Part I - Evaluate the following arguments by analogy in light of the alternative premises listed below it. For each premise, state whether its addition makes the argument more or less probable (or neither). Then identify the criterion of appraisal that justifies this judgment, from ch. 11.3. Explain your reasoning where your think it needs explaining.

3. For each of the last eight years, you have taken a trip to Alaska in May, and enjoyed yourself on each of those trips. This year you plan to take a ninth trip, fully expecting to enjoy yourself again. 

a. Suppose this time you visited in December, rather than May. 

b. Suppose that on four of the previous trips, you traveled to Alaska by train, and on the other four you traveled by plane. On this trip, you attend to travel by automobile. 

c. Suppose that all eight of your previous trips began on a Tuesday or Wednesday, and this trip will begin on a Thursday. 

d. Suppose you instead expect to have the best time of your life on this trip.

e. Suppose you had taken all previous trips with your family, but this time you were traveling alone. 

Part III. In the below paragraph, be sure to answer:

-what data are to be explained?

-what hypotheses are proposed to explain them?

-evaluate the hypotheses as best you can in terms of the criteria presented on pp. 522-525 (Evaluating Scientific Explanations: Compatibility with previously well-established hypotheses, Predictive power, Simplicity) (15 pts)

Boy babies tend to be about 100 grams heavier on average than girl babies, but it has never been explained, until recently, what that is so. Investigators were unsure whether the increased weight was to be explained by the fact that mothers of boys took in more energy, or because (when the fetus was male) those mothers used the energy taken in more efficiently.

Dr. Rulla M. Tamimi, of the Harvard School of Public Health, sought to resolve this uncertainty by measuring the intake of calories. During the second trimester of their pregnancy, 244 women in Boston were asked to record their dietary intake in full detail. The data collected were later correlated with the resultant births. Women carrying boys, Dr. Tamimi found, took in (as carbohydrates, fats, or proteins) about 10 percent more calories than women carrying girls. It is intake, and not efficiency of use, that makes the difference.

But what accounts for that difference of intake? Dr. Tamimi speculated that it may be triggered by some signal from the testosterone given off by the male fetuses.