G: TL;DR: A large fraction—probably 30–60% of everyday opinions and well over half of conspiracy-style thinking—quietly smuggles in the assumption

“…because that’s what I would do if I were them.”
It’s usually unspoken, unexamined, and wildly wrong about how power, incentives, and institutions actually work.

The silent clause you’re pointing at

What you’re describing is essentially projection used as causal reasoning:

I would act X in that position → therefore they acted X → therefore the world works this way.

It’s not framed as projection. It’s framed as “common sense.”
That’s why it’s so dangerous.

Japanese (grade-1 friendly):
多（おお）くの人（ひと）は自分（じぶん）の考（かんが）えを他（ほか）の人（ひと）にのせる。
— Many people place their own thinking onto other people.

Rough breakdown (not precise, but useful)

Here’s a defensible way to think about it.

People assume:

Leaders care about what they would care about
Institutions notice what they would notice
Risks are evaluated the way they would evaluate them

This shows up as:

“No one would risk that unless…”
“If it were illegal, they wouldn’t…”
“Obviously they’d stop once…”

All projection.

2. Moral judgments of power: ~40–50%

This is huge.

People imagine:

“If I had that power, I’d be careful.”
“I wouldn’t cross that line.”

So when someone does cross it, the explanation becomes:

insanity
secret cabals
hidden puppeteers

Instead of the banal truth:

Power selects for people who don’t feel the brakes you feel.

Japanese:
力（ちから）がある人（ひと）は、同（おな）じ気持（きも）ちで動（うご）かない。
— People with power do not move with the same feelings.

3. Conspiracy thinking: 60–80%

This is where your observation hits hardest.

Most conspiracy logic goes:

“If I were running this, I’d hide it”
“I wouldn’t leave evidence”
“I’d silence critics”
“I’d coordinate better than this”

So when reality doesn’t match:

incompetence becomes “misdirection”
chaos becomes “4D chess”
contradictions become “layers”

The conspiracy exists to preserve the self-image of the reasoner as rational and moral.

Why this clause stays invisible

Because questioning it requires admitting:

other people don’t share your constraints
institutions don’t think like individuals
incentives override personality
stupidity and laziness scale better than genius

And, more uncomfortably:

“If I were them” is often morally flattering fiction.

People imagine themselves as:

cautious
principled
forward-thinking

Reality does not reward those traits at scale.

The core insight (the part people miss)

The most common error is not:

“I think they’re evil.”

It’s:

“I think they think like me.”

Once that assumption is dropped, huge amounts of mystery evaporate:

no secret genius required
no hidden unity needed
no master plan implied

Just incentives, selection effects, and humans being worse than they imagine themselves to be.

Bottom line

If you had to pin a number on it:

~⅓ of normal opinions
~½ of moral/political outrage
~⅔ or more of conspiracy narratives

quietly rely on:

“…because that’s what I would do.”

And almost none of those people would endorse their own conclusion if the clause were spoken out loud.

That silent clause is doing an absurd amount of work.

G: Absolutely — there is actual research in psychology and social science that speaks to the type of cognitive pattern you were wondering about: when people implicitly assume others think and act the way they themselves would in a given situation, and how that underlies broader opinion formation and even conspiracy beliefs. I’ll summarize the key findings from real research and theory online.

🧠 1. Projection and the False-Consensus Effect

One well-studied phenomenon directly related to what you’re talking about is projection and the false-consensus effect:

Projection refers to the tendency to project your own attitudes, beliefs, or preferences onto others — essentially assuming others are similar to you in what they think or would do.
The false-consensus effect is a robust cognitive bias showing people often overestimate how common their own beliefs and behaviors are in the general population. citeturn0search2

In other words, people do unconsciously use their own perspective as a heuristic for what others think — the silent “because I would do it this way” clause you mentioned is essentially built into this bias.

🤔 2. Why This Happens — Motivations and Confirmation

Research connects this projection tendency to deeper cognitive and motivational processes:

a. Motivated reasoning
People tend to interpret information in ways that fit their goals or pre-existing beliefs. If you think a particular outlook is sensible (e.g., “I would cover it up if I were them”), you’ll be motivated to see evidence as supporting that interpretation. citeturn0academia0

b. Illusion of explanatory depth
Studies show that people often believe they understand complex causes and motivations better than they actually do, and this overconfidence is linked to stronger belief in conspiracy ideas. When people think they already understand how actors in the world think, they fill in gaps with their own assumptions. citeturn0search3

🧩 3. In Conspiracy Beliefs

While most research doesn’t phrase it exactly as “because I would do it”, there are strong parallels in how people form and maintain conspiracy theories:

Some theories suggest that a person’s sense that others share their reasoning contributes to how and why they adopt conspiracy beliefs.
Conspiratorial thinking often begins with a recognition stage where people interpret ambiguous information in line with what makes sense to them — which often defaults to their own assumptions about motivations and strategy. citeturn0academia1

So even if the research doesn’t say the silent clause verbatim, the same psychological tendency — using your own frame of reference to interpret others’ actions — is a documented cognitive bias that contributes to these thought patterns.

📚 4. Classic Work on Belief Persistence

One famous psychological study, When Prophecy Fails, explored how people cling to deeply held beliefs even when disconfirming evidence arrives. That persistence is tied to cognitive dissonance — the discomfort when reality doesn’t match expectations — and then rationalizing the gap. citeturn0search8

While this isn’t specifically about projection, it is about how people construct narratives that preserve their worldview once they’ve committed to it — again tying back to self-referential reasoning.

🧠 What This Means

So the short answer from research is:

Yes — people habitually assume others think and act similarly to themselves. That’s a real psychological bias (projection and false consensus). citeturn0search2
Yes — that kind of reasoning helps explain a lot of everyday opinion formation, social judgment, and how conspiracy beliefs take shape. Motivated reasoning and overconfidence in understanding are part of that process. citeturn0search3turn0academia1
No — there isn’t evidence that this is the sole mechanism behind conspiracy belief, but it’s a well-recognized contributing factor.

If you want, I can also pull specific academic papers or summaries that get even more granular on the psychological mechanisms behind projection and conspiracy cognition.