Self-study
Explanation must be distinguished from justification. █████ █████ ██████ ███████████ ███ ██ ████████████ ████ ███ ████ ██████████ █████████ ██ █████ ██ ████████ ██ ████ ██ ████████ ███████████ ██ ███ ██████ ██ ████ ███████ ██ ██████ ██ █████████ ████ ████ ███ ██████ ██████████ ███ ██████ ███ ██████████ ███████ ███ ███ ███████ █████████ ██ ████ ██████████████ ████ ████ █████ ██ █ █████████████ ███ ██ ███████ ████ █████████████ █████ █████ ██ ████ ██ ███ ████████████ ███ ███████ ██████████ ████████ ██ ████ ████ ██ ██████ █████ ██████████████ ████ ███ ███ ███████ ███ ███ ███████ █████ ██ █████████ ████ ██ ███ ███████████ ██ █████████
Causes vs. Reasons
The stimulus tells us about two terms. Explanation means the causes of an action (what actually made it happen). Justification means the reasons someone has for the action (what would make the action warranted). These two don't always overlap.
To make it concrete, picture someone donating $100 to charity. The explanation (causes) might involve all sorts of things: their mood, social pressure, an article they read, whatever was actually firing in their head when they hit "donate." The justification (reasons) would be claims like "charity helps people" and "I had money to spare." The stimulus's point is that those reasons might not actually be part of what caused the donation. Maybe the donor was really trying to impress someone, and the talk about charity is just the story they tell themselves afterward.
The final sentence gives a principle for when an action counts as rational: only if the reasons are an essential part of the causes. Back to the donor: the donation is rational only if "charity helps people" and "I had money to spare" actually played a role in causing it, not just in narrating it after the fact.
Anticipation
Boiling the principle down: rational → reasons are an essential part of the causes. If reasons are essential to the causal story, they're at least part of the causes. So any rational action has reasons among its causes.
The contrapositive: if reasons are never causes, then no action is ever rational. So the existence of even one rational action requires that reasons sometimes be causes. That's the inference we can pull out before looking at the answers.
24.
If the statements in the ███████ ███ ████████ █████ ███ ██ ███ █████████ ███ ██ ████████ █████████ ████ █████
a
When a human ██████ ██ ██████████ ████ ██████ ███ ██ ████████████
Even justified actions have explanations. The stimulus says EVERY human action potentially has an explanation, given sufficient knowledge of the causes. Justification doesn't make an action's causes vanish; the donor in the example still has causes for the donation, whether or not those causes match up with the reasons.
b
If there are ███ ███████ █████ ███ ██████ ██ ██ ███████ ████ ████ ██████ ██ █████████
This reverses the conditional. The stimulus says rational → reasons are an essential part of the causes. (B) says reasons among the causes → rational. Even if reasons happen to appear in the causal mix, they might not be ESSENTIAL (the stimulus is specific about that word). The donor in the example might have been partly motivated by the reasons and mostly motivated by impressing someone; reasons would be among the causes without being essential, and the action wouldn't count as rational.
c
Some psychologists believe ████ ███ █████████████ ███ ██ ██████ █████ █████ ██ █████████ ████ ██ ███ ████████████
Too strong. The stimulus says many psychologists believe justification "often" forms no part of the explanation. "Often not" isn't "never." The psychologists' view leaves room for justification sometimes being part of the explanation. (C) takes "often" and ratchets it up to "never," which the stimulus doesn't support.
d
There are actions █████ ██████ ██████ ██ ███████████
The stimulus says that with sufficient knowledge it would be possible to give an accurate description of an action's causes. So in principle every action's causes can be discovered. We have no reason to think some actions have causes that can't be discovered.
e
If any human ███████ ███ █████████ ████ ███████ ████ █████████ ██ ██████ ██ ████████
This follows from the principle. If any action is rational, the principle requires the reasons for that action to be an essential part of its causes. So for that action, reasons are among the causes. If reasons are never causes anywhere, no action could be rational; so as soon as one rational action exists, reasons must sometimes be causes. That's exactly what (E) claims.