Almost every discussion of technical or scientific
style mentions the passive voice, usually as a stylistic evil to avoid.
While I doubt that many of us would endorse such extreme prescriptions
as "Always use the active voice," 1 or "A
writer will almost automatically improve his style when he shifts from
passive to active constructions,"2 we may be more ready
to accept Freedman's position in "The Seven Sins of Technical Writing."
His Sin 6 is "the Deadly Passive, or, better, deadening
passive; it takes the life out of writing, making everything impersonal,
eternal, remote and dead,"3 but he adds that "frequently,
of course, the passive is not a sin and not deadly, for there simply
is no active agent and the material must be put impersonally."4
From these two statements one would have to conclude that the legitimate
use of the passive voice is restricted to situations where there is
no "active agent." But is this conclusion correct? I think
we can agree that the passive voice does have legitimate uses in technical
and scientific writing and also that it is frequently misused. The problem
is to define the appropriate or effective uses and the inappropriate
or ineffective ones. In trying to solve this problem, I examined the
use of the passive voice in six articles, three in Scientific American
and three in more specialized journals. 5 On the basis of
this very limited sample, I have selected five kinds of passive structures
for further discussion here. Since I believe that the bias of the technical
writing teacher is toward avoiding the passive voice, I have concentrated
on the arguments that support the use of each of these five structures.
The minimal distinction that must be drawn in discussing passive structures
is between what is called the full passive and what is called the truncated
passive. 6 The full passive, sentence 1, includes an agentive
adjunct,7 whereas the truncated passive, sentence 2, does
not:
1. The ball was kicked by Bill.
2. The ball was kicked.
As a result, different arguments must be used to support or discourage
the use of these two major kinds of passives. First, since the agent
is specified in the full passive, the subject for an active voice equivalent
is always available, so that sentence 1 can be replaced by sentence
3:
3. Bill kicked the ball.
On the other hand, if a truncated passive is to be replaced by an active
clause, a subject must be supplied for the active clause, and there
is considerable variation in how straightforward or desirable this is.
Second, only the full passive is longer than the equivalent active,
and this means that the argument that the passive "squanders words"8
applies only to the full passive. The important similarity among all
passives is that the recipient of the action, not the agent, is the
subject. Whether or not this is a desirable feature depends on the discourse
context of the passive structure under consideration, and on the nature
of the statement the passive structure makes.
Although textbooks often discuss only the full passive, the full passive
is rather rare in scientific writing, and in English prose generally.
In four of the articles I examined, fewer than ten percent of the passives
were full passives, and in the other two articles, only twenty percent
and twenty-seven percent of the passives were full. In other words,
more than seventy percent of the passive structures in any of these
articles were truncated, and this statistic is perhaps supported by
Jespersen's claim that "over 70 percent of passive sentences found
in English literature contain no mention of the active subject."9
It may be interesting to note also that English is in fact unusual in
having a full passive; most languages that have a passive voice have
only the truncated passive. 10
What, then, are the arguments for using the full passive instead of
the active? First, as Jane Walpole and others have pointed out, the
full passive may allow theme to be maintained in the discourse. 11 What
this means, briefly, is that the subject of the sentence is usually
interpreted as the theme, or what is being talked about. 12 If the agent
is not the theme, then the full passive allows the writer to remove
it from the subject position. In part then, the choice between the full
passive and the active is constrained by the discourse context of the
particular clause. One fairly common use of the full passive is in the
acknowledgement of the scientist responsible for a discovery, as in
sentence 4:
4. Solions for " solution of ions" utilizing
a reversible redox electrochemical system, were first proposed and studied
by Elihu Root, III, at the U.S. Naval Ordnance Laboratory, now at Silver
Spring, Md. 13
Sentence 4 is the opening sentence in an article about solions; the
active equivalent would have suggested that the article would be about
Root. The use of the full passive to maintain theme is also shown in
sentence 5:
5. The X-ray map of Cassiopeia A we have made, together
with a spectrum of the remnant plotted from the same data, suggest that
the X-rays are radiated not by some central source but by hot gas produced
by shock waves from the original explosion traveling through the interstellar
medium. 14
Clearly, X-rays is the theme. Furthermore, in this case the
subject of the equivalent active clause is so complex linguistically
that the active would be clumsy at least: 15
5a. ... suggest that not some central source but hot
gas produced by shock waves from the original explosion traveling through
the interstellar medium radiates the X-rays.
Generally, then, we can argue that the full passive is a useful alternative
to the active if the subject of the passive, and not the agent, is the
theme of the discourse segment, or if the agent is so complex linguistically
that its placement in subject position could lead to a perceptually
more difficult sentence.
It is much more difficult to generalize about the truncated passive.
Here I have limited my discussion to truncated passives used in the
following four kinds of scientific discourse segments:
A. descriptions of experimental procedures
B. descriptions of standard procedures
C. descriptions of the state of knowledge
D. descriptions of natural processes.
These passives differ in the kind of subject their corresponding active
clauses could have, if any.
The truncated passive used in descriptions of experimental procedures
is almost synonymous in many people's minds with "the scientific
style," and has probably received most attention in discussions
of scientific style. What differentiates it most clearly from the other
truncated passives I will discuss is the fact that the choice between
it and an active clause is structurally unrestricted; it can easily
be replaced by an active clause whose subject usually is I or we. For
example, passage 6 can be replaced by passage 6a:
6. One sample was dissolved prior to thermal treatment.
At 30 min. intervals, samples were withdrawn and dissolved in carrier
solutions, and the temperature of the bath was increased by approx.
5°C.16
6a. We dissolved one sample prior to thermal treatment.
At 30 min. intervals, we withdrew samples and dissolved them in carrier
solutions, and we increased the temperature of the bath by approx. 5°C.
In practice, of course, I doubt that many writers exercise a conscious
choice, for the truncated passive has become traditional. Tradition
aside, however, the main argument that supports this use of the truncated
passive is that it allows theme maintenance, for surely the discourse
is not about the agent, but rather about the procedure. The counter-argument
that the truncated passive obscures the identity of the agent is not
valid in this case, it seems to me, for the agent is fully recoverable
from the context. We assume that the agent is the author(s) or the author’s
assistants, who allow him to perform the experiment by proxy. Another
counter-argument is that this use of the passive leads to monotonous
prose. However, the active equivalent would probably be just as monotonous,
since every sentence would have to repeat the agent in subject position.
Also, at least in scientific articles, monotony is probably not a serious
fault for procedural descriptions are never read for entertainment if
they are read at all the descriptions simply qualify the results.
A related but somewhat different use of the truncated passive is shown
in passage 7:
7. To measure the number of gene copies the cellular
DNA is broken into small pieces, the double strands are denatured (separated
into single strands) by boiling, and a small amount of the radioactively
labeled complementary DNA is added to the mixture under experimental
conditions in which the complementary DNA can now hybridize with any
DNA with which it has complementary nucleotide sequences. 17
Whereas passage 6 describes a particular procedure, passage 7 describes
a standard procedure; descriptions of particular procedures use the
past tense, while descriptions of standard procedures use the present
tense. Supplying a subject for an active equivalent is still not difficult;
some choices are one, a person, or we. Thus, passage
7 could be replaced by passage 7a:
7a. To measure the number of gene copies, one breaks
the cellular DNA into small pieces . . .
However, since the active subject has to be general or indefinite,
the active clauses are no more informative than the truncated passives,
and the criticism that the passive obscures the identity of the agent
clearly does not apply. In fact this use of the truncated passive allows
a writer to sidestep the issue of non-sexist language; as Mills and
Walter have pointed out, "the active voice has in recent years
become somewhat impractical because of distaste for the use of masculine
pronouns . .. in situations in which the referent may be either male
or female."18
A truncated passive may also be used to describe the state of scientific
knowledge. Consider, for example, passage 8:
8. The mechanics of isolating vibration are well understood,
and the necessary physical properties of the isolators have also been
determined. 19
The two clauses present slightly different problems. It is difficult
to supply an appropriate subject for an active equivalent of the first
clause, for someone is probably too vague and narrow, the general
we may be confused with the particular we if the paper has more than
one author, and scientists or people is probably too broad.
It seems to me that statements like those in passage 8 presuppose an
abstract agent that represents our sense of a communal repository of
knowledge, and the truncated passive allows us to avoid having to define
this abstraction more concretely. In the second clause, however, in
addition to the abstract agent, there are also, ultimately, specific
agents who determined the physical properties of the isolators. Whether
or not these specific agents should be named depends in part on the
purpose and audience of the discourse. Sentence 8 appears in Scientific
American and the purpose is to provide fairly general information.
If the same statement were presented for a more expert audience, documentation
conventions would probably be used to identify the agents. This general
category of truncated passives also differs from the previous ones in
that the verbs are restricted to a rather small class.
Finally, the truncated passive is used to describe processes in which
there is no direct human agency, as in sentence 9:
9. If the pulsar is embedded in a nebula, the electrons
are presumably hurled into the nebula and spiral along its own magnetic
lines of force, emitting radiation over an enormous range of wave lengths.
20
Often it is very difficult to supply an accurate subject for an active
clause equivalent in these cases, for the only legitimate choice may
be something like "natural forces." In fact, in trying to
supply such a subject, one could very easily distort scientific facts.
In conclusion, then, the main fault of many prescriptions about the
use of the passive voice is that they are over-generalizations. For
example: "The passive voice is weak and colorless. It is also wordier
than the active voice, and tends to hedge. Nevertheless, it is often
used in technical writing because it promotes impersonality and restraint.
. ."21 While there is, of course, the passive
voice, there isn't the passive clause, but rather a number
of different kinds of passive clauses, so that a statement that applies
to one kind does not necessarily apply to the other kinds. It is necessary,
first of all, to distinguish between the full passive and the truncated
passive. The argument that the passive is wordy can only apply to the
full passive, and the argument that the agent is obscured can only apply
to some truncated passives. Within the category of truncated passive,
further distinctions can be made on the basis of the kinds of subjects,
if any, that could be supplied for active clause equivalents. As we
have seen in this fragmentary examination, there are truncated passives
for which it is impossible to supply active clause subjects, ones whose
active clause subjects are abstract, ones whose active clause subjects
are general and indefinite, and ones whose active clause subjects are
directly recoverable from the discourse context. These different kinds
of truncated passives are also used in different kinds of statements
commonly found in scientific prose.
1 Peter Burton Ross, Basic Technical Writing (New
York Thomas Y. Crowell, 1974), P. 210.
2 Donald H. Menzel, Howard Mumford Jones, and Lyle G. Boyd,
Writing a Technical Paper (New York: McGraw-hill, 1961), p. 81.
3 Morris Freedman, “The Seven Sins of Technical Writing,”
CCC, 9 (1958), 14.
4 Freedman, 14.
5 Theodore P. Yin, “The Control of Vibration and Noise,”
SA, 220 No. 1 (Jan. 1969), 98-106.Robert I. Schimke, “Gene Amplification
and Drug Resistance,” SA, 243, No. S (Nov. 1980), 60-69.Philip
A. Charles and J. Leonard Culhand, “X Rays from Supernova Remnants,”
SA, 233, No. 6 (Dec. 1975), 38-46.Nelson N. Estes, “Solions,
Their Characteristics and Commercial Applications,” IEEE Transactions
on Industrial Electronics, 10, No. 1 (May 1963), 91-100.John L.
Bronte and Don S. Martin, “Szilard-Chalmers and Thermal Annealing Processes
in D- Tris (Ethylenediamine) Cobalt (III) Nitrate,” Journal
of lnorganic Nuclear Chemistry, 39 (1977), 1481-1486. Neville F.
Alley and Steven C. Chatwin, “Late Pleistocene History and Geomorphology,
Southern Vancouver Island, British Columbia,” Canadian Journal of
Earth Sciences, 16, No. 9 (Sept. 1979), 1645-1657.
6 RobertFreidin, “The Analysis of Passives,” Language,
51 No.2(1975), 384-405.
7 John Lyons, Introduction to Theoretical Linguistics
(Cambridge: Cambridge Univ. Press, 1968), P. 378.
8 Kenneth W. Houp and Thomas E. Pearsall, Reporting Technical
Information , 3rd ed. (Encino, Ca: Glencoe, 1977), p. 138
9 Otto Jespersen, Essentials of English Grammar (London:
Allen and Unwin, 1933), p. 121.
10 Lyons, p. 378.
11 Jane R. Walpole, “Why Must the Passive Be Damned?” CCC,
30 (Oct. 1979), 251-254.
12 See John Lyons, Semantics, II (Cambridge: Cambridge
Univ. Press, 1977), pp. 500-511; M.A.K. Halliday and Ruquaiya Hasan,
Cohesion in English (London: Longman, 1976); Rodney D. Huddleston,
The Sentence in Written English (Cambridge: Cambridge Univ. Press,
1971).
13 Estes, 91.
14 Charles and Culhane, 38.
15 F. R. Palmer notes this use of the full passive on P.
87 in The English Verb (London: Longman 1974).
16 Bonte and Martin, 1481-82.
17 Schimke, 63.
18 Gordon H. Mills and John A. Walter, Technical Writing,
4th ed. (New York: Holt, 1978), p. 133.
19 Yin, 101.
20 Charles and Culhane, 40.
21 Rufus P. Turner, Grammar Review for Technical Writers,
rev. ed. (San Francisco: Rinehart, 1971), p. 53.