I believe that the tarot works because it reflects the energies at work in a person's life. Think of a prism that will separate pure light into the colors of the spectrum; the tarot will do the same things for the forces at work in your life. It brings issues into a clearer focus, even - and maybe especially - the issues of which you are not readily aware but which you have registered on a subconscious level. When people come to me for readings, I know they have the answers within themselves and my only task is to find them.
It stands to reason that the more distant in time, the hazier events become, so I usually caution my clients that their reading can be expected to pan out over the next three months. Anything after that is speculation on my part, and probably premature on theirs.
One further note: I have discovered that when a client comes to me for help in making a decision, one of two things happen. Either the cards say, Duh, you already know the answer, or they will only go so far and then draw a blank. If a client has REALLY not made a decision on a crucial issue (like making a marriage proposal, accepting a job in another city, anything life-changing like that), I do not believe the cards can "tell" you what to do. They can only point the way. But I've often experienced them refusing to predict beyond a certain point because a decision has not been made. I think more than anything the tarot encourages you to think CLEARLY FOR YOURSELF and make informed decisions.
I look forward to hearing all your thoughts on this as well!
I agree with Waterqueene for the most part.
I see Tarot working as it does because the cards represent & reflect energy patterns on different levels simultaneously; as we exist on different levels simultaneously. A throw isolates the prevailing energies & produces an overview of what is occurring/not occurring, thus permitting an examination or a means to analyse portents. Like a photograph depicts a specific moment, so will the cards; however, while the photograph is a frozen moment in time, the cards are not bound by such a restriction. They are fluid, subject to change in accordance with an individual's choices or decisions; subconscious workings. They can reveal any of a number of possible "futures", depending on the cumulative effect of all that has occurred up to the time of the throw.