<11{7[1(01)]}> Detective: The robbery at the mall was carried out by a mall employee acting alone roughly one hour after the mall closed last Saturday night. The only employees present at the mall at the time of the robbery were security guards Evans and Clark. Since the mall’s surveillance system was disabled by the thief just before the robbery, the thief must be Evans.
The argument above would be valid if
Please see this definition of "robbery."
http://dictionary.reference.com/browse/robbery
If things are being taken from the mall, it would be described as burglary. If Evans took something from Clark while he was present, it would be robbery.
the following condition is true: Evans is the only security guard who knows how to disable the surveillance system.
we can establish that the only employees present at the mall at the time of the robbery were security guards Evans and Clark. Additionally, we need to determine if the fact that the mall's surveillance system was disabled by the thief just before the robbery is sufficient evidence to conclude that the thief must be Evans.
To determine the validity of the argument, we need to assess the logical connection between the premises and the conclusion.
The premises in the argument are:
1. The robbery at the mall was carried out by a mall employee acting alone roughly one hour after the mall closed last Saturday night.
2. The only employees present at the mall at the time of the robbery were security guards Evans and Clark.
3. The mall's surveillance system was disabled by the thief just before the robbery.
The conclusion is:
The thief must be Evans.
To assess the validity, we need to analyze if the conclusion necessarily follows from the premises.
If we assume that the only employees present at the mall were Evans and Clark, and we know that the robbery was carried out by a mall employee, it would seem reasonable to suspect either Evans or Clark. However, just because the surveillance system was disabled by the thief doesn't necessarily mean that Evans is the thief. It is possible that someone else had the opportunity to disable the system or that it was a coordinated effort involving multiple individuals.
Therefore, the argument is NOT valid based on the given information. Further evidence or reasoning would be needed to definitively conclude that Evans was the thief.