The popular view of Tarot cards is that they "tell the future". That is the meaning of the popular synonym for divination, "fortune-telling". Any sort of question may be asked of the Tarot cards, which does not exclude telling the future. But that is not the only end to which the cards may be put.
When telling the future, the questions of predestination and psychic powers inevitably arise. If we can accurately read the future, then the future must already exist in some sense, and we must have some way of viewing it.
On the question of predestination, science and philosophy are inconclusive. Modern physics is clear that the world is not deterministic; there are many experiments with physics on a small scale that show nature to be probabilistic. Many things happen on the sub-atomic scale without any real reason, simply because it was more or less likely that they would happen and they wound up happening or not. This would seem to fly in the face of predestination; the future state of the universe depends on truly random and unpredictable events.
But these events may be truly random yet, in a sense, already have happened. Time may be viewed as a fourth dimension like our usual three spatial dimensions. If so, then one may take a static view of the universe's history, in which the whole of time is a static construct when viewed from without, that is, from a five-dimensional perspective. The exact nature of the "arrow of time" has yet to be clearly determined, and it is impossible to say now whether a higher-dimensional traveller would see the past as still with us and the future as already laid out.
The question of psychic powers is even more difficult. No such powers have ever been shown to exist in any replicable experiment; at best, such experiments barely squeak in under the margin of significance, and then only after averaging thousands of trials which are not individually significant.
Yet many people believe in them regardless, and these people erect theories to explain them. One of the more popular theoretical ideas of psychic powers is that the psyche somehow exists in a higher dimension. From a higher-dimensional viewpoint it might be possible to look out over the four-dimensional history of the world and see what is to come.
This is written in 1990 in San Francisco, and it seems rather telling to this writer that of the great events which have taken place recently -- the destruction of the Berlin Wall, the independence of Eastern Europe, the San Francisco earthquake -- none were foretold by psychics. One would think such momentous happenings would fairly blaze forth before a psychic eye, yet they didn't.
It is probably best to use a weaker form of the precognition idea, which does not involve a predestined future or psychic powers. Instead, the unconscious mind is viewed as having the power to perceive more or less where some events are heading, and to present its views on the subject -- which may be right or wrong -- through a Tarot reading. Of course, the conscious mind can also make some predictions based on its knowledge. The idea is that the unconscious mind is attentive to different factors and will make predictions the conscious mind could not.
Another "weak" form of precognition involves synchronicity. Events and Tarot readings are "riding the same waves", so one can cast light on the other.
Finally, it is best to take all answers about the future with a grain of salt. It is also wise to phrase questions in such a way that they ask for perspectives on what is happening and what has happened, and for guidance, rather than for outright predictions of the future.
Books You Might Enjoy:
Tuesday Lobsang Rampa - The Saffron Robe
Eliphas Levi - The Key Of The Mysteries
Ea Wallis Budge - Egyptian Ideas Of The Future Life
Tuesday Lobsang Rampa - The Third Eye
Melita Denning - The Aurum Solis