(3) A is desired

and the premises by:

(1) E makes it desired that. A is to be done.

If desire aims at its satisfaction, and not at the good, the unconditional desire need not be equivalent either to:

(3) A is best

or to any valuational judgement which is unconditional in form. The unconditionality of

(3) A is desired

might remain constant independently of Abel's changing valuational assessment of doing A. However, in this case, if strength of desire or efficacy of an image of a given type lead Abel to conclude

(3) A is desired

there would be little ground to exclude them from amongst the evidence (E) which determines what is desired at stage (1). They may be represented as propositional in form:

(0) Abel's possession of a strong desire to do A makes it desired (by him) that A is to be done.




and equipped with a relevant belief.7 It seems ad hoc to deny these psychological features the status of reasons in the acratic case solely on the basis that if they were reasons they would render Abel's apparently irrational action rationally explained and hence rational. But if they are construed as reasons (within this model), acrasia would prove impossible as there would be no defeasible gap of the required type between premise and conclusion.

III

(i) Davidson's suggestion that there is a parallel between practical reasoning and inductive theoretical reasoning is not undermined by these specific objections to his analogy between probabilistic and practical reasoning. There remain distinct applications of the parallelism:

C

Practical (1) E makes it most desirable} that. A is to be done.

best (2) It appears most desirable that. A is to be done.

best f (3) It is most desirable that. A is to be done.

best J (4) A is to be done.

Theoretical (1 ) E makes it most believable]that A will occur.

probable (2) It appears most believable that. A will occur.

probable t (3S) It is most believable that. A will occur.

probable j (4f) A will occur.

in which the fourth stage in the theoretical case is non- probabilistic in form. Given a conclusion of this type, there is no ground for restricting the antecedents in theoretical reasoning of an inductive form to probability judgements. In what follows, I will use 'most believable' as a more generic term to represent



204 DAVID CHARLES

'most worthy of belief on the theoretical side, and 'most desirable' as the analogous term on the practical side.

In practical reasoning, (2) represents the reasoner's rational choice when E, which constitutes all the relevant evidence he can then obtain, is not sufficient in his eyes to justify inference from (2) to (3). (3) represents his rational choice only when the evidence he possesses is sufficient to justify (in his eyes) the inference from (2). If a reasoner holds:

(3) It is most desirable that. A is to be done

when the evidence he possesses does not (in his view) justify the transition from (2), (3) will not represent his rational choice, but a separate noni-rational judgement not intrinsic to his reasoning. In all cases, however, (3) will represent a less limited judgement than (1) or (2) provided that E in (1), or the scope restrictions in (2), do not exhaust all the evidence there is. The final stage:

(4) A is to be done

represents the reasoner's intention to do A (within a desire- based theory, his unconditional desire to do A), and may remain constant while his view of the desirability of doing A increases or decreases.

In theoretical reasoning, the final stage

(4') A will occur

is supported by

(3') It is most believable that. A will occur

only if the truth of the evidence which supports (3') is consistent with the truth of (4'), and not consistent with:

(4") A will not occur.

Provided that one believes the evidence that supports (3'), it is rational to believe (4') rather than (4'). The acquisition of new beliefs is rational only if they are consistent with the set of propositions one already believes (which, in this case, provides evidence for the truth of (3')). Consistency and inconsistency reflect the relevant connexions between the propositions at issue: reasoning to new beliefs on the basis of old requires also




that one believes the old set of propositions more firmly than one believes new propositions inconsistent with them.

Why then does, for example,

(3) It is most desirable that. A is to be done.

support

(4) A is to be done.

in the practical case? The truth of evidence for what will desirably occur does not (in general) support the truth of propositions about what will occur. Indeed, some might reasonably hold that A's being desirable is good evidence that A will not occur! Further, (4) is not the only possible style of conclusion. In other cases, the conclusion may be

(4') A!

or

(4") Oh, to A!

and hence not itself true or false, nor capable of being supported by a judgement about what is desirably true. What is required, then, is a semantical value which shows how (2) or (3) supports (4) or (4') by representing (2) or (3) as giving evidence for (4) or (4') in a way parallel to that in which, in the theoretical analogue, the truth of the evidence for (2 ) or (3T) supports the truth of (4 ). Without this, the analogy collapses, and it remains unclear how the transition from (2) or (3) to (4) on the practical side has the character of reasoning in which premises support the conclusion if consistent with it, and fail to support it when inconsistent with it.

(ii) In the theoretical case, (4) is validly drawn from (3T) only if the truth of 'A will occur' is consistent with the truth of the evidence that supports (3 ).8 If desire aims at its own satisfaction, the strict analogy would run:

(4) is validly drawn from (3) only if the satisfaction of 'A is to be done' is consistent with the satisfaction of the desire- set which supports (3).

Each desire aims at its own satisfaction. It is not possible for two



206 DAVID CHARLES

desires to be satisfied and be inconsistent, as it is not possible for two beliefs to be true and be inconsistent. In having a belief one aims at its being true (or not being false) as in having a desire one aims at satisfying it. In both cases, one aims to avoid inconsistency as this will frustrate one's aim in having a desire or belief. This is why it is irrational to believe both

(3Y) It is most believable that. A will occur

and

(4V) A will not occur

in cases where the evidence which supports (3) is inconsistent with the truth of (4~). In the practical case, it is irrational to hold

(3) It is most desirable that. A is to be done. (4) B (and not A) is to be done.

when the satisfaction at t1 of the desire expressed by (4) is inconsistent with the satisfaction at t, of the desire-set which supports (3). Provided that one has the desires which support (3), it is rational to desire (unconditionally) to do A and not B. The acquisition of new intentions is rational only if their satisfaction is consistent with the satisfaction of this set of desires one already has. The account could be generalised to the acquisition of a wider set of requirements and obligations, unconnected with desire (if there are any such), provided that their appropriate semantical value is satisfaction. The step from (3) to (4) is in both cases one in reasoning as

best *b.st supports satisfies desirably satisfies s

in a way analogous to that in which

believably p probably true su

given consistency in satisfaction (or truth) of premise and conclusion.

In neither case is this account sufficient to characterise valid inference, as in both practical and theoretical reasoning there

satisfactioni - may be more than one conclusion whose truth Js con-




sistent with the satisfaction of the desires set which supports sistent tetruth J0 beliefjspot

(33?} In Buridan's Ass examples, two practical conclusions are equally consistent with the satisfaction of the original desire-set: the theoretical analogue is two hypotheses underdetermined by the evidence one possesses. A further characterisation runs (in the practical case):

(4) is validly drawn from (3) only if (a) the satisfaction of (e.g.) 'A is to be done' is consistent with the satisfaction of the desire set which supports (3) and (b) there is no other conclusion of the appropriate form whose satisfaction is consistent with the satisfaction of the desire set which supports (3).

A rational inference is one which meets (at least) these two conditions; an inference is irrational (as in the acratic case) if it fails to meet both of these conditions. In Buridan's Ass examples the inference might be termed non-rational since it fulfils (a) but fails to fulfil (b). It lies outside the scope of this paper to test whether this yields sufficient conditions in either case. Clearly, more needs to be said about the validity of practical reasoning in general and its relation to the validity of inductive reasoning.9 For present purposes it is sufficient to characterise the practical transition from (3) (or (2)) to (4) as a step in reasoning dependent on one homogeneous semantical value: satisfaction. For this provides a basis for characterising the irrationality of the acrates.

(iii) The analogy, however, is not perfect, and difference emerges when one moves beyond consistency to consider other aspects of reasoning.

Theoretical belief aims at the truth, and is constrained by evidence for what will occur. Desire, when practical, aims at its satisfaction and is constrained only by evidence about the likelihood or ease of gaining satisfaction. Belief in aiming at avoiding falsity is compelled (if true to its aim), when confronted by inconsistency, to prefer that belief which is most strongly supported by evidence for its truth (e.g. range of confirming



208 DAVID CHARLES

experience, coherence with our explanatory theory). Thus, when confronted by inconsistency between the evidence which supports

(3 ) It is most believable that. A will occur

and

(4f) A will not occur

it is compelled to give up that belief (whether new or old) which is less supported by evidence for its truth. Desire when confronted by an analogous inconsistency between the satisfaction of the desire set which supports


and

(4) B is to be done.

aims to avoid inconsistency, but given its connexion only with satisfaction and possibility is not similarly obliged to give up one desire rather than another. Its aim is fulfilled when the reasoner achieves a co-satisfiable set of desires; and in the extreme case this could be achieved by having only one desire (e.g. the desire to do B) and seeking to eradicate the desire-set which favours (3). In less extreme cases, it may be easier to modify the member of the desire-set which supports (3) than to alter the desire to do B, and yet still be irrational to do B given that one holds that


Elsewhere, one might believe that (in a given conflict) a slight modification in the desire-set which favours (3) will render it co- satisfiable with (4) and produce greater overall satisfaction than is to be gained from refraining from doing B, and yet still hold that:


and do B irrationally. The connexions between belief, truth and evidence explain why we should surrender one rather than another of the set of inconsistent beliefs. If desire is characterised only by its connexions with satisfaction and possibility, we lack




an explanation of the same type for rejecting one rather than another of our inconsistent desires.

(iv) What is required is the ground for preferring to avoid inconsistency in the practical case by taking the desire set which supports (3) as the one to be satisfied and not the desire to do B. If desire had aimed at the good, as belief at the true (as within Aristotle's theory), it would have been rational to give up the desire to do B provided that the majority of evidence about the good favoured doing A. For this would have explained, in a way parallel to the case of belief, why it was irrational to accept a practical conclusion against the majority of one's relevant evidence about the good (as set out, for example, in a theory of well-being), which provides the basis for


However, if an account of practical reasoning can only explain why, in this case, it is rational to give up

(4) B is to be done

by recourse to an Aristotelian conception of desire,10 it must appear incomplete; for that seems open to counterexample in the case of desires for objects not thought of as good or desirable.

Desires can be criticised not just when co-satisfiable, but also when they fail to cohere with an agent's theoretical and practical beliefs. Some cannot be satisfied if the agent's theoretical beliefs are true; the satisfaction of others falsifies some of the agent's (intention-based) practical beliefs or commitments. The latter are significant because they are one of the sources which enable the agent to represent some of his present desires as more important than others as their satisfaction is seen as a part of a coherent plan for a more protracted period of time. They provide one element in an explanatory backdrop against which certain desires can be conceived of as more fundamental, independent of the sum of satisfaction they bring individually. In this way desires are open not only to intrinsic criticism (co-satisfiability, ease of satisfaction), but also to extrinsic criticism, for example, when they do not lead to maximal satisfaction or are unimportant in the light of agent's practical beliefs and commitments.



210 DAVID CHARLES

What is important in this account is that practical reasoning is open to rational influence by features extrinsic to desire in a way in which theoretical reasoning is not open to rational influence by features extrinsic to belief. It requires that the conclusion drawn at stage (4) be consistent with the satisfaction of those desires which (e.g.) are (in the reasoner's eyes) important given his practical beliefs. Since this is the desire-set which supports


the practical reasoner must aim to make his conclusion co- satisfiable with this set, rather than jettison this set itself. Practical reasoning resembles theoretical reasoning in the homogeneity of its semantical value, but differs from it by introducing as relevant certain features extrinsic to that semantical value, the related propositional attitude (desire) and consistency: e.g. importance and contribution to maximal satisfaction. These differences account for the special irrationality of the acrates. Abel regards his desire for health as more important than his desire for a cigarette, and yet fails to ensure that his intention is co-satisfiable with the desires which he himself regards as the more important to satisfy.

IV

This account of practical reasoning allows for the possibility of different types of acratic failure. Self-deception may explain why one acrates holds

(2) It appears most desirable that. A is to be done

and

(3) It is most desirable that. B is to be done.

and therefore forms the intention to do B. Another acrates may lose sight of which of his desires are important between (3) and

(4) B is to be done

but neither are necessary to account for acratic intentional action. Since desire aims at satisfaction, it is not as constrained by evidence about what is important as belief is by evidence about what is true. Abel violates a principle special to practical reasoning which does not follow from the requirement of




consistency and the nature of desire: aim at maximal satisfaction of important desires. Since this principle is not intrinsic to desire, the acrates can form a desire-based intention contrary to (3) without the degree of irrationality involved in self-deception or clouded vision in the theoretical case. " This is why intentions are more independent of what is judged most desirable than beliefs of what isjudged most believable, although the content of both may be a conclusion validly drawn from antecedent premises. Irrationality in both cases involves a failure of reasoning, but its basis and explanation will differ as the relevant reasoning and propositional attitudes differ.

Intention may be characterised as the acceptance of an unconditional, non-valuational, sentence, whose semantical value is satisfaction with the unconditional aim of satisfying the desire or requirement it expresses. This mode of acceptance might be characterised dispositionally: as being in state which leads to the corresponding action given ability and opportunity. But it need not be, if there can be acratic (non-intentional) cases in which the acrates fails to act on his intention, although able to do so. The unconditionality of the intention may be captured by the form of sentence accepted and the aim with which it is accepted. 12

It requires further investigation to test whether the account of intention and rational explanation suggested by this structure of practical reasoning is defensible in detail.*

NOTES

'In 'How Is Weakness Of The Will Possible?' (reprinted in his Actions and Events: OUP 1980).

2I represent them thus to emphasise the exact parallel between the two cases and construe the probabilistic conclusion as

A is most probable and not

A will occur. See Davidson: op. cit. p. 37. 'E' stands for a conjunction of sentences expressing the reasoner's evidence, and 'makes it best that' is a sentential connective.

3In 'The Paradoxes Of Irrationality' (Essays on Freud: ed. R. Wollheim and J. Hopkins. CUP 1982). See also op. cit. p. 42.

I I am indebted to Michael Bratman, Kathleen Lennon, David Pears, Paul Snowdon and Stephen Williams for helpful discussion on these issues.



212 DAVID CHARLES

'Michael Bratman discusses a similar case in 'Practical Reasoning and Weakness of the Will', Nous 1979 p. 161. He also concludes that the practical conclusion is not a valuational judgement: but his reasons differ from those put forward here.

'Compare Davidson's view in 'Intending' (Actions and Events pp. 99-100) He claims that the background beliefs are never part of the content of the intention, and thus cannot distinguish the two cases here separated.

6If one is drawn to this view of intention (see C. Peacocke: 'Intention And Acrasia' in Essaysfor DonaldDavidson; ed. M.P. Hintikka and Vermazen Reidel: 1980), one requires a different account of the irrationality of the acrates.

'See Davidson: 'Actions, Reasons and Causes' (Actions and Events pp. 4-7). There is a general difficulty as to why such psychological phenomena are not reasons for action within the liberal conditions which Davidson outlines.

8 Evidence (or desire) will be taken to support ajudgement only if it positively supports it rather than the other alternatives considered.

'Bernard Williams notes certain difficulties for this type of approach: see Problems Of the Self pp. 152-155 (CUP 1973).

?For further details see my Aristotle's Philosophy Of Action (Duckworth 1983). 11David Pears emphasises the difference between these two cases in 'Motivated

Irrationality' (PASS 1982 pp. 174-177). 12 In section III a desire-based account of intention is used only as a means of illustrat-

ing what is distinctive of practical reasoning; it is thus left open whether intention is, in fact, a form of desire.



Rationality and Irrationality

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