Critical Thinking: An Introduction to Analytical Reading and Reasoning

Last updated Nov 18, 2022

• Source book

Book by Larry Wright

A secondary point may be:

If you’re unsure whether a subordination of type MP because SP is [e] or [s], ask the following question:

Do we know about the MP directly, through observation or simple report of it, or only indirectly through knowing the SP?

• If we know of it directly, then it’s [e]
• If we know of it indirectly, then it’s [s]

• Sometimes only inference ([s] or [r_i]) will make sense.
• When both explanation and inference make sense, indirectness will tell us whether inference is going.

To distinguish between [s] and [q] we must pay special attention to indirectness: whether the author is using the SP as an indicator of something further or just giving us a particular way or sense in which the MP description fits.

As a rule, if there is no indirectness, a “because” that can be paraphrased “in that” will be [q].

• [s_] Explains why we should think the MP is true (how can we tell it happened, if it is an event).
• [e_] Explains why the MP happened, what brought it about.
• [r_e] Explains what effect the MP had, waht it caused.

• A -[e_c]-> B (A was caused by B) B -[r_e]-> A (B causes A)
• A -[s]-> B (A is supported by B) B -[r_i]-> A (B supports A)
• A -[e_m]-> B (A is motivated by B) A -[e_c]-> B (A is caused by B) B -[r_e]-> A (B resulted in A)

Sometimes an SP can have more than one relationship to the MP. The most important of these is when the SP is both explanatory and inferential.

When you have a possible cause, but you’re not 100% sure about it.

• MP: Excessive exposure to the sun causes skin cancer.
  • [e_c]/[s] SP: Ultraviolet radiation genetically alters skin cells.
    • [ s ] SP: (Results of physiological study)

It can also be reversed like shown in reversing connections.

• MP: Ultraviolet radiation genetically alters skin cells.
  • [r_e]/[r_i] SP: Excessive exposure to the sun causes skin cancer.
    • [ s ] SP: (Results of physiological study)

A very common source of [r_e]/[r_i] is prediction.

Example: Consumer confidence is back, so the economy will recover. Here consumer confidence implies the economy will recover, but that’s the case mostly because it will cause it. So we write:

• MP: Consumer confidence is back
  • [r_e]/[r_i] SP: The economy will recover.

Explanations double not only as support, but also implications. We infer explanations from the things they explain.

• Driving along, the car starts to sputter and die; we may infer we are out of gas, because it explains the sputtering and dying.
• The house shakes violently, and we infer there’s been an earthquake nearby, because it explains the house shaking.

When something is both evidence and effect of something.

Example

• MP: A nearby star blew up 35,000 years ago.
  • [s]/[r_e] SP: Unusual levels of beryllium-10 have been found at the 2000-foot level in the Greenald icecap.

Schematizing an argument from a paraphrase will always have two stages:

1. Schematize the reasoning labeled with [s] or [r_i] in the paraphrase.
2. Look for omitted detail that makes a difference to the argument.

a. i. The dynamite exploded, so the shack must’ve gotten too hot in the sun. [e_c]/[r_i] ii. Tony must’ve lost his job, because he had to sell his house. iii. The plane crashed, so it must have been out of fuel.

b.

• S_1: An Amtrak train derailed at a switch
• S_2: Some bolt cutters and shavings were found nearby
• S_3: The sliding switch lock itself is missing
• ……………………………………..
• Therefore, the switch had been tampered with.

c.

• MP: Pima Indians have a special form of LDL.

  • [s_] It transfers LDL to HDL instead of sticking to artery walls.
  • [r_i][r_e][s] This explains low rates of heart disease.
    • [q_] Despite having high rates of diabetes and obesity.

• Schematization

  • S_1: Pima Indians have low rates of heart disease despite high rates of diabetes and obesity.
  • S_2: Results of physiological research
  • …
  • C: The Pimas have unusual LDL

# A Shortcut: Schematizing Directly from a Passage

To extract reasoning from a passage, do 2 things:

1. Recognize that some reasoning (inference, argument) is going on.
2. See what supports what.

We normally do this at the same time, but we need to keep these activities separate. This is because words that signal reasoning can also signal other things, so we must learn to recognize features that signal reasoning.

Reasoning clues have 3 basic kinds and usually work in pairs.

1. General commonsense indicators
   • These are investigation and controversy.
     • General indicators of investigation: “evidence”, “clue,” “discover,’ and (of course) “investigators.” ^9f6e27
     • General indicators of controversy: “should,” “ought,” “right,” and “wrong.”
2. Indirectness flags ^indirectness-flags
   • They distinguish inference from other subordination.
     • Examples: “must,” “may,” “probably,” “likely,” “apparently,” and “seems.”
3. [r_i] and [s] indicators (“because”, “so”)
   • Like “because,” “so,” and “which implies”
   • Often paired with indirectness flags
     • Probably ABC, so XYZ
   • Often paired with general indicators of investigation.
     • ABC ought to have been the perpetrator, because XYZ.

They point back towards support and forward toward a conclusion.

The oncoming cars are all using their windshield wipers, so we must be driving into rain.

Apparently, may, must. They are conclusion flags.

They say that what is coming up is support in the argument.

We must be driving into rain (conclusion), because the oncoming cars are all using their windshield wipers (support).