Sometimes the leading context determines it. My favorite example is unionized. Chemists and labor leaders see this word quite differently. There is a rumor that managers in large chemical companies use this word as a litmus test when making hiring decisions. These words are politically significant.
Many conservatives tout phonics as the best and only way to teach children how to read.
In a Popperian sense, heteronyms disprove their hypothesis. Context does matter. Other Responders Responses have also been received from R. Bishop, M. Chartier, X. Chen, D. Church, E. Collins, S. Feldman, S. Goldwasser, T. Harriman, D. Harris, J. Kirschner, T. Kraft, G. Landis, M. Lindenberg, B. McCue, D. McMahon, J. Nohrden, D. Pastorello, D. Plass, James R., M. Robbin, K. Rosato, J. Rudy, G. Sahagen, R. Salomon, S. Sperry, R. Spinner, L. Stabile, D. Stork, D. Teare, R. Turkel, W. Verrochi, A. Wasserman, T. Yap, and K. Zeger.