Berkeley's view of time as the succession of one's ideas is indeed very puzzling. Berkeley seems committed to the claim that there is no common time; there is just time for you and time for me, etc. God does give each of us successions of ideas that can be roughly coordinated, just as you say. For instance, we are able to agree on when the second hand of a clock is successively pointing at different numbers. However, this does not mean that our ideas succeed each other at the same basic rate. My ideas may be flowing much slower than yours, so that watching the second hand is boring for you but not for me. It happens slowly for you, but not for me. A consequence of this subjective account of time is that there is no time for me that I am not having an idea. That does not mean that I am unconscious of some ideas when I am in a deep sleep. It means that there is no time for me when I am in a deep sleep, so no time at which I am lacking a conscious idea. This seems odd, given that my wife might watch me sleep...

Trying to convince people (and oneself) and alleviate their confusion (and one's own) and learning from the responses is our best way to approach the truth about matters for which observation and calculation are little help in resolving controversies. It is an imperfect way to the goal of truth, granted. It is hard to see why intersubjective agreement should even be connected to truth, granted. But this approach at least helps weed out inconsistency, irrelevance, prejudice, and partisanship, when it works. It helps direct people towards open-mindedness rather than arrogance, persuasion rather than violence. And it helps temper our tendencies toward willfulness and illusion.

My opinion is personal, but based on experience with trying to argue and publish arguments, with trying to teach students to argue and to write out arguments, and with conferring with other philosophers. Thinking and articulating go hand in hand. One must think very hard about philosophical questions. However, one does not understand what one cannot articulate. Initially, thinking will consist of wonder, inspiration, and brain-storming. But to arrive at a result of any value, the thinking must transition into attempts to articulate one's thinking to others. Then these attempts must be put to the test by trying to convince others, and then taking into account their incomprehensions and objections. That requires more thinking. This process of trying our thoughts out on others and learning from their responses is our only way to avoid philosophical insanity and illusion. Philosophical thinking is a corporate enterprise, not individual, and articulation is what binds it together.

Nice conundrum. Here is a stab at it. If, in the example, time travel is traveling back one year of time in an instant of another time dimension--call it metatime--then Einstein has not been contradicted. He is silent about how much space can be covered in an instant of metatime. So time travel, conceived this way could be possible even given our actual laws of nature, if there is metatime. If, however, there is no metatime, then traveling back in time would be a case in which what would normally be a later stage of one's life occurs before what would normally be an earlier stage (see David Lewis, "The Paradoxes of Time Travel"). For this to be possible, the laws of nature would already have to be different than ours in such a way as to also allow that what would normally be the very next stage in ones' life occur far away from the current stage. If it is conceivable that the laws of nature be different than what they actually are then time travel would be conceptually possible. And this is the sense of ...