Why did Mr. Tulliver wish to give his son a good education?

Mr. Tulliver wants his son, Tom, to have a good education for several reasons. First, he wants to ensure a financially secure future for Tom. Mr. Tulliver tells Mrs. Tulliver that he wants to send Tom to a good school at Midsummer. He means for Tom to have a better education than he himself received at his age.
Additionally, Mr. Tulliver wants Tom to have a good education so that the latter can help him defend against the lawsuits that constantly beset his business. Mr. Tulliver doesn't really want Tom to become the kind of lawyer he despises, however. To Mr. Tulliver, most lawyers are duplicitous in nature. Instead, he wants Tom to know how to speak the language of the courtroom and be able to use those skills against the prosecuting attorneys.
Mr. Tulliver also wants Tom to become a scholar of sorts and to acquire some business skills.
Finally, Mr. Tulliver doesn't want Tom to become a miller and farmer. The truth is that Mr. Tulliver doesn't want Tom to take over the family business while he is still alive.