erful for discipline; any or all of which may be present,
and sufficient to explain both the luxury and the ruin.

(6) To mistake one condition of a phenomenon for the whole cause. To
speak of an indispensable condition of any phenomenon as the cause of
it, may be a mere conventional abbreviation; and in this way such a mode
of expression is common not only in popular but also in scientific
discussion. Thus we say that a temperature of 33 deg. F. is a cause of the
melting of ice; although that ice melts at 33 deg. F., must further depend
upon something in the nature of water; for every solid has its own
melting-point. As long, then, as we remember that 'cause,' used in this
sense, is only a convenient abbreviation, no harm is done; but, if we
forget it, fallacy may result: as when a man says that the cause of a
financial crisis was the raising of the rate of discount, neglecting the
other conditions of the market; whereas, in some circumstances, a rise
of the Bank-rate may increase public confidence and prevent a crisis.

We have seen that the direct use of the Canons of Agreement and
Difference may only enable us to say that a certain antecedent is a
cause or an indispensable condition of the phenomenon under
investigation. If, therefore, it is important to find the whole cause,
we must either experiment directly upon the other conditions, or resort
to the Method of Residues and deductive reasoning; nor must we be
content, without showing (where such precision is possible) that the
alleged cause and the given phenomenon are equal.

(7) To mistake a single consequence of a given cause for the whole
effect, is a corresponding error; and none so common. Nearly all the
mistakes of private conduct and of legislation are due to it: To cure
temporary lassitude by a stimulant, and so derange the liver; to
establish a new industry by protective duties, and thereby impoverish
the rest of the country; to gag the press, and so drive the discontented
into conspiracy; to build an alms-house, and thereby attract paupers
into the parish, raise the rates, and discourage industry.

(8) To demand greater exactness in the estimate of causes or effects
than a given subject admits of. In the more complex sciences, Biology,
Psychology, Sociology, it is often impossible to be confident that all
the conditions of a given phenomenon have been assigned, or that all its
consequences have been traced. The causes of the origin of species and
of