Air carrier Captain reported refusing an aircraft for TCAS being on MEL. Captain also expressed concern about operational pressures being applied to decision as PIC.

Narrative

To start; I think we can all agree that there is a difference between what is legal and what is safe. After I woke up on the morning of X/XX; I immediately checked on the maintenance history and MEL's for the plane that I had three legs scheduled in. I noticed the TCAS was MEL'd inoperative. Following the events at ZZZ; I really did not want to fly any aircraft without an operating TCAS. I completely realize that the TCAS probably did not make a difference in that particular instance; but it is an additional layer of safety that I feel should not be compromised especially when we are flying passengers. I tried my best to give ZZZ control as much notice as possible (hours before scheduled departure time); but when I called the ZZZ controller; I was immediately questioned and met with so much pushback on my refusal to fly that airplane. I was then called by the Flight Ops Manager who also pushed me into a corner saying that if I refused to fly that airplane then I would have to be the one to take a mark on my reliability and call out of work. I was told 'we are trying to run an airline' and in my head; all I could think is; 'but aren't we trying to run a SAFE airline?'. After talking to the ZZZ controller; the ZZZ control supervisor; and the Flight Ops Manager; I felt that my PIC discretion was completely disrespected. I understand needing to get an airplane moved to a maintenance base to get the TCAS fixed may be necessary; but this airplane flew multiple legs without an operating TCAS; not to mention some of the other MEL's on this plane that already made flying it way more stressful than normal. I do not feel it is safe or wise to be flying airplanes around without TCAS. This particular airplane touched a maintenance base multiple times before it came to me and could have been fixed. I was also told the pilot bringing it to me in ZZZ1 from ZZZ2 had 'requested to keep the airplane and not switch out'. When I received the airplane from him in ZZZ1; he said no one ever called him and he had never requested to keep this plane. He said I was completely lied to about that. I was very disappointed about how I was treated when I care primarily about upholding safety and the safety of my passengers. I am the PIC and I felt like that stood for nothing.Cause: A lot of the airline's aircraft have multiple maintenance issues as they continue to grow older and older. The TCAS being MEL'd inoperative makes it legal; sure; but it does not make it safe. That system has saved me before and we shouldn't be risking hundreds of lives by flying airplanes without TCAS. Suggestions: Not compromising safety for the operation of an airline should always be a focus. Fixing the airplanes when they arrive at maintenance bases so that they don't continue to fly throughout the system without operable TCAS should be a priority. This should not be a question. Also; not disregarding a PIC's concern for safety when dealing with a refusal to fly a particular airplane would avoid this type of recurrence.