i:ic skills associated with informal logic. 
':'he test 'lie are employing is the Natson-
Glaser Critical Thinking Appraisal. l It is 
being given in one version as a 'pre-test' 
at the beginning of the course and as a 
'~ost-test' at the end. The difference in 
student performance on these two versio~s 
will provide some measure of the effect~ve­
ness of the course in meeting its goals. (We 
are planning to establish a control group ~f 
students who will take the test, but who w~ll 
not be taking the course, as a way of making 
this a more accurate measure.) The data 
collected should be very helpful in per-
suading our more empirically minded col-
leagues of the effectiveness of this informal 
logic course. Additionally, it will provide 
valuable information to both the instructors 
and students. 

Informal logic will also have application 
in the Integrative Component of our new gen-
eral education program. In terms of t~e un-
derstanding of 'integration',here (obv~ously 
there are many complex issues in this approach 
to learning and education) our program inter-
prets the concept as a process concept going 
well beyond the idea of mere 'relatedness' 
which sometimes characterize attempts at in-
tegrative learning. In order to underscore 
this distinction, the program directs faculty 
who wish to teach courses in this component 
to specify the 'mechanism' of integratio~ to 
be employed. The philosophy faculty bel~eve 
that informal logic can serve admirably as 
just such a mechanism and that it can be 
employed for that purpose in a very wide 
variety of academic contexts. To give but 
one example: A program now being prepared 
for this component by Dr. Charles Krecz of 
our department, will be concerned with reli-
gion. It will involve a course in each of: 
the ohilosophy of religion, the sociology of 
religion and an anthropology course in prim-
itive religion, as well as an informal logic 
course which will concentrate on methodology, 
structure of exposition, analysis of types of 
reasoning, etc. of each particular disci-
pline's approach to the study of religion as 
well as analYsis of reasoning in religion 
drawing from-the data provided-Sy the materi-
al in the other courses. 

'Jther areas in -.. ;hich infor:::al l::>gic can 
serve as the mec::'aniSr:! of integration ::light 
incl'lde "technology and ·1a1:.:es," "the a:rts 
~:'ld er:."Ti=onment" and so .:)n. In ':act c?le pos-
sibilities are about as great as the imagina-
tion and interest of facultv and st:.:dents. 
Of course such an approach ~as the further 
advantage for those interested in informal 
logic of exposing them to a variety of dif-
ferent areas where the special characteris-
tics of reasoning in those areas can be 
analyzed. Such contact should help maintain 
vigor and 'freshness' in informal logic. 

Obviously many campuses will not be able to 
move in the precise directions we have. How-
ever, I hope I have illustrated the fruitful-
ness of looking for ways in which interest in 
informal logic can be pursued in the context 
of the debate on general education. 

10 

critical 
reviews 

CHALLENGE 
&RESPCNSE 
Carl Wellman 
Trudy Govier 
Trent University 

This book was ~ublished in 1971. It has not 
received very much attention from philosophers, 
possibly because Rawls' Theory of Justice, 
published almos~ at the same t~me, preoccupied 
many of these interested in moral philosophy, 
Challenge and Response deserves more attention 
::nan it has rece~ 'led, I think, and it certain-
ly merits careful study by those interested i~ 
in:::Qrmal loaic. ;.;ellman sets OUt to answer 
the meta-ethical question 'how can moral judg-
ments be justified?', but befQ:re approaching 
that question, raises the prior one: 'what is 
justification?' The first hal::: of ~is book is 
devoted to answering this general question, 
and, as such, contains much which is relevant 
to theorists of argument. 

After some one hundred and thirty pages of 
close argument, Wellmann arrives at his view 
of what justification amounts to: 

In my view justification is to be 
understood essentially as a process 
of responding to challenges made. It 
may be observed and described as a 
psychological struggle in which one 
person tries to force another to back 
down, or one person struggles to come 
to terms with his own doubts and con-
flicting convictions. But it is more 
than a psychological struggle because 
at its core are certain critical claims 
to truth, validity, to be upsetting, 
to be reassuring, an~ to be adequate. 
Therefore the actual outcome of any 
particular psychological struggle 
never settles once and for all the 
issues being fought over in the process 
of justification. It is this peculiar 
ambivalence of justification that 
enables what we actually do in discussion 
and thinking to serve as a test of 
critical ideals like truth, validity, 
and being justified. (pages 132-3) 

Much justification (though not all, in wellw'l 
man's view) proceeds by argument. Wellman has 
some novel and interesting things to say about, 
arguments and arguing, and it is to these that I 
I'll devote most of my attention here. He I 
maintains that there are legitimate arguments 'I 
which are neither inductive nor deductive (he 

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names them 'conductive'); redefines "valid"; 
endorses the notion of nonformal validity; de-
fines "induction" in an original way; relates 
the notion of burden of proof to old-fashioned 
discussions of rules for directing the mind; 
and takes on the hoary problem of missing pre-
mises. Obviously this is a rich source; I 
cannot discuss all these topics here. 

First of all: deductive, inductive, and 
conductive. As Perry Weddle has argued l , 
definitions of "inductive" and "deductive" are 
so unsatisfactory that it seems premature to 
ask whether all arguments fall into one of 
these two categories. Anyone who tells us 
that there are arguments which are not either 
deductive or inductive had better clarify his 
position by explaining what he takes inductive 
and deductive arguments to be. Wellman's 
definition of deductive argument is fairly 
traditional: 

Deduction is that form of reasoning 
in which the claim is made that the 
conclusion follows necessarily from 
the premises. If it is possible for 
the premises to be true and the con-
clusion false, then the argument is 
invalid; if the truth of the premises 
is a sufficient condition for the 
truth of the conclusion, then the 
argument is valid. (page 4) [my emphasis] 

His definition of inductive argument, however, 
is not. 

By "induction" I mean that sort of 
reasoning by which a hypothesis is 
confirmed or disconfirmed by estab-
lishing the truth or falsity of its 
implications. To show that the con-
sequences of some hypothesis are true 
is to provide evidence for its accep-
tance; to show that one or more of 
its consequences are false is to 
refute it. It is this sort of 
reasoning, so important to science, 
to which I refer by the word "in-
duction". (page 33)2 

In the definition of deduction, the phrase "in 
which the claim is made" will give rise to 
problems. For typically, that 'claim' will not 
be explicitly expressed, and we will have to 
judge whether the premises are supposed to make 
it impossible for the conclusion to be false, 
or whether some looser connection is intended. 
Often this will be difficult. Consider: 

It is the singular feature of such 
ethnic explanation (of poverty) 
that it is all but exclusively con-
fined to conversation. The repu-
table scholar unhesitantly adverts 
to it in casual interchange but 
rarely if ever puts it in his 
books or even his lectures. What 
is wholly plausible in conversation 
is wholly impermissable in print 
There is obviously something odd' 
about an explanation of poverty and 
well-being that must be so discreetly 
handled. (from Galbraith, The Nature 
of Mass Poverty, pages 14-15) 

Galbraith is arguing from the absence of this 
form of explanation in print and in lectures 
to its being an odd explanation. Does his 
argument 'involve the claim' that the ~remise 
makes it impossible for the conclusion' to be 

11 

false? It's hard to know what to say in re-
sponse to this question. The same situation 
arises with: 

• • • the combination of science and 
intellectual history is an unusual 
one. Initially it may therefore seem 
incongruous. But there can be no 
intrinsic incongruity. Scientific 
concepts are ideas and as such they 
are the subject of intellectual history. 
(from T. S. Kuhn, The Copernican 
Revolution, page vii.) 

Discriminating deductive arguments from others 
on the basis of what connective claim 'is made' 
isn't easy, and here Wellman shares difficul-
ties with logical tradition. 

Standard textbook accounts define deduction 
as Wellman did, and then go on to define in-
ductive arguments as those which 'involve' or 
'make' the lesser claim that premises only 
make the conclusion more likely or probable. 
In these accounts, the full weight of the in-
ductive/deductive distinction falls on the 
matter of the claim made (implicitly) in the 
argument. Also the inductive category looks 
like a bit of a grab-bag; inductive arguments 
are just all those arguments which aren't de-
ductive. In view of these facts, Wellman's 
rather different account of induction is 
worth studying. 

Inductive arguments, for Wellman, will be 
those arguments for or against hypotheses, 
from the confirmation or discomfirmation of 
those hypotheses in specific instances. Thus, 
'these 100 crows are black, so all crows are 
black' would qualify as an inductive argument. 
Also, as Wellman points out, scientific rea-
soning is frequently inductive in his sense; 
particular observations and experiments are 
brought to bear on more general hypotheses. 
Induction in some sense is still widely 
thought to be the method of science, and most 
inductive logics deal exclusively with sci-
entific confirmation and disconfirmation. 
Where Wellman's definition starts to have non-
traditional consequences is in its permission 
of a priori induction 3 . Reasoning for or 
against general ethical principles on the 
basis of conclusions about specific instances 
would count as induction. If we were to argue, 
contra Kant, that lying is not always wrong, 
because it would be permissible to lie in 
order to save a life, we would be using an in-
ductive argument, in Wellman's sense of "in-
duction" • 

Ethical theories, just like scientific 
ones, have specific consequences for 
particular cases. If these con-
sequences are found to be true, 
this confirms the theories. If they 
are found to be false, the theories 
are disconfirmed. However differently 
the consequences may be found to be 
true or false, the truth or falsity 
that is found has the same logical 
relation to the hypothesis of which 
it is a consequence. Therefore, 
inductive reasoning has its place in 
ethics just as it has in science. 
The logic of science is also the 
logic of ethics; the confirmation 
and disconfirmation of hypotheses 
is common ground. (page 44) 



On the other hand, some arguments which tra-
dition would call inductive do not seem to be 
inductive by Wellman's definition. Consider: 

I've been a Supreme Court justice for 
25 years, and never have I known any 
Supreme Court justice to divulge to a 
journalist the vote on any court case, 
If this journalist says that a justice 
told him there was a 5~4 split on the 
Stephen Truscott case, he must be 
lying, 4 

This argument is of the type 'never in my ex-
perience, X; therefore not X in this case', 
It is much like 'never has the sun failed to 
rise, so it will surely rise tomorrow', and 
would surely count as inductive according to 
logical tradition. Yet the argument appears 
not to be inductive in Wellman's sense, for it 
applies a general hypothesis to a particular 
case, rather than moving from a case or cases 
to a hypothesis, 

I shall not pursue this matter' further, 
for, given the problems which have been found 
to arise in standard accounts of inductive 
and deductive arguments it does not count as 
much of a criticism of Wellman's distinction 
to point out that his rather novel definition 
of "induction" fails to include all the old 
examples as inductive. His definition pre-
serves a link between induction and science, 
and between the relation between confirmed/ 
1isconfir~ed p3rticular judgments ar.d a gen-
eral hypothesis. However, it allows for non-
empirical induction and may fail to classify 
some probabilistic arguments as inductive, 
Also, it does not distinguish inductive from 
deductive arguments in such a way as to make 
the distinction one which is b~ definition 
exhaustive. This last innovat~on str~kes me 
as an advantage, but others may not see the 
matter this way. 

On the standard notion of inductive argu-
ments as all those based on anyth~ng less 
than logical entailment as a connection be-
tween premises and conclusion, the argument 
'you should meet me at 2:00 because you prom-
ised to do so' would be inductive. 5 Yet such 
an argument seems to have nothing of impor-
tance in common with 'these observed crows 
were all black; so all crows are black'. The 
moral argument is of the type Wellman has 
termed 'conductive'. The conductive argument, 
he says: 

derives its conclusion from a variety 
of premises each of which has some 
independent relevance. TypicaIIY; 
although by no means always, several 
reasons are given in such arguments; 
and in those cases where a single 
reason is advanced, there are others 
which might have been given as well. 
Since what is characteristic of this 
sort of reasoning is the leading to-
gether of various considerations, it 
seems appropriate to label it "con-
duction". (page 52) [my emphasis) 

This type of reasoning has also been noticed 
by !1ichael Scriven and Stephen Thomas who, 
like Wellman, emphasize that premises bear 
separatel1 on the conclusion in such a way that the alsity of one does not affect the 
pertinence of others. 6 

12 
In conductive arguments, typically several 

factors relevant to the conclusion are cited 
in the premises, and the conclusion is then 
drawn, Examples: 

1. "You ought to take your son to the 
movie because you promised to do so, it 
is a good movie, and you have nothing 
better to do this afternoon." (Wellman, 
page 56) 

2. "This is not a good book because it 
fails to hold one's interest, is full of 
vague descriptions, and has a very 
implausible plot." (Wellman, page 56) 

3. "Hume is not a sceptic, for although he 
argues that our basic beliefs are not 
rationally justified, he rails against 
classical sceptics, and maintains that we 
are as much determined to believe as we 
are to think and feel." (My example) 

4. "We can be proud that America has 
turned the corner on the depression of 
the last few years. At last the many 
indexes of recovery are showing optimistic 
readings. The rate of inflation has 
slowed, unemployment has more or less 
stabilized, inventories are beginning to 
drop, advance orders are starting to pick 
up, and--the best news of all-the average 
income figures are showing a gain. The 
doomsayers have been discomfited, and the 
free enterprise system once more vindi-
cated," (Scriven, Reasoning, page 78) 

Wellman has a tendency to concentrate on ex-
amples which he has contrived and which are 
solely from the domain of moral arguments. 
In doing this, I think he does his own case 
an injustice, and it is for this reason that 
I've included other examples above. Wellman 
wishes to make the case that conductive argu-
ments are legitimate arguments which can 
serve to justify claims, and that where these 
arguments are used in support of moral judg-
ments, they deserve to be taken seriously as 
rational instruments. Since his ultimate 
interest is in meta-ethics, it is natural for 
him to concentrate on moral arguments; how-
ever, he would make a more solid case by 
showing that conductive reasoning and con-
ductive arguments are widely used, and in-
sisting that they are as legitimate in moral 
reasoning as elsewhere.' 

The conductive argument is one in which the 
premise, or premises, are each separately rel-
evant to the conclusion, though none is suf-
ficient to show its truth. In example (2) 
above, three quite separate reasons are 
given for thinking a book to be a poor one, 
Each aspect cited would be such as to make 
the book poor (i.e. relevant to thinking it 
poor), even in the absence of the other two, 
The three cumulate, so that good reason is 
given to think the book a poor one. In ex-
ample (3), one factor is cited which would 
count towards Hume being a sceptic, and two 
others which would count against that. The 
latter two are supposed to outweigh the first 
one so that the argument overall presents 
good reason to believe that Hume is not a 
sceptic, The key notion for the conductive 
argument seems to be that of relevance, that 
kind of relevance which is less than full 
entailment. In support of a conclusion many 
relevant factors can be brought forward, some 

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clusion it is most reasonable to accept. A 
conductive argument may be the product of 
such reasoning; this kind of argument will 
involve the specification of several such 
factors and adduce a conclusion on the basis 
of their cumulative force. S 

There are many conductive arguments among 
real life arguments. Their prevalence may 
help to explain several student assumptions 
which appeared to me at first to be peculiar 
and funny, and which are inappropriate as 
applied to classically deductive and induc-
tive arguments. Students, I've found, often 
believe that the more premises an argument 
has, the better it is. They find it almost 
impossible to believe, often, that an argu-
ment with only one premise could be a good 
argument. (If an argument has more premises, 
such students will insist, then it offers 
more reasons for its conclusion.) This line 
of thinking is appropriate for conductive 
arguments. Also, some students show a strong 
inclination to analyze arguments by setting 
out the premises and the conclusion and then 
proceeding to criticize connections as though 
each premise, separately considered, was 
supposed to lead to the conclusion. This 
critical strategy is often wholly wrong, but 
would be more or less appropriate for con-
ductive arguments. 

l-1ellman admits that since relevance is a 
content-dependent notion, there is little, if 
anything, of a formal or even a general na-
ture which can be said about conductive argu-
ments. Thev exist and they may be assessed 
(by 'thinking them through again'), though 
not formally. Wellman has a close discussion 
of the view--fairly common among philosophers 
--that validity must be formal and must be 
demonstrable by the application of formal 
rules of inference. He rejects this view for 
various reasons, most importantly because 
formal rules must derive from and be testable 
~y, nonformal, extra-systematic judgments of 
validity. 

surely the existence of valid reasoning 
does not presuppose the existence of 
any such calculus of derivation rules, 
for the inferences formalized by 
Hilbert and Ackerman, say, were valid 
before they invented their logical 
system just as the syllogism was 
valid long before Aristotle. As a 
rule, the logician tries to construct 
his calculus so that it will reflect 
some sort of reasoning that is 
recognized to be valid independently 
of his system. To be sure, the in-
ventive logician can think up queer 
logics which suggest new, and some-
times strange, ways of reasoning. 
But if these queer logics become too 
queer, they are no longer considered 
logics, but only symbolic games of 
some similar sort. This indicates 
that even here, our standards of 
validity are outside of and independent 
of the derivation rules in any 
uninterpreted calculus. (page 75)9 

This point, strongly emphasized by such 
theorists of logic as Arthur Pap and Susan 

13 
Haack, seems to me to be entirely correct. 
Connections which exist between premises and 
conclusions are not the products of logical 
systems, but rather are presupposed by those 
systems. Validity is not by definition for-
mal validity; connections need not be formal-
ly articulable in order to exist. There is 
room, then, for the idea of a legitimate 
connection between the premises and con-
clusion of conductive arguments, even though 
this connection is most unlikely to be for-
mally capturable. Though it may be true, as 
Wellman anticipates it will be, that there is 
little of a systematic nature which can be 
said about conductive arguments, that is no 
reason to deny their existence, or to deny 
them any sort of validity. 

I"ellman's innovation on 'inductive I and his 
defense of the notion of conductive argument 
strike me as the most significant aspects of 
his book for those interested in informal 
logic and, accordingly, I have described 
these at some length. There is much else 
that is pertinent and for other topics I 
shall be considerably more brief. 

There is the matter of validity. \'l'ellman 
eventually develops an umbrella notion of 
validity which applies to arguments of all 
types: 

If it is granted that inductive and 
conductive arguments cannot be re-
duced to deductive form and that 
they are subject to logical criticism, 
then it must be admitted that there is 
a genuine sense in which thes7 arguments 
are valid or invalid. By log~cal 
criticism I mean the judgment of correct-
ness or incorrectness as inferences, 
as drawing a conclusion from one or 
more premises, quite apart from a~y 
question of the truth of the prem~ses. 
Once deductivism is abandoned, the 
need for this broader conception of 
validity becomes apparent. (page 240) 

His proposal for 'valid' is: to ~ay.that an 
argument is valid is to say that ~t ~s per-
suasive after indefinite criticism for all 
those who think in the normal way. 'Indefi-
nite' criticism is required so that the notion 
of validity is not purely descriptive; 'the 
normal way' so that the failure of an argu-
ment to convince lunatics does not brand it 
invalid. Thinking in the normal way means 
"having a tendency to be persuaded by some 
sort of arguments and not by other sorts 
• • • most men are similarly persuaded or 
unpersuaded". There seem to be dangers of 
circularity here. 

Wellman also seems to be in some trouble 
with the question of whether an argument with 
false or unwarranted premises can be valid in 
his sense--can it be persuasive? 

What are the conditions of persuading? 
That the person to be persuaded 
accepts or has the premises of the 
argument, that he rejects or doubts 
it conclusion, and that he pays 

attention to or thinking through 
the argument. • . • . . to say that 
an argument is persuasive is to say 
that is usually persuades one who 
accepts or has its premises, who 
rejected or doubted its conclusion 



just before being subjected to the 
argument, and who thinks through 
the argument. (page 91) 

What about one who rejects the premises of an 
argument? Can the argument be persuasive to 
him? It must be found 'persuasive after in-
definite criticism' to qualify as valid in 
the new sense. Yet since the account of per-
suasiveness is in terms of one who accepts 
the premises, it is hard to see how Wellman 
can achieve what he wants, namely an umbrella 
way of speaking of the connection between 
premises and conclusions which is independent 
of considerations of the truth or falsity of 
premises. He tries to fix the account, 
saying: 

a pe:son who does not accept the 
prem~ses of a given argument can 
still imagine what it would be like 
to accept them and make a good guess 
as to whether they would then persuade 
one of the conclusion. (page 109) 

I am not sure this is good enough. 

A more fundamental question is whether such 
an umbrella notion of validity, involving as 
it does a fundamental departure from tradi-
tion in logic, is desirable. S. N. Thomas, 
in his text, takes the position that 'valid-
ity' applies to arguments of all types and 
is a matter of degree. So Wellman isn't the 
only one suggesting radical changes. Person-
ally I'm not sure I favor innovations here, 
as deductive validity is an established and 
relatively clear concept. Perhaps some new 
term could be adopted to handle the 'umbrella' 
aspect, and then deductive validity would be 
a species of this connectedness of premises 
and conclusion. Wellman points out that the 
ordinary language use of 'valid' is broader 
than the logicians', and this seems to be 
true--however the ordinary language use is so 
broad as to move towards considerations of 
truth as well. (E.g. "that's a valid point 
you made .•. ") 

Another key topic discussed by Wellman is 
the matter of missing premises. This problem 
is not discussed in any general way; however 
Wellman becomes involved in it when introduc-
ing his notion of a conductive argument. He 
is aware that, given a move from a particular 
premise to a particular conclusion, many will 
insist that the argument must be enthymematic, 
so that there is a general premise missing. 
Descartes ran into this problem when some 
critics insisted that 'I think therefore I 
am' was really a syllogism requiring as a 
missing premise 'everything that thinks 
exists.'lO Descartes denied it; Wellman does 
too. 

Consider the simple conductive argument: 
'you should return the book, because you 
promised you would do so'. Someone might in-
sist that this argument is enthymematic, 
requiring a missing premise--e.g. 'People 
should do everything they promise to do'. 
Such insistence turns conductive arguments 
into deductive ones and makes reasoning about 
particular instances dependent upon the ac-
ceptance of general principles. Wellman 
strongly resists the move, saying that the 
universal premise inserted is almost always 
false, or at any rate less plausible than the 
particular inference which the arguer wants 

14 

to draw, and that it is not fair interpreta-
tion to saddle people with general claims 
when all they have set out to do is to draw 
particular inferences. We often want to do 
this, but perhaps this is only .because we are 
so strongly inclined, by training, to look at 
arguments through deductivist goggles. 

Turning conductive arguments into deductive 
ones grossly distorts their meaning and 
structure, for deductive arguments are sup-
posed to be conclusive. A conductive argu-
ment, citing three factors relevant to the 
establishment of a conclusion, would turn in-
to three deductive arguments, each of which, 
as conclusive, would render the other two 
entirely redundant. This point seems to me 
to be an important one, and one which would 
apply to much philosophical argumentation. 
(If proponents of (e.g.) the mind/brain 
identity theory really think that their argu-
ments for the theory are deductive, why would 
they need more than one?ll) 

A fault which runs throughout Wellman's ac-
count is the failure to distinguish between 
reasoning and arguments. Despite his general 
carefulness, Nellman seems to make this re-
lationship too close, identifying reasoning 
with putting forward or following through one 
or more arguments. But there is the process 
of argument construction, where one sifts 
through evidence, tries to determine what is 
relevant and what isn't •.. and all of 
this, which precedes the expression of an 
argument, is on most accounts recognized as 
reasoning. I don't think there is any cru-
cial problem here, and I've simply tried to 
use 'araument' in contexts where Wellman 
speaks of reasoning, but is pretty clearly 
dealing with the arguments that are the 
product of reasoning. The point is of some 
importance, however, for critics might be 
tempted to allow that such reasoning is con-
ductive, but deny that there is such a thing 
as conductive argument. I don't think this 
criticism is very plausible, in the light of 
the many examples of conductive arguments 
which can easily be found in natural language. 

The book covers much which I've not dis-
cussed. I shall finish where I began, by 
urging others interested in informal logic 
to study this rich source, 

1. 

2. 

3. 

Footnotes 

In the last issue of Informal Logic ~­
letter, (November, 1979). 
This passage exemplified Wellman's ten-
dency to very closely relate reasoning 
and argument. As he is clearly talking 
about kinds of argument in this context, 
I.ve dealt with these and not with the 
question (much broader) of what different 
kinds of reasoning there might be. 

There is a connection here with the con-
cept of reflective equilibrium, made 
fashionable by Rawls. Many moral philos-
ophers now accept what Wellman refers to 
as induction in morals, though they would 
add that views on particular cases may 

.also be revised by theoretical principles 
which are in some sense or other well-
established. The analogy which Wellman 
wishes to draw between ethical and sci-
entific reasoning also seems to be quite 
a widely accepted one in current moral 

4. 

5. 

6. 

7. 

8. 

9. 

10. 

11. 

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llman 
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quite 

oral 

philosophy. (Note: this is not a fal-
lacious appeal to authority, but merely a 
point of information!) 

4. Adapted from an argument in the Toronto 
Globe and Mail, appearing sometime in 
JaiiiJarY";-l9'8'Q, 

5. That is, unless we insist on adding as a 
missing premise, 'You should do every.,. 
thing you promise to do', in which case 
the arqument is deductive. 

6. See Scriven, Reasoning, pages 78-81, and 
Thomas, Practical Reasoning in Natural 
Language, pages 37-40. 

7. He does note that the concept of conduc-
tive argument has wider application, say-
ing, "~'Jherever some descriptive predicate 
is ascribed on the basis of a family re-
semblance, conductive reasoning takes 
place." (page 54). But he does not make 
enough of this point, nor does he tell us 
how many descriptive predicates ~ as-
cribed on the basis of family resemblance. 
(If most are, as Wittgenstein seems to 
have thought, then conductive reasoning 
would be very common, and conductive ar-
guments an extremely important type. 
Compare D. C. Yalden-Thomson, "The 
Virginia Lectures", in Wisdom: Twelve 
Essays, edited by Renford Bambrough.) 

8. Wellman specifies three different patterns 
of conductive argument; one where only 
one relevant factor is adduced; one where 
several are adduced; and a third where 
both 'pro' and 'con' factors are adduced, 
and the claim is made that the former out-
weigh the latter. 

9. Compare Susan Haack, Philosophy of Logics, 
Chapter II. 

10. See Objections to the Meditations (II), 
and Descartes' reply, in which he insists 
that a general proposition is not re-
quired and that, indeed, "general pro-
positions are formed out of the knowledge 
of particulars" (page 38, Volume II, in 
Haldane and Ross edition.) A similar 
response is made by Descartes in a letter 
to Clerselier (page 127 in Haldane and 
Ross, II.) 

11. Compare Francis Dauer, "The Diagnosis of 
an Argument", r1etaphilosophy, 1974. 

15 

UI\EJERS I ~CING 
SCIENTIFIC 
REASONING 
Ronald N. Giere 

William Berriman 
University of Regina 

Suppose one could gather together about a 
hundred university professors of philosophy 
and suppose furthermore that they represented 
a fair sample of today's philosophers with 
respect to contemporary thinking about the 
teaching of logic and philosophy. To these 
people one now reads the first four para-
graphs of Giere's Preface. 

By the end of the reading the philosophers 
would have become decisively divided on their 
attitudes to the book. Giere speaks of "new 
courses in 'applied philosophy''', of the 
"students' demand for 'relevance'" and of his 
reluctant rejection of his idea of subtitling 
the book "A Consumer's Guide to Scientific 
Method". He claims that students can become 
intelligent consumers of scientific informa-
tion not by learn~ng science (or in his words 
"how to be scientists") but by learning 

merely how to read and interpret 
reports of scientific findings, 
espec~ally reports that appear in 
the popular magazines, newspapers, 
and even supermarket tabloids. 

Some of our philosophers would denounce the 
book as "light weight", "not academically 
respectable" and condemn the book outright. 
The others would find that the book arouses 
their interest. This aroused interest may 
have three (possibly overlapping) sources: 
a) an awareness of the possibility that the 
book may form the basis of an attractive 
(pop?) class. b) On the basis of one's know-
ledge of today's students plus the nature of 
many media reports one may have concluded i) 
that most people know very little about 
science but that ii) they are prepared to 
believe the most outrageous stories provided 
these are in the realm of "science". Finally 
c) Giere's book appears to offer the oppor-
tunity to extend one's work in informal logic 
into the area of the logic of science, and 
reports about science in the media. 

A cursory glance through the book reveals 
material that should arouse student interest. 
Giere's chapters deal with Haley's long-
range forecast of the appearance of his comet, 
the World II model which uses a computer to 
predict disaster for mankind by the year 2100 
unless great changes are made in the world 
socio-economic system by 1985. Additional 
(to informal logic) fallacies such as Vague 
Predictions (or the Delphi Fallacy), The Jean 
Dixon Fallacy (multiple predictions),