Premise and Conclusion Analysis Drill
For each stimulus, identify the conclusion(s) and supporting premise(s), if any. The answer key will
identify the conclusion and premises of each argument, the logical validity of each argument, and also
comment on how to identify argument structure. Each stimulus comes from a real LSAT question.
Answers on Page 38
1. Every year, new reports appear concerning the health
risks posed by certain substances, such as coffee and
sugar. One year an article claimed that coffee is
dangerous to one’s health. The next year, another article
argued that coffee has some benefits for one’s health.
From these contradictory opinions, we see that experts are
useless for guiding one’s decisions about one’s health.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
2. Some teachers claim that students would not learn
curricular content without the incentive of grades. But
students with intense interest in the material would learn
it without this incentive, while the behavior of students
lacking all interest in the material is unaffected by such an
incentive. The incentive of grades, therefore, serves no
essential academic purpose.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
3. Damming the Merv River would provide irrigation for the
dry land in its upstream areas; unfortunately, a dam would
reduce agricultural productivity in the fertile land
downstream by reducing the availability and quality of
water there. The productivity loss in the downstream area
would be greater than the productivity gain upstream, so
building a dam would yield no overall gain in agricultural
productivity in the region as a whole.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
4. In a study, infant monkeys given a choice between two
surrogate mothers—a bare wire structure equipped with a
milk bottle, or a soft, suede-covered wire structure
equipped with a milk bottle—unhesitatingly chose the
latter. When given a choice between a bare wire structure
equipped with a milk bottle and a soft, suede-covered
wire structure lacking a milk bottle, they unhesitatingly
chose the former.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
5. While it was once believed that the sort of psychotherapy
appropriate for the treatment of neuroses caused by
environmental factors is also appropriate for
schizophrenia and other psychoses, it is now known that
these latter, more serious forms of mental disturbance are
best treated by biochemical—that is, medicinal—means.
This is conclusive evidence that psychoses, unlike
neuroses, have nothing to do with environmental factors
but rather are caused by some sort of purely organic
condition, such as abnormal brain chemistry or brain
malformations.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
6. If relativity theory is correct, no object can travel forward
in time at a speed greater than the speed of light. Yet
quantum mechanics predicts that the tachyon, a
hypothetical subatomic particle, travels faster than light.
Thus, if relativity theory is correct, either quantum
mechanics’ prediction about tachyons is erroneous or
tachyons travel backwards in time.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
7. Any course that teaches students how to write is one that
will serve them well later in life. Therefore, since some
philosophy courses teach students how to write, any
student, whatever his or her major, will be served well in
later life by taking any philosophy course.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
6. If relativity theory is correct, no object can travel forward
in time at a speed greater than the speed of light. Yet
quantum mechanics predicts that the tachyon, a
hypothetical subatomic particle, travels faster than light.
Thus, if relativity theory is correct, either quantum
mechanics’ prediction about tachyons is erroneous or
tachyons travel backwards in time.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
7. Any course that teaches students how to write is one that
will serve them well later in life. Therefore, since some
philosophy courses teach students how to write, any
student, whatever his or her major, will be served well in
later life by taking any philosophy course.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
For each stimulus, identify the conclusion(s) and supporting premise(s), if any. The answer key will
identify the conclusion and premises of each argument, the logical validity of each argument, and also
comment on how to identify argument structure. Each stimulus comes from a real LSAT question.
Answers on Page 38
1. Every year, new reports appear concerning the health
risks posed by certain substances, such as coffee and
sugar. One year an article claimed that coffee is
dangerous to one’s health. The next year, another article
argued that coffee has some benefits for one’s health.
From these contradictory opinions, we see that experts are
useless for guiding one’s decisions about one’s health.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
2. Some teachers claim that students would not learn
curricular content without the incentive of grades. But
students with intense interest in the material would learn
it without this incentive, while the behavior of students
lacking all interest in the material is unaffected by such an
incentive. The incentive of grades, therefore, serves no
essential academic purpose.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
3. Damming the Merv River would provide irrigation for the
dry land in its upstream areas; unfortunately, a dam would
reduce agricultural productivity in the fertile land
downstream by reducing the availability and quality of
water there. The productivity loss in the downstream area
would be greater than the productivity gain upstream, so
building a dam would yield no overall gain in agricultural
productivity in the region as a whole.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
4. In a study, infant monkeys given a choice between two
surrogate mothers—a bare wire structure equipped with a
milk bottle, or a soft, suede-covered wire structure
equipped with a milk bottle—unhesitatingly chose the
latter. When given a choice between a bare wire structure
equipped with a milk bottle and a soft, suede-covered
wire structure lacking a milk bottle, they unhesitatingly
chose the former.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
5. While it was once believed that the sort of psychotherapy
appropriate for the treatment of neuroses caused by
environmental factors is also appropriate for
schizophrenia and other psychoses, it is now known that
these latter, more serious forms of mental disturbance are
best treated by biochemical—that is, medicinal—means.
This is conclusive evidence that psychoses, unlike
neuroses, have nothing to do with environmental factors
but rather are caused by some sort of purely organic
condition, such as abnormal brain chemistry or brain
malformations.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
6. If relativity theory is correct, no object can travel forward
in time at a speed greater than the speed of light. Yet
quantum mechanics predicts that the tachyon, a
hypothetical subatomic particle, travels faster than light.
Thus, if relativity theory is correct, either quantum
mechanics’ prediction about tachyons is erroneous or
tachyons travel backwards in time.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
7. Any course that teaches students how to write is one that
will serve them well later in life. Therefore, since some
philosophy courses teach students how to write, any
student, whatever his or her major, will be served well in
later life by taking any philosophy course.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
6. If relativity theory is correct, no object can travel forward
in time at a speed greater than the speed of light. Yet
quantum mechanics predicts that the tachyon, a
hypothetical subatomic particle, travels faster than light.
Thus, if relativity theory is correct, either quantum
mechanics’ prediction about tachyons is erroneous or
tachyons travel backwards in time.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
7. Any course that teaches students how to write is one that
will serve them well later in life. Therefore, since some
philosophy courses teach students how to write, any
student, whatever his or her major, will be served well in
later life by taking any philosophy course.
A. What is the conclusion of the argument, if any?
B. What premises are given in support of this conclusion?
C. Is the argument strong or weak? If you think that the argument is weak, please explain why.
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