"Never" using condoms is ~93% effective, "always" using condoms is ~99% effective, therefore "always" is 85% MORE effective than "never."The major and minor premises of the above-stated syllogism are both false.
Major Premise: Never using condoms is never effective, as can be demonstrated by a simple syllogism:
Every effect has a cause;To say that "never" using condoms is 93% effective is like saying that condoms are 93% effective when not used, which is absurd. As the poster in #6 above correctly pointed out, condoms are 0% effective when not used.
Inaction is not a cause;
Therefore, inaction has no effect.
Minor Premise: The effectiveness of a prophylactic is calculated by (a) subtracting the total number of unfavorable events that occur in the group using the prophylactic from the total number of unfavorable events that occur in the control group (i.e., the group not using the prophylactic, and (b) dividing the difference by the total number of unfavorable events that occur in the control group. For example, if we wanted to know how effective seat belts were in preventing traffic fatalities and we knew that 7 of 100 motorists who never wore seatbelts were killed in traffic accidents but only 1 of 100 motorists who always wore seatbelts were killed, we would subtract 1 from 7 and divide the difference by 7, giving us an effective rate of .85, or 85%.
The data in our example do not support the onclusion that seatbelts are 99% effective. To determine the effectiveness, we have to compare the results of the test group to the results of the control group. Comparing the actual number of traffic deaths in the test group (1) with the total number of motorists in the test group (100) doesn't tell us how effective seatbelts are, only the chances of surviving a traffic accident while wearing a seatbelt -- that is, 99 out of 100 times, or 99%.
The data support Bozell's conclusion that condoms fail to prevent HIV transmission 15% of the time . Condoms are 85% effective against HIV transmission, not 99%.