but surely we can at least all agree that Franklin is a pretty ethical and moral guy
As you said... argument by authority... but every authority errs, and every rule has exceptions. In this case, I consider his assistance unethical -- and think he should have refused.
Would you people honestly be able to "trust" telepaths?
By default I don't trust anyone. I would strive *not* to trust... either telepaths or mundanes beyond the level of time/cooperation an individual has invested into gaining my trust.
However, should an individual gain my trust -- via repeated mutually beneficial cooperation, despite opportunity to cheat -- I would trust that individual, to level which I consider adequate in light of previous experience. Even if their set of abilities should differ from mine.
To persons whose abilities might be dangerous to me... gaining trust would simply be more difficult, and the calculation of how close to let them at particular points during confidence-building... would be more conservative.
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Telepaths would simply face an additional problem. Aware of them carrying a weapon which they cannot drop... a weapon for altering my perceptions... I might have to approach them armed. With my own weapons.
Trying to imagine myself into the world of B5... how would I ground the hazard of telepathy? Via technology. I might carry around a pocket-sized drone, with ability to monitor my mind against signs of tampering, locate any source of such tampering... and engage such an individual... in exchange of payload.
This would be an individual solution. On civilization level however, far smarter opportunities might become available:
1) Once somebody has telepathy, a civilization might decide to offer opportunity of becoming telepathic... freely to every person, if they only want, and technology permits.
2) Once somebody has telepathy, a civilization might decide to offer opportunity of dropping telepathic ability... freely to every person, if they only want, and technology permits.
3) Once telepathy develops... understanding of biological mind would presumably quickly develop... and soon enough, opportunities might open for notably enhancing biological mind.
People might enhance their mind with technologies which take it beyond reach of telepathy (how about optical quantum computing)...
...or oppositely, while staying within reach of telepathy... adopt cryptographic/steganographic techniques to reduce mind-tampering to simple barbaric attack.
If a telepath could not understand a mind, he/she could only use brute force to try destroying it... but a mind capapble of hiding its real structure would hardly expose its vulnerable points... and might thus withstand telepathic attack sufficiently well for most telepaths to utterly exhaust themselves before causing a mild headache.