Which two of the following are assumptions underlying the above argument?

Question

It is commonly agreed that climate change is the most serious environmental issue facing the modern world. Proponents of nuclear and hydrogen power appeal to the fact that these forms of energy production do not involve the burning of fossil fuels, and hence do not increase the levels of carbon dioxide in the atmosphere. Sceptics point out that, as well as being expensive, both nuclear and hydrogen power do in fact involve the burning of some fossil fuels: nuclear power requires uranium to be mined, refined and concentrated, and atomic hydrogen would have to be produced in large power plants using fossil fuel. Yet these objections should be discounted. No solution to a complex global issue is ever going to be perfect. In the absence of better alternatives, we must convert as much power generation as possible to nuclear and hydrogen cell methods.

Which two of the following are assumptions underlying the above argument?

A Cleaner methods of energy production than either nuclear or hydrogen power will not be discovered in the future.

B Global climate change is not too complex a phenomenon to be accurately measured.

C The production of hydrogen cells and nuclear power emits less carbon dioxide than conventional means.

D The increase in carbon dioxide levels in the atmosphere is a major cause of climate change.

E Uranium can only be mined using conventional means of fossil-fuel generated power production.

Answer 1

The correct answer is C  + D

Justification

The argument structure is as follows:

R1 Climate change is the most serious environmental issue facing the modern world.

R2 Nuclear & hydrogen power production do not involve the burning of fossil fuels, and hence do

not increase the levels of carbon dioxide in the atmosphere.

R3 (Counter assertion) Some fossil fuels are in fact required in pre-production of both nuclear and

hydrogen power.

R4 (Counter-Counter assertion) No solution … will ever be perfect.

Therefore (intermediate conclusion), these objections should be discounted.

Therefore (conclusion), in the absence of better alternatives, we must convert as much power

generation as possible to nuclear and hydrogen cell methods.

The only positive support for the conclusion is contained in R1 & R2 (R3, R4 and the intermediate

conclusion merely dismiss a possible counter-argument). Without the assumption that increased

carbon dioxide levels is a major cause of climate change, the conclusion cannot be drawn.

Candidates may be deterred from choosing it on the grounds that it is commonly taken to be a

fact rather than a theoretical causal link. Either way, it is unstated in the passage and therefore

an assumption.

D is also needed in order for the conclusion to follow. Without this assumption, and following the

logic of the argument’s own first two reasons, R3 would be a devastating objection, and the

conclusion would not follow.

Distractors

A. The argument is perfectly consistent with the notion that better solutions will perhaps arise. It

only concludes that ‘In the absence of better solutions…’ Therefore it does not rest on the

assumption that A is true.

B is a tempting distractor, but its truth or otherwise does not directly affect the reasoning in the

argument, which moves from the general acceptance of the real dangers of climate change to

one important way in which we should respond. The claim that climate change is too complex a

phenomenon to measure accurately could form the basis of a very different argument, but not

necessarily one leading to an alternative conclusion. It could be true that climate change is too

complex for us to measure accurately and yet still true, based on the reasons given in the

argument, that we should take the steps recommended. Hence the argument does not rest on its

being false (i.e. statement B).

If E is not true, then the argument would actually be strengthened; hence it is not an assumption

on which the argument rests. (It is also too close too the meaning of R3 to be an assumption by

the definition as provided in the subject specifications).

Answer 2

Why would we even mess with nuclear when we have better alternatives, which are 100% safe, 100% clean, and less expensive than nukes?

I'm speaking mostly of solar energy.

OK 100% clean once they are operating.  It will require power probably generated largely from fossil fuels to make the solar equipment, but in the long run that won't amount to much in the equation.

Here's what one solar thermal company says.

"Solar thermal power plants such as Ausra's generate electricity by driving steam turbines with sunshine. Ausra's solar concentrators boil water with focused sunlight, and produce electricity at prices directly competitive with gas- and coal-fired electric power."

And I'll post this again.

http://www.sciam.com/article.cfm?id=a-so...  How we can have 65% solar electric grid by 2050, near 100% by 2100  using less public money, 1/4 as much as we now give oil companies in subsidies.  And about 1/40 of the hidden costs of oil, which includes subsidies.

The cleaner methods are already here. so that doesn't support the argument for nukes in A.

As far as C goes, I don't know the cost analysis of producing fuel cells.   The real question is maybe how efficiently and cleanly hydrogen can be produced.

Answer 3

Well, reading it through, it seems like all of them underlie one of the two arguments being made.  But if it is the last sentence, I would say C is elemental to the argument as well as D (or possibly A, it is hard to be sure).

Answer 4

C and D

Answer 5

A, C and E?

Geothermal, solarthermal, tidal. no ongoing fuel costs= great for everyone.