In "The Galileo Seven"
Then I noticed it came up again in Voyager episode "Collective"SCOTT: Pressure's dropping. We're losing everything.
SPOCK: What happened?
SCOTT: One of the lines gave. The strain of coming through the atmosphere and the added load when we tried to bypass. Yes, that's done it. We have no fuel.
SPOCK: That would seem to solve the problem of who to leave behind. Consider the alternatives, Mister Scott.
SCOTT: We have no fuel! What alternatives?
SPOCK: Mister Scott, there are always alternatives.
SCOTT: Tapping our boosters ended our last chance for a soft landing.
BOMA: You mean a burn-up?
SPOCK: It is the usual end of a decaying orbit.
MEARS: I don't want to die up here.
SPOCK: Infinitely preferable to the kind of death we'd be granted on the planet's surface, I should think.
BOMA: I admire your ability to make so measured a choice.
SCOTT: Mister Spock, you said a while ago that there were always alternatives.
SPOCK: Did l? I may have been mistaken.
MCCOY: Well, at least I lived long enough to hear that. Is there anything we can do?
SPOCK: The Enterprise is surely on course for Makus Three by now. I for one do not believe in angels.
Tuvok said there were no alternatives, Janeway corrected him and said there were always alternatives and Tuvok did not argue, though he did not explicitly agree either.TORRES: That'll buy us another minute at most.
TUVOK: Captain, I have found a fluctuation in their shield grid near a plasma duct. It's too intermittent to beam out the hostages, but we could use it to deploy the pathogen. Captain.
JANEWAY: Not yet.
TUVOK: There is no alternative.
JANEWAY: There's always an alternative. We just need to find it. Their tractor beam draws power from the same grid as their shield matrix. If we use the deflector to send a feedback pulse along the beam, it could disrupt their shields. Do it.
TOS "City on the Edge of Forever"
Spock said there was no alternatives here but I think he meant no "acceptable" alternativesKIRK: Make sure we arrive before McCoy got there. It's vital we stop him before he does whatever it was that changed all history. Guardian, if we are successful
GUARDIAN: Then you will be returned. It will be as though none of you had gone.
UHURA: Captain, it seems impossible. Even if you were able to find the right date
SCOTT: Then even finding McCoy would be a miracle.
SPOCK: There is no alternative.
KIRK: Scotty, when you think you've waited long enough. Each of you will have to try it. Even if you fail, at least you'll be alive in some past world somewhere.
SPOCK: Seconds now, sir. Stand by.
TOS "Doomsday Machine"
Spock says no alternatives here though he's speaking in the context of starfleet regulations.DECKER: Mister Spock, that will be all. You have been relieved of command. Don't force me to relieve you of duty as well.
MCCOY: You can't let him do this, Spock.
DECKER: Doctor, you are out of line.
MCCOY: So are you, sir. Well, Spock?
SPOCK: Unfortunately, Starfleet Order 104, Section B, leaves me no alternative. Paragraph 1A clearly states
MCCOY: To blazes with regulations! You can't let him take command when you know he's wrong!
SPOCK: If you can certify Commodore Decker medically or psychologically unfit for command, I can relieve him under Section C.
MCCOY: I'll certify that right now.
SPOCK: You'll also be asked to produce your medical records to prove it.
MCCOY: Now, you know I haven't had time to run an examination on him.
SPOCK: Then your statement would not be considered valid.
TOS "The Devil In The Dark"
Spock says he sees no alternatives which I see this phrase used a lot. Though not being able to see or think of alternatives is not proof that alternatives do not exist.KIRK: Mister Spock, our mission is to protect this colony, to get the pergium moving again. This is not a zoological expedition. Maintain a constant reading on the creature. If we have to, we'll use phasers to cut our own tunnels. We'll try to surround it. I'm sorry, Mister Spock, but I'm afraid the creature must die.
SPOCK: I see no alternative myself, Captain. It merely seems a pity. The search team is gathering in the main tunnel.