Logic and
Critical Thinking

Philosophy 4

Gale Justin

Chapter 5: Diagnostic Arguments

Focuses on arguments in which we infer an explanation of trace data.

For example in 4.21 where we discover deftly skinned animal carcasses, the carcasses are trace data.

Trace Data (TD): are parts, features, visible effects of an event. They are what is being explained by the inferred explanation, which is the conclusion of the diagnostic argument.

For example in 4.21 where we discover deftly skinned animal carcasses, the carcasses are trace data.

In this case, the inferred explanation is that the carcasses are probably carcasses of coyotes.

Trace Data:

• T.D. is always specific; and, it provides specific support for a conclusion.
• Central T.D. is data that all of the rival conclusions must explain.
• Peripheral T.D. is data explained by one or more of the rival conclusions.
• The conclusion of the diagnostic argument is the best explanation of the TD. It is itself one of the rivals.

Exercise 5.4 (p. 207):

Rivals are competing answers to the IQ. The strongest rival will be the conclusion of the diagnostic argument. What is the IQ in the following cases:

What rival best explains, and in consequence is the conclusion of the diagnostic argument that explains the trace date in the:

Hurtle:

Non-Trace Data:

• Helps in the explanation of the TD but is not itself something that needs to be explained.
• The facts that the Soviet satellite’s orbit would take it over Canada, that it had been reported missing and that it had a nuclear reactor on board are specific non-trace data.
• The fact that depression causes suicide is general NTD and helps in explaining the disappearance of Busby.

Recall the Busby Case:

Investigators found the blood-spattered fishing boat of Travis Busby who was reported missing. A gun which had been fired once was discovered on board. Travis who had been depressed about financial problems rented a fishing boat with a full fuel tank. The boat was found with an empty fuel tank and its navigation lights on. A billfold, a dinghy and uninflated raft were also on board.

Trace Data in the Busby case:

A. Busby is missing.

B. Blood spattering on the boat.

B. Gun, fired only once,is on board the boat.

C. Fuel tank is empty.

D. Navigation lights were on.

E. A wallet, a dinghy and an uninflated raft are on board the boat.

Diagnostic Argumentt for Busby case:

S₁Busby has disappeared.

S₂ A once-fired gun, a billfold, dinghy, uninflated raft were found on board.

S₃ The fuel tank was empty, the navigation lights were on and there was blood spattering on the boat.

S₄ Busby had been depressed over money matters.

_________________________________

C₅: Busby probably committed suicide.

See definitions of Sound Argument and Strong Argument on page 215.

5.16:

The campus is nearly deserted as you hurry in from the parking lot on your way to class. This is unusual. Normally there’s a crowd of students going and coming. You look at your watch. It says 10.05, five minutes before class time, but it’s been running slow lately and you don’t remember setting it. You infer that you are late for class.

After Argument Terms quiz, do now:

Homework: